Aitken Et Al (2001)

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The Quarterly Journal of

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Re-examination of the

role of within-compound

associations in the

retrospective revaluation of causal judgementsMichael R.F. Aitken

a , Mark J.W. Larkin

a &

Anthony Dickinsona

a University of Cambridge, Cambridge, U.K.

Published online: 22 Oct 2010.

To cite this article: Michael R.F. Aitken , Mark J.W. Larkin & Anthony Dickinson

(2001) Re-examination of the role of within-compound associations in the

retrospective revaluation of causal judgements, The Quarterly Journal of

Experimental Psychology Section B: Comparative and Physiological Psychology,

54:1, 27-51

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THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2001, 54B (1), 27 – 51

Re-examination of the role of within-compound

associations in the retrospective revaluationof causal judgements

Michael R.F. Aitken, Mark J.W. Larkin, and Anthony Dickinson

University of Cambridge, Cam bridge, U.K.

We investigated blocking and ret rospective revaluation of causal judgem ents using a scenario in

which food cues acted as potential causes of an allergic reaction as the outcome. In the block-

ing contingency, the treatment cues were either paired or unpaired with the outcom e prior to a

second stage in which sequential compounds of treatment and target cues were paired with the

outcome. The order of this compound and treatment training was reversed in retrospective

revaluation contingencies. When the interstimulus interval between the treatment and target

cues was un®lled on compound trials (Experiments 1 and 3), both blocking and retrospective

revaluation were observed in that the target cue trained in compound with the paired treatment

cue attracted lower causal ratings than the target cue trained in compound with the unpaired

treatment cue. By contrast, performing a mental arithmetic task using numerals presented

during the interstimulus interval had no effect on the magnitude of blocking but rendered retro-

spective revaluation unreliable (Experiments 2 and 3). These results provide further support for

accounts of revaluation based upon within-compound associations.

Dickinson, Shanks, and Evenden (1984) noted the similarities between the acquisition of

causal judgements and conditioning. When humans learn to judge the ef®cacy of cues in

causing an outcome during training episodes in which the cues are either paired or unpaired

with the outcom e, the cues are functionally equivalent to Pavlovian conditioned stimuli and

the outcome to the unconditioned stimulus. On the basis of this analogy, Dickinson et al.

(1984) suggested that the acquisition of causal judgements is controlled by associative

processes that are similar to those mediating conditioning (e.g., Mackintosh, 1975; Pearce,

1987; Pearce & Hall, 1980; Rescorla & Wagner, 1972; Wagner, 1981) with the judgement

based upon the strength of the association between the cue and outcome. This analysis is

supported by the fact that causal and predictive learning by humans exhibits many of the

phenomena of animal conditioning: Blocking (e.g., Chapman & Robbins, 1990; Dickinson

Requests for reprints should be sent to A. Dickinson, Department of Experimental Psychology, University of

Cambridge, Downing Street, Cambridge, CB2 3EB, U.K. Email: [email protected]

This research was supported by a grant from the Biotechnology and Biological Sciences Research Council of

the United Kingdom a nd was conducted within the MRC Co-operative on Brain, Behaviour, and N europsychiatry.

© 2001 The Experimental Psychology Society

http://www.tandf.co.uk/journals/pp/02724995.htm l DOI:10.1080 /0272499004200002 9


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28 AITKEN, LARKIN, DICKINSON

et al., 1984; Kam in, 1969; Martin & Levey, 1991); overshadowing (Kamin, 1969; Pavlov,

1927; Price & Yates, 1993); the effect of signalling unpaired outcomes (e.g., Rescorla, 1984;

Shanks, 1989); relative validity effects (e.g., Vallée-Tourangeau, Baker, & Mercier, 1994; Van

Hamme, Kao, & Wasserman, 1993; Wagner, Logan, Haberlandt, & Price, 1968); super-

learning (Aitken, Larkin, & Dickinson, 2000; Rescorla, 1971); and conditioned inhibition

and learning under a negative contingency (e.g., Chapman & Robbins, 1990; Rescorla &

Holland, 1977; Williams, 1995).

Recently, however, a class of selective learning effects has been demonstrated in both ani-

mal conditioning (e.g., Miller, Hallam, & Grahame, 1990; Miller & Matute, 1996) and

human causal and predictive learning (Chapman, 1991; Dickinson & Burke, 1996; Shanks,

1985; Wasserm an & Berglan, 1998; Wasserman, Kao, Van Hamme, Katagiri, & Young, 1996;

Williams, Sagness, & McPhee, 1994) that requires retrospective revalua tion of the status of

a cue. In the ®rst stage of a typical retrospective design, illustrated in Table 1, two com-

pound cues, AB and CD, are paired with the outcome before the treatment cues from thesecompounds, A and C, are trained separately in a second stage. The key ®nding is that pre-

senting the treatment cue C without the outcome in Stage 2 (CD1C2 contingency)

enhances the ®nal causal rating of the target cue D relative to that of the target cue B whose

treatment cue A is paired w ith the outcome during the second stage (AB1A1 contingency).

Retrospect ive revaluation is problematic for standard associa tive theories because these

theories assume that a cue has zero associability on trials when it is not present and there-

fore preclude changes in its associative strength. And yet this is exactly the effect observed in

retrospective revaluation – -training the treatment cues A and C in Stage 2 leads to the

retrospective revaluation of the relative causal status of the target cues B and D.

To encompass retrospective revaluation within associative theory, Dickinson and Burke

(1996) suggested that within-compound associations are formed between the treatment and

target cues during the ®rst, compound stage of training so that the presentation of the treat-

ment cue alone in the second stage activates a representation of the target cue. Following the

suggestion by Van Hamme and Wasserman (1994 – -see also Markman, 1989; Tassoni, 1995)

TABLE 1

Design of experiments

C ontingencies Stage 1 Stage 2

Retrospective revaluation AB1, CD1 A1, C2

Blocking E1, G2 EF1, G H1

Filler IJ2, K 2 I2, KL2

Note: Compound cues were presented sequentially with

a 2-s ISI. In Experiment 1 a blank white screen was pre-

sented during this interval, whereas in Experiments 2 and

3, numbers were presented for mental addition during the

ISI of some of the compound trials and following cue

presentations on some of the treatment cue trials. See text

for m ore details.

Treatment cues: A, C, E, G.

Target cues: B, D, F, H.

Filler cues: I, J, K, L.

1: outcome; 2: no outcome.


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WITHIN-COMPOUND ASSOCIATIONS 29

that absent cues have a negative associability, Dickinson and Burke (1996) argued that the

change in associative strength generated by a learning episode involving a cue representa-

tion, which is activated via a within-compound association, is the opposite of that produced

by a cue presentation. So, just as presenting a cue in the absence of a predicted outcome

reduces its associative strength, activating a representation of the target cue D in the absence

of the outcome during the second stage of the CD1C2 contingency enhances the associa-

tive strength of Cue D. Correspondingly, pairing the activation of the representation of Cue

B with the outcome in the second stage of the AB1A1 contingency should, if anything (see

Larkin, Aitken, & Dickinson, 1998), reduce the associative strength of the target cue B,

given that direct pairings of a cue presentation w ith a less than fully predicted outcome

enhances associative strength.

Dickinson and Burke (1996) investigated the role of within-compound associations in

retrospective revalua tion by manipulating the conditions for the formation of associations

between the treatment and target cues during the ®rst, compound stage of training. On thepremise that the formation of such associations bene®ts from the consistent pairing of a

treatment cue with the same target cue, they varied the consistency of these pairings. A

number of different speci®c cues played the role of the treatment cues A and C and of the

target cues B and D so that, for example, a particular B target cue could be presented in

compound with either the same A treatment cue on each compound trial or a different A

cue on each of these trials. Retrospective revaluation was observed when each treatment cue

was paired with the same target cue across a series of compound training trials in the con-

sistent condition. By contrast, the contingency between the treatment cues and the outcom e

during Stage 2 had no effect on the ratings of the target cues when each treatment cue was

paired with a different target cue on every trial of compound training in the varied condi-

tion. In other words, varying the pairings between the treatment and target cues abolished

retrospective revaluation, a ®nding that accords with the within-compound associative

analysis. Larkin et al. (1998) replicated the effect of the consistency of treatment – target cue

pairings on retrospective revaluation and provided direct evidence from a recognition test

that the consistency manipulation modulated the ability of the treatment cue to retrieve the

target cue.

It must be acknowledged, however, that the abolition of retrospective revaluation in thevaried condition is not an unambiguous prediction of the associative account. Although it is

the case that the varied condition should reduce the strength of the within-compound asso-

ciation between a given target cue and any particular treatment cue, this target cue is also

associated with more treatment cues in the varied than in the consistent condition. Therefore,

any particular target cue can be activated by the presentation of every treatment cue, albeit

via weak within-compound associations, in the varied condition and so has more opportuni-

ties to change its associative strength during the second stage when the treatment cues are

trained by themselves. In the consistent condition, by contrast, a particular target cue is acti-

vated by only the treatment cue with which it was paired, but in this case the within-

compound association, and hence the activation, is strong. Consequently, the prediction that

the varied condition reduces retrospective revaluation relative to the consistent condition is

predicated upon the assumption that any effect of associating a target cue with more than one

treatment cue is outweighed by the reduced strength of the within-compound associations

in the varied condition. The ambiguity of the prediction of associative theory about the


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consistency manipulation encouraged us to seek further, converging evidence on the role of

within-compound associations in retrospective revaluation.

In the present experiments we sought to reduce the formation of within-com pound asso-

ciations by requiring the participants to perform an interfering task during compound train-

ing. The scenario and stimuli were those employed by Larkin et al. (1998) in which each

participant plays the role of an allergist who is required to judge the likelihood that different

foods cause an allergic reaction in a hypothetical patient. Thus, the foods are causal cues, and

the allergic reaction is the outcome. Participants base their judgements on training episodes

in which they are shown images of meals that the hypothetical patient has eaten. Figure 1

illustrates the sequence of events that can occur in compound trials with the treatment and

target cues. Each trial starts with a presentation of a food cue (e.g., ham or chicken), followed

after a short interstimulus interval (ISI) by a second cue (e.g., beans or cheese). On the termina-

tion of the second cue, the participant is prompted to make a response predicting whether or

not the outcom e, an allergic reaction , will occur on that trial. Finally, following the predictiveresponse, the participant is informed about whether or not the outcome occurs.

In the interference condition, three numbers are presented serially during the ISI, and

the participants are instructed to add them up and then remember the total throughout the

rest of the trial so that they can give this value when prompted to do so at the end of the

trial. Our assumption in designing this task is that the participants are engaged in complet-

ing the summat ion operations during the presentation of the second cue and that this

demand upon processing resources interferes with the form ation of within-compound asso-

ciations and thereby reduces retrospective revaluation relative to the control condition

Figure 1. Schematic diagram of the sequence events on a compound trial with (top line) and without (bottom

line) the interference task. Illustrated is the condition in which the treatment cue precedes the t arget cue on com-

pound trials, and the allergic reaction outcome is either omitted (“no reaction’’— top line) or presented (bottom

line). See text for further details.


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without the interfering task. Although our selection of this interfering task was primarily

based on empirical g rounds, it is well established that even simple mental arithmetic enga ges

the central executive component of working memory (e.g., Logie, Gilhooly, & Wynn, 1994;

De Rammelaere, Stuyven, & Vandierendonck, 1999).

A unique prediction of the associative theory is that the role of within-compound asso-

ciations is restricted to retrospective revaluation contingencies and does not contribute to

other selective learning effects, such as blocking. A blocking-like contingency can be pro-

duced by reversing the two stages of training so that exposure to the treatment cues pre-

cedes training with the compound cues (see Table 1). Pairing a treatment cue E with the

outcome in the ®rst stage should also attenuate or block the acquisition of the associative

strength by the target cue F with w hich it is paired in the second stage relat ive to the target

cue H whose treatment cue G is presented in the absence of the outcome in the ®rst stage.

Associative theories (e.g., M ackintosh, 1975; Pearce, 1987; Pearce & H all, 1980; Rescorla &

Wagner, 1972; Wagner, 1981) offer a number of different mechanisms for blocking, none of which appeal to within-compound associations. The Rescorla – Wagner variable reinforce-

ment rule (Rescorla & Wagner, 1972), for example, argues that increments in associative

strength are determined by the discrepancy between the combined strength of the cues

paired with the outcome and the total strength that can be supported by the outcome.

Pretraining the treatment cue ensures that this discrepancy is small when the target cue is

paired with the outcome during compound training, thereby attenuating the acquisition of

associative strength by the target cue.

Blocking contingencies provide a control condition against which to assess manipulations

that are predicted to affect retrospective revaluation selectively. The overall contingencies

between the target cues and the outcome are the same in the blocking and retrospective

revaluation conditions when aggregated across the two stages. Consequently, any variable

that selectively a ffects retrospective revaluation is not media ted by processes sensitive to the

overall contingency. Dickinson and Burke (1996) exploited this control by demonstrating

that the consistency of treatment – target cue pairings during compound training affected

retrospective revaluation but not blocking. We also included a blocking condition in the

present studies to assess whether any effect of the interference treatment is selective to

retrospective revaluation.The trial structure illustrated in Figure 1 differs from that employed in our previous

studies of retrospective revaluation (Aitken et al., 2000; Dickinson & Burke, 1996; Larkin

et al., 1998) not only in terms of the presence of the concurrent mental arithmetic task but

also in the use of serially presented cues with an ISI rather than simultaneously presented

cues. Consequently, in the ®rst experiment we determined whether retrospective revalua-

tion and blocking occur with serially presented cues in the absence of the interfering task.

Having established these phenomena with the serial procedure, the effect of the interfering

task on both retrospective revaluation and blocking was investigated in the last two studies.

EXPERIMENT 1

The design of the study is illustrated in Table 1. Each participant was trained concurrently

on the two retrospective revaluation contingencies, AB1A1 and CD1C2 and the two

blocking contingencies, E1EF1 and G2GH1. In addition, two ®ller contingencies,


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IJ2I2 and K 2KL2, were also presented. The cues from these ®ller contingencies were

never paired with the outcome and served the function of ensuring that the participants

encoded the identity of the speci®c food cues by requiring them to discriminate those paired

with the outcome from those that did not predict the outcome. In addition, we varied the

order in which the target and treatment cues were presented on compound trials by using

two pairs of food cues in each contingency. The target was presented after the treatment cue

for one pair (see Figure 1), whereas the order of the two cues was reversed for the second

pair.

In summary, each participant was trained concurrently on six contingencies. If serial

compound training supports retrospective revaluation, the D target cues from the CD1C2

contingency should have been rated as more causally effective than the B target cues from

the AB1A1 contingency. Correspondingly, blocking would have been manifest if the H

target cues from the G2GH1 contingency attracted higher causal ratings that the F target

cues from the E1EF1 contingency.

Method

Participants and stimuli

The participants were 12 members of the University of Cambridge who each received £2 for

participating in the experiment. Pictures of foods accompanied by the name of the food acted as the

cues in each contingency. Two pairs of treatment and target cues were assigned to each of the six

contingencies, thereby generating twelve pairs of cues. The first and second cues presented duringcompound training were, respectively: Pear and bread; cake and cheese; chicken and coffee; garlic

and ham; ice cream and lemon; margarine and mushrooms; banana and peaches; pork pie and rice;

steak and tomatoe s; green beans and aubergine; jam and flapjack; and leeks and tea. Assignme nt of

these two cue pairs to each contingency was rotated so that each compound appeared in each con-

tingency across the 12 participants. For example, both the pear – bread pair and the c heese – cake pair

acted as the AB cue compounds for one participant, whereas the cheese – cake pair and the

chicken – coffee pair acted as the AB cue compounds, respectively, for the next participant, and so

on. Within the two pairs of cues assigned to a contingency, the treatment cue (e.g., A) occurred as

the first cue (e.g., pear) of the serial compound, and the target cue (e.g., B) occurred as the seco nd

cue (e.g., bread). This ordering was reversed for the second pair in which the target cue (e.g., cake)

was presented first and the treatm ent cue (e.g., cheese) was presented second within the serial com-

pound. Each food retained its role as a target or treatment cue across subjects, albeit in different

contingencies. As a consequence, the order of the treatment and target cues in the serial compound

was counterbalanced across cues, although this counterbalancing was confounded with the role

taken by each specific food cue.

The food pictures were derived from photographs in magazines and scanned into an Acorn

RiscPC700 computer so that they could be displayed centrally on a 40-cm viewable diagonal Ilyama

colour monitor over an area of 12 cm 3 12 cm. The name of the food was also presented below the

picture (see Figure 1). The occurrence of the outcome was indica ted by the words “Allergic Reaction’’displayed centra lly in red w ith a surrounding red zigzag gra phic and accompanied by a 1-s sound. The

absence of the outcome was indica ted by the words “No Reaction’’ displayed centrally in green with

a surrounding green box graphic and a different accompanying 1-s sound.


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Procedure

At the start of the experiment each participant was given a sheet of instructions which were also

read out by the e xperimenter.

This is an investigation into how people, in general, form links between events. It should beemphasised that this experiment is not a test of your personal abilities or skills. Your name w ill

not be linked with a ny of the data. If anything is unclear in the following instructions, ask me,

and I can repeat points to you, but to prevent in¯uencing your performance, I cannot provide

any additional inform ation. In this experiment, you w ill assess the likelihood that certain foods

are able to cause allergic reactions. The ®rst part of the experiment is to gauge your initial views

of some foods. This is to check whether you hold any particularly extreme opinions of the foods

which will be used in the tests, which may affect your later performance. Using the opinion

scale, you can express your opinions about the foods on a scale of 0 to 8. Imagine an ordinary

individual, who is completely unknown to you, has been fed the following foods. After each food

is displayed, referring to the opinion scale, type in what you think is the likelihood that eating

these foods will cause an allergic reaction. The imaginary individual may not have an allergic

reaction to any foods and you should base your initial ratings on the fact that most people do

not suffer from allergic reactions, and that you know nothing about this individual. The pur-

pose of this test is to ®nd out whether you have any strong opinions of certain foods that may

affect your later judgements.

The pictures and names of the eight treatment cues and the eight target cues from the experimen-

tal contingencies and all the ®ller cues were then displayed one at a time in random order. A row of

keys on the computer keyboard corresponded to an attached scale showing the likelihood of an aller-

gic reaction occurring, ranging from 0 (de®nitely not) through 4 (possibly) to 8 (de®nitely). U sing the

keyboard, participants rated each cue from 0 to 8 after each presentation.

Participants then received another instruction sheet, which was also read out to them:

Now im agine that you are an allergist, someone who tries to discover the cause of allergic reac-

tions in people. You have just been presented with a new patient, “Mr. X ’’, who suffers from

allergic reactions following some meals, but not others. In an attempt to discover which foods

cause Mr. X to have allergic reactions, you arrange for him to eat various foods for a meal on

each day, and observe if he has an allergic reaction or not. The meals that you give him are com-

posed of either one course of one food, or of two courses, each of one food, given to Mr. X one

after the other.

The computer will display to you the food he has for each meal. If the meal is composed of

only one course, only one food will be displayed. If the meal is composed of two courses, you

will see the food he had for the ®rst course followed by the food he had for the second course.

After each presentation, please predict with a “yes ’’ o r “no ’’ on the marked keys, whether you

think that your patient, Mr. X, will suffer an allergic reaction after eating this meal. You will

then be told by the computer whether or not an allergic reaction actually occurred.

Speed of response is not im portant, so take as much time as you need before responding.Obviously, at ®rst you will have to guess, as you don ’t know anything about your patient, but

hopefully, as you cont inue to be presented with meals, you will begin to learn which foods cause

allergic reactions.


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After this is complete, you will be asked to re-rate the foods, using the opinion scale above

the m arked keys, as before, but now you will rate the foods for their effect on “Mr. X ’’. You will

receive more information about that nearer the time.

Participants were then exposed to the two stages of training outlined in Table 1. To recap, two food

cues (e.g., pear and cheese) played the role of each contingency cue (e.g., A) and each ®ller cue (e.g.,

I). Stage 1 consisted of three blocks each of 18 trials. The blocks were composed of two presentations

of each of the two compound cues from the two retrospective revaluation contingencies (AB1 and

CD1), all paired with the outcome, and two presentations of each of the two ®ller compounds (IJ2)

presented without the outcome. Interspersed among these trials were single presentations of each of

the two treatment cues from the two blocking contingencies. One pair of treatment cues was paired

with the outcome (E1), whereas the other pair of treatment cues was presented without the outcome

(G2). In addition, each trial block contained a presentation of the two single ®ller cues without the

outcome (K 2). Stage 2 wa s identical to the ®rst stage except that the com pound cues were those from

the blocking contingencies and the treatment cue presentations those from the retrospective revalua-tion contingencies. Across the two stages, therefore, each participant received six presentations of each

cue compound from the four contingencies and three presentations of each treatment cue.

The sequence of events on compound trials is illustra ted in Figure 1. Each food cue was presented

for 1.5 s. On compound trials, the ®rst and second cues were separated by a 2-s ISI during which a

blank white screen was presented. To recap, for one of the pairs of food cues assigned to each cue

compound, the treatment cue was presented ®rst and the target cue second, whereas the order was

reversed for the other pair of food cues. Imme diately following the presentation of either the cue com -

pound or the treatment cue alone, the prompt “Allergy?’’ was presented centrally. Participants then

predicted whether the outcome would or would not occur by pressing the appropriate button on thekeyboard. Each predictive response was followed imm ediately by presentation of the appropriate out-

come screen for 2.5 s with accompanying auditory feedback. The outcome was represented by the

presentation of the words “Allergic Reaction’’ in red, with surrounding red border, whereas absence

of the outcome was represented by the central presentation of the words “No Reaction’’ in green with

surrounding green border. Following the presentation of an outcome screen, participants were

required to press the spacebar to present the next tra ining trial.

After the last trial of Stage 2, participants were given another sheet of instructions which we re also

read to them:

Now using the opinion scale above the numbered keys, as before, please re-rate your opinion of

the original foods that were presented to you, as to whether they cause allergic reactions. Now

your ratings will be for the effect of the foods on “Mr. X’’, in light of the data you have just seen.

The 24 (8 treatment, 8 targ et, and 8 ®ller) cues were then presented in random order, and partici-

pants typed in their responses, as before, on a scale of 0 to 8. Finally participants were thanked for

their cooperation, and any questions that they had were answered.

Results

Acquisition

Figure 2 illustrates the percentage of trials on which the participants predicted that the

cues would cause an allergic reaction by giving a “yes’’ response in each trial block. The

upper panel illustrates the predictive responses for the retrospective revaluation contin-


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gencies and the corresponding ®ller cues, whereas the lower panel shows the equivalent datafor the blocking contingencies and the corresponding ®ller cues. In both cases, the predic-

tive responses adapted to the prevailing contingencies. All participants gave fewer “yes ’’

responses to the ®ller compound cues than to the compound cues from the retrospective

revaluation contingencies by the end of Stage 1 and learned to discriminate between the

treatment cues on the basis of their relationship with the outcome during Stage 2. All par-

ticipants also showed the corresponding discriminative responding in the blocking condi-

tion, learning to discriminate between treatment cues in Stage 1 and between compound

cues in Stage 2.

Target cues

The results of most interest concern the way in which training under the different con-

tingencies affected the ratings of causal effectiveness of the target cues. These ratings are

analysed by a three-factor analysis of variance in which the condition factor distinguishes

Figure 2. Experiment 1: Percentage of trials in each block on which participants predicted the allergic reaction.

Upper and lower panels display the percentages for the retrospective revaluation (AB1A1 and CD1C2) and

blocking (E1EF1 and G2GH1) contingencies, respectively, and their associated ®ller contingencies (IJ2I2 and

K 2KL2). D o w n l o a d e d b y [ ] a t 0 6 : 2 5 1 6 A p r i l 2 0 1 5

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between the retrospective revaluation and blocking contingencies, and the contingency

factor distinguishes between the contingencies in which the treatment cue alone was paired

with outcome (AB1A1 and E1EF1) and those in which the treatment cue alone was

unpaired with the outcome (CD1C2 and G2GH1). Finally, the order factor contrasts

ratings when the treatment cue preceded the target cue on compound trials with those for

cues trained under the reverse order. Statistical reliability is assessed against a Type I error

rate of 0.05 or less.

The effect of order is signi®cant, F (1, 11) 5 10.52, M SE 5 5.57, re¯ecting the fact that

mean ra ting for the order in which the target cue was the second stimulus on the compound

trials (5.7) was higher than that for the order in which the target cue was the ®rst stimulus

(4.2). Importantly, however, this order factor interacts with neither of the other factors,

F s(1, 11) , 1.90, and consequently the ratings are collapsed across this variable for clarity

of presentation.

As the top panel of Figure 3 illustrates, both retrospective revaluation and blocking wereobserved in that the ratings for the target cues B and F from the contingencies in which the

treatment cues were paired with the outcome (AB1A1 and E1EF1) were lower than

those for the cues D and H from the contingencies in which the treatment cues were

unpaired with the outcome (CD1C2 and G2GH1), F (1, 11) 5 50.00, M SE 5 4.26. This

contingency factor does not interact with condition, F (1, 11) 5 1.39, however, suggesting

that the magnitudes of blocking and retrospective revaluation are similar. On average, the

Figure 3. Experiments 1 and 2: Mean causal ratings for the target cues from the retrospective revaluation

(AB1A1 and CD1C2) and blocking (E1EF1 and G2GH1) contingencies in Experiment 1 (top panel) and

Experiment 2 (bottom panel).


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ratings from the retrospective revaluation and blocking conditions do not differ reliably,

F (1, 11) 5 3.21. The differences in the ratings of the target cues following training are not

compromised by initial biases. A comparable analysis of the initial ratings of the target cues

yields no signi®cant main effects nor any reliable interactions, largest F (1, 11) 5 4.10. The

mean initial ratings of target cues from the retrospective revaluation contingencies

(AB1A1 and CD1C2) are: 2.1 for B; 2.2 for D; and from the blocking contingencies

(E1EF1 and G2GH1) they are: 2.2 for F; 2.0 for H.

Treatment cues

A comparable analysis carried out on the mean ratings of the treatment cues shows a sig-

ni®cant main effect of contingency, F (1, 11) 5 144.97, M SE 5 6.90, re¯ecting the fact that

treatment cues presented with the outcome were rated higher than treatment cues presented

in the absence of the outcome. There are no other signi®cant main effects nor interactions,largest F (1, 11) 5 1.76. The mean treatment cue ratings for the retrospective revaluation

contingencies (AB1A1 and CD1C2) are: 7.5 for A; 0.5 for C; and for the blocking con-

tingencies (E1EF1 and G2GH1) they are: 6.9 for E; 1.0 for G.

Discussion

This study replicates previous demonstrations of the blocking and retrospective revaluation

of causal judgements and extends these phenomena to procedures in which the treatment

and target cues are presented sequentially. We detected no effect of the order in which these

two cues are presented on compound trials on the ma gnitude of blocking and retrospective

revaluation, although there might be grounds for expecting an effect of this variable in the

latter condition. To recap, according to the associative account of retrospective revaluation ,

the treatment cue activates a representation of the target cue through a within-compound

association, and this association was brought about by forward pairings with the treatment-

target cue order but backward pairings with the target – treatment cue order. There is exten-

sive evidence that forward pairings in general produce stronger associative learning (see

Ekstrand, 1966; M ackintosh, 1974, for reviews), and, consequently, the revaluation might beexpected to be greater with the treatment – target cue order than with the reverse order. It

should be noted, however, that backwards pairings can support excitatory conditioning

(Spetch, Wilkie, & Pinel, 1981) and hum an associative learning with both traditional paired-

associate procedure (Ekstrand, 1966) and pictorial stimuli more akin to those used in the

present studies (Gerolin & Matute, 1999).

Moreover, forward pairings may not be the optimal temporal relationship for establish-

ing within-compound associations. Using animal conditioning procedures that controlled

for generalization decrement, Rescorla (1980) reported that simultaneous pairings produce

stronger within-compound associations than do either forward or backward pairings. This

®nding raises the possibility that our participants effectively transformed both the forward

and the backward pairings into simultaneous pairings by rehearsing the identity of the ®rst

cue of the compound throughout the ISI. If this is so, strong within-compound associations

should be formed under both cue orders, and retrospective revaluation is anticipated in all

conditions. It should be noted, however, that the order of the cues did affect the overall


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ratings for the target cues, with higher ratings being assigned when the target cues were

placed second in the compound. This effect probably re¯ects the difference in the tempora l

contiguity between the target cues and the outcome in the two orders, a factor that has been

shown previously to in¯uence causal judgement (e.g., Shanks, Pearson, & D ickinson, 1989).

EXPERIMENT 2

In Experiment 2, we attempted to interfere with the formation of within-compound associ-

ations by requiring the participants to perform a concurrent mental arithmetic task during

compound trials (see Figure 1). If retrospective revaluat ion, but not blocking, is mediated

by within-compound associations, the interference task should reduce the magnitude of retro-

spective revaluat ion relative to blocking. In order to evaluate th is prediction, the participants

were trained on the identical contingencies to those administered in Experiment 1 (see Table

1). The only difference was that they were asked to perform a mental arithmetic interfer-ence task during the ISI on compound trials and following cue presentations on treatment

cue trials. We presented the interference task during tra ining of the treatment cues alone as

well as during compound training in order to minimize any generalization decrement

between these two stages. If compound and treatment cue training differed with respect to

the presence of the interference task, we were concerned that the transfer of the associative

strength of the treatment cue between these two stages may have been compromised,

thereby producing a reduction in both blocking and retrospective revaluation.

Method


Twelve University of Cam bridge undergraduates received £2 for participation in the study. The

stimuli and their counterbalancing and assignment to the role of treatment and target cues in the dif-

ference contingencies were the same as those in Experiment 1.

Procedure Once a gain, participants were given an initial rating test and then trained concurrently on the two

retrospective (AB1A1 and CD1C2) and the two blocking (E1EF1 and G2GH1) contingencies,

along with the two ®ller (IJ2I2 and K 2KL2) contingenc ies (see Table 1), before a ®nal ra ting test.

Sequential compounds of the treatment and target cues were paired with the outcome in one of the

stages, whereas the treatment cues were trained alone in the other stage, being either paired or

unpaired with the outcome. Experiment 2 differed from the ®rst study, however, in that participants

were presented with three numbers randomly selected between 1 and 9 during the 2-s ISI on com-

pound trials and during an equivalent 2-s period following presentation of the treatment cue on treat-

ment cue trials. Each number was presented for 0.57 s with an inter-number interval of 0.1 s.Following either the presentation of the second compound cue or the 2-s period after the treatment

cue alone, participants were prompted for their allergy prediction and received the appropriate feed-

back. Imm ediately after the feedback screen, the word “Total?’’ was presented centrally on the screen

(see Figure 1), and participants entered the total of the three numbers presented during that trial.

There wa s no time limit on m aking either response. The interference task was also presented on ®ller

cue trials.


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Two changes were made to the instructions to accommodate these procedural variations. The

opening line of the very ®rst set of instructions was changed to:

This is an investigation into how people, in general, form links between events, and how well

people can do two things at once.

Also, the following paragraph was added to the second set of instructions, immediately following the

second paragraph:

In addition to displaying the foods, the com puter will also display 3 numbers on each trial. Your

task is to add these numbers up. After you have predicted whether an allergic reaction occurs,

you will also be asked to type in the total of the 3 numbers you have just seen; try and be as

accurate as possible with your response.

In all other respects, the procedure wa s the same as that used in Experiment 1 .

Results

Acquisition

The upper and lower panels of Figure 4 illustrate the mean percentage of trials on which

participants predicted that the cues would cause an allergic reaction by giving a “yes ’’

response in each trial block for the retrospective revaluation and blocking contingencies,

respectively. In all contingencies the predictive responses adapted to the prevailing contin-

gencies, as in Experiment 1. The treatment cue discrimination s for the blocking cont ingen-

cies are somewhat more noisy than the comparable discriminations in Experiment 1 (see

Figure 2), but nonetheless did adapt to the prevailing contingencies. Examinat ion of dis-

criminative performance in the ®nal block of treatment cue training for the blocking con-

tingencies shows that during this training block 11 out of 12 participants responded “yes ’’

more often to cues presented with the outcome than to cues presented in the absence of the

outcome. All participants achieved this differentiation for the other discriminations.

Target cues

The bottom panel of Figure 3 illustrates the mean final ratings of the target cues. The

order of the target and treatment cues during compound training had no effects, either

main or interacting, on the ratings of the target cues, F s , 1, and consequently we have

collapsed the rating across this variable for presentation. A significant main effect of con-

tingency, F (1, 11) 5 13.41, M SE 5 7.16, confirms that on average the rating for the tar-

get cues B and F from the contingencies in which the treatm ent cues were paired with the

outcome (AB1A1 and E1EF1) were lower than those for the target cues D and H from

the contingencies in which the treatment cues were presented alone (CD1C2 and

G2GH1). What is also clear from Figure 3 and the significant Co ndition 3 Contingency

interaction, F (1, 11) 5 5.59, M SE 5 6.71, is that the magnitude of the blocking effect is

greater than that of retrospective revaluation. Indeed, analyses of the simple effects fail to

detect any reliable effect of contingency on the retrospective revaluation condition, F , 1,


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whereas the blocking condition yields a significant effect of contingency, F (1, 11) 5 22.58,

M SE 5 5.61.The ®nal target cues ratings were not contaminated by pre-existing differences. An

equivalent analysis of the initial ratings reveals neither signi®cant main effects nor signi®-

cant interactions, largest F (1, 11) 5 4.03. Mean initial ratings of target cues are: For the

retrospective revaluation contingencies (AB1A1 and CD1C2), 2.3 for B and 1.7 for D;

and for the blocking contingencies (E1EF1 and G2GH1), 2.6 for F and 2.2 for H.

Treatment cues

The absence of reliable retrospective revaluation does not re¯ect a failure to learn the

treatment cue – outcome contingencies during Stage 2. The ®nal ratings of treatment cues in

all experimental contingencies were in¯uenced by their pairings with the outcome, with the

cues that had been paired with the outcome rated higher than those presented without the

outcome. Mean ®nal ratings of treatment cues are: For the retrospective revaluat ion contin-

gencies (AB1A1 and CD1C2), 6.6 for A and 2.1 for C; and for the blocking contingen-

Figure 4. Experiment 2: Percentage of trials in each block in which participants predicted the allergic reaction.



K 2KL2).


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cies (E1EF1 and G2GH1), 6.3 for E and 1.9 for G. There is a signi®cant main effect of

contingency on these ratings, F (1, 11) 5 33.48, M SE 5 14.12, but no other main effects and

interactions are reliable, largest F (1, 11) 5 2.01.

Discussion

The important ®nding is that the addit ion of the interference task different ia lly affected

retrospective revaluation and blocking. Whereas a reliable blocking effect was observed in

the presence of the interference task, performing this task reduced signi®cantly the ma gni-

tude of the retrospective revaluation relative to blocking and rendered the effect unreliable.

These ®ndings contrast with the comparable retrospective and blocking effects observed in

the absence of the mental arithmetic task in the ®rst study. Taken together the pattern of

ratings observed across the two experiments accords with the prediction of an associative

account of retrospective revaluation that appeals to within-compound associations on theassumption that the arithmetic task interferes with the formation of such associations dur-

ing compound training.

There are, however, other accounts of the function of the interference task. For example,

the presentation of the arithmetic task on trials with the treatment cue alone in Stage 2

could have interfered with learning the Cue A – -outcome relationship in the AB1A1 con-

tingency, thereby reducing retrospective revaluation. However, this mechanism anticipates

that the interference task should also have interfered with learning the Cue E – -outcome

association in the E1EF1 contingency and therefore should have produced a comparable

reduction in blocking. An alternative account appeals to the fact that the associative expla-

nation of retrospective revaluation assumes that the presentat ion of the treatment cue alone

in the second stage activates or retrieves a representation of the associated target cue.

Because we presented the interference task on the trials with the treatment cue alone, this

task could have reduced retrospective revaluation by interfering with the retrieval of the tar-

get cues during Stage 2 rather than by preventing the form ation of within-compound asso-

ciation during the ®rst stage. We examined this explanation in Experiment 3.

EXPERIMENT 3

The aims of this study were twofold. The ®rst was to determ ine whether the selective decre-

ment in retrospective revaluat ion produced by the arithmetic task in Experiment 2 is due to

the presence of the task on the compound trials or on the trials with the treatment cues

alone. In order to address this issue, we trained three groups of participants concurrently on

the retrospective revaluation and blocking contingencies outlined in Table 1, as in the pre-

vious studies. The training conditions for the control group were the same as those used in

Experiment 1 in that the participants were not required to perform the concurrent arith-

metic task. The participants in the compound group, however, performed the arithmetic

task during the ®rst stage of training, whereas those in the treatment group performed the

task during Stage 2. As a consequence, the compound group received the arithmetic task

during the compound training of the retrospective revaluation contingencies but not during

training of the treatment cues. To the extent that this task reduces retrospective revaluation

by interfering with the formation of within-compound associations, revaluation should have


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been reduced for the compound group relative to the control group. Conversely, if the arith-

metic task interferes with the retrieval of the target cue representat ions during the training

of the treatment cues, the treatment group should have shown a smaller retrospective reval-

uation effect than the control group. Finally, on the basis of the previous studies we antici-

pated that the presence of the interference task should have had no effect on the magnitude

of blocking whether it occurred during the training of the treatment cues in the compound

group or during compound training in the treatment group.

The second aim was to assess directly the impact of the arithmetic task on the formation

of within-compound associations. After the participants had given their causal ratings, we

asked them to recognize the target cues that had been paired with each treatment cue dur-

ing compound training. To the extent that the arithmetic task interferes with the formation

of within-compound associations, the recognition of the associated target cues should be

reduced in the compound and treatment groups relative the control group.

Method


Thirty-six University of Cam bridge undergraduates received £3 for participation in the study, and

were assigned at random to the three groups (n 5 12). The stimuli and their counterbalancing and

assignment to the role of treatment and target cues in the different contingencies were the same as

those used in Experiment 1.

Procedure

As in the previous studies, participants were given an initial causal rating test and then trained con-

currently on the two retrospective revaluation (AB1A1 and CD1C2) and the two blocking

(E1EF1 and G2GH1) contingencies along with the two ®ller (IJ2I2 and K 2KL2) contingen-

cies (see Table 1), before a ®nal causal rating test. Sequential compounds of the treatment and target

cues were paired with the outcom e in either the ®rst stage (retrospective revaluation contingencies) or

second stage (blocking contingencies), whereas the treatment cues were trained alone in the other

stage, being either paired or unpaired with the outcom e. As the order of the treatment and target cues

had no in¯uence on causal ratings in the previous studies, the treatment cues were always presented

as the ®rst course of the compound meals and the target cues as the second course.

Participants in the compound group were asked to perform the arithmetic task used in

Experiment 2 during the ®rst stage of training, in which they received the compound trials from the

retrospective revaluation contingencies and the treatment-alone trials from the blocking contingen-

cies, but not durin g the second stage in whic h they received the treatment-alone trials from the

retrospective revaluation contingencies and the compound trials from the blocking contingencies. By

contrast, we asked the treatment g roup to perform the arithmetic task during the second but not the

®rst stage of training. Therefore, these participants performed the addition task during the training

of the treatment cues from the retrospective revaluation contingencies and the compound cues from

the blocking contingencies. Finally, the arithmetic task was not presented to the control group at any

stage of training.

The differing procedures for each group required some m inor alterations in the instructions from

those employed in Experiment 2. Im mediately following the instructions about the arithmetic task, all

participants were informed that:


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The instructions for each stage of the experiment will tell you whether numbers will be pre-

sented during that stage. Num bers will be presented on all trials, or no trials in each stage.

The participants were then informed prior to each stage that “The computer will display three

numbers imm ediately following the ®rst course of every meal during this stage’’ or “The computer

will not present any numbers during this stage’’.

Following the ®nal causal rating test, we gave a recognition test to assess whether the treatment

cues retrieved the target cues with which they were paired in the compound meals under the follow-

ing instructions:

You will now be presented with another selection of foods, each of which made up one of the

courses of the meals given to M r X. Your task is to remembe r what the other course was in that

meal. As each of the courses is presented, referring to the cards with the pictures of the foods

on them, please type in the number of the food which you think was the other course in the

meal given to Mr X . Speed of response is not important, so take as much time as you like torespond.

Prior to these instructions, we gave the participant two A4 cards, each showing 12 numbered pic-

tures of the food cues. The pictures were numbered in a manner that did not re¯ect their pairings,

with the following cues being numbered from 1 to 24, respectively: Aubergine, banana, bread, cake,

cheese, chicken, coffee, ¯apjack, garlic, green beans, ham, ice cream, jam, leeks, lemon, margarine,

mushrooms, peaches, pear, pork pie, rice, steak, tea, tomatoes.

The recognition test consisted of a single presentation, in random order, of each treatment cue and

the ®rst cues of each of the ®ller compounds. Presentation was similar to the causal ratings test withthe text presented above the cue changed to “Other course?’’. Therefore, on each trial, the part icipant

was required to type on the numeric keypad of the computer the number of the food cue, which was

displaye d o n t he cards, tha t they rec ogniz ed a s t he other c ourse of the m eal tha t include d the food

presented on the m onitor.

In all other respects, the procedure wa s the same as that used in Experiment 2 .

Results and discussion

We excluded the rat ings of two participants, both from the control group, who volunteeredthe information that they suffered from allergies themselves and that this had in¯uenced

their ratings.

Acquisition

The upper panel of Figure 5 shows the predictive responses to cues from the retrospec-

tive revaluation contingencies and the corresponding ®ller cues, whereas the lower panel

displays the equivalent data for the blocking contingencies. As in the previous studies, the

predictive responses adapted to the prevailing contingencies with all participants giving

more “yes’’ responses to compound cues presented with the outcome than to the com-

pounds presented in the absence of the outcome over the ®nal two blocks of each stage.

However, 5 of the 34 participants failed to achieve the same differentiation for one set of

treatment cues: two participants in the control group for the blocking contingencies, one

from the treatment group for the retrospective revaluation contingencies, and two from the


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compound group — one for the blocking and the other for the retrospective revaluation

contingencies.

Target cues

We analysed the ®nal causal ratings of the target cues separately for the retrospective

revaluation and blocking contingencies by a mixed analysis of variance. The between-

participant group factor distinguishes between the ratings of the three groups, and the

within-participant factor of contingency distinguishes between the ratings of the target cues

trained in compound with the treatment cues that were paired and unpaired with the out-

come. As the top panel of Figure 6 shows, all groups exhibited a substantial blocking effect

in that the ratings for the target cues F from the E1EF1 contingency were substantially

lower than those for the target cues H from the G2GH1 contingency, F (1, 31) 5 59.66,

M SE 5 2.45. Importantly, the F ratio for the Group 3 Contingency interaction was less

Figure 5. Experiment 3: Percentage of trials in each block on which part icipants predicted the allergic reaction.



K 2KL2). The percentages are shown separately for the control, compound, and treatment groups. D o w n l o a d e d b y [ ] a t 0 6 : 2 5 1 6 A p r i l 2 0 1 5

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than one, suggesting that the magnitude of the blocking effect was comparable in all groups,

and separate contrasts yield a reliable effect of contingency for each group, smallest F (1, 31)

5 14.89, M SE 5 2.45.The effect of contingency is also reliable in a comparable analysis of retrospective reval-

uation, F (1, 31) 5 13.36, M SE 5 3.18. In contrast to the blocking contingencies, however,

the bottom panel of Figure 6 shows that the magnitude of retrospective revaluation effect,

as assessed by the difference in the ratings for cues B and D, is small in the com pound group

but relatively large in the treatment and control groups. Although the Group 3

Contingency interaction was not reliable, F (2, 31) 5 1.02, separate analyses revealed a

signi®cant effect of contingency for the treatment and control groups, smaller F (1, 31) 5

5.25, M SE 5 3.18, but not for the compound group, F (1, 31) 5 1.18.

Comparable analyses of the initial causal ratings reveal no signi®cant main effects and

interactions, F s(1, 31) , 2.37 and F s(2, 31) , 1.94. The mean initial ratings of target cues

for the control, compound, and treatment groups are, respectively: For the retrospective

revaluation contingencies (AB1A1 and CD1C2), 2.0, 2.8, 1.8 for B and 1.3, 2.4, 1.9 for

D; and for the blocking contingencies (E1EF1 and G2GH1), 1.9, 2.0, 1.7 for F and 1.8,

2.1, 1.8 for H.

Figure 6. Experiment 3: Mean causal ratings for the target cues from the blocking (Cues F and H , top panel) and

retrospective revaluation contingencies (Cues B and D, bottom panel) given by the control, compound, and treat-

ment g roups.


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Treatment cues

The treatment cues that had been paired with the outcome were rated higher than those

presented without the outcome. Mean ®nal ratings of treatment cues for the control, com-

pound, and treatment groups are, respectively: For the retrospective revaluation contingen-

cies (AB1A1 and CD1C2), 7.4, 7.1, 6.8 for A and 0.7, 1.3, 1.3 for C; and for the blockingcontingencies (E1EF1 and G2GH1), 7.0, 7.0, 7.2 for E and 2.1, 2.3, 2.1 for G. There is

a signi®cant main effect of contingency on these ratings in both the blocking and the retro-

spective revaluation conditions, smaller F (1, 31) 5 95.52, M SE 5 2.30; but no other main

effects and interactions are reliable, F s , 1.

T reatment target cue recognition

The recognition scores from a participant in the treatment group who misunderstood thenature of the recognition test are excluded from the presentation and analysis, which are

therefore based on the perform ance of the remaining 33 subjects. Although, on average, the

recognition performance was lowest for the participants who received the arithmetic task

during compound training – -the compound group for the retrospective revaluation contin-

gencies and the treatment group for blocking contingencies – -in neither set of contingencies

is there a signi®cant effect of group, largest F (2, 30) 5 1.23. On average the percentages of

correct recognition of the target cues paired with each treatment cue for the control, com-

pound, and treatment groups are, respectively: For the retrospective revaluation contingen-

cies (AB1A1 and CD1C2), 52.5, 35.4 and 50.0; and for the blocking contingencies(E1EF1 and G2GH1), 62.5, 47.9 and 40.9.

The failure to detect a reliable effect of the interference task on recognition of treat-

ment – target cue pairings that can be related to the causal judgements led us to re-examine

the relationship between recognition performance and causal learning using a post hoc cat-

egorization of participants. This categorization is based upon the relative recognition of the

retrospective revaluation and blocking compounds. Five participants showed equivalent

recognition scores for the retrospective revaluation and blocking contingencies and are

therefore excluded from the analysis. Of the remaining 28 participants, half (6 from thecompound group, 3 from the treatment group, and 5 from the control group) had higher

recognition scores for the cue compounds from the retrospective revaluation (RR) contin-

gencies (67.9%) than from the blocking (BLK) contingencies (35.7%) – -these participants

are designa ted Group RR .BLK. T he remaining participants (3 from the compound group,

6 from the treatment group, and 5 from the control group), designated Group BLK .RR ,

have higher recognition scores for cue compounds from the blocking contingencies (69.6%)

than for those from the retrospective revaluation contingencies (26.8%).

To the extent that retrospective revaluation is mediated by within-compound associations,

we anticipated that Group RR .BLK should have shown a larger revaluation effect thanGroup BLK .RR. By contrast, the magnitude of the blocking should not have differed

between groups if this effect is independent of the strength of the within-compound associ-

ations. Figure 7 shows that these predictions are ful®lled. There is a signi®cant Group 3

Contingency interaction for the retrospective revaluation contingencies, F (1, 26) 5 5.43,

M SE 5 2.49, and simple main effect analyses reveal that the target cue D from the CD1C2


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contingency was rated more highly than the target cue B from the AB1A1 contingency by

Group RR .BLK, F (1, 26) 5 17.11, M SE 5 2.49, but not by Group BLK .RR, F , 1. By

contrast, the F ratio for this interaction is less than one for the blocking contingencies, and

the target cue H from the G2GH1 contingency was rated more highly than the target cue

F from the E1EF1 contingency by both groups, smaller F (1, 26) 5 18.19, M SE 5 2.49.

In summary, the present study suggests that the arithmetic task interferes with retrospec-

tive revaluation when it is performed during compound training but not during trials with thetreatment cues alone. Moreover, the loss of retrospective revaluation was more pronounced for

participants with relatively low recognition of the treatment – target cue compounds from the

retrospective revaluation contingencies, suggesting that the revaluation is mediated by w ithin-

compound associations. By contrast, a reliable blocking effect was observed whether or not the

arithmetic task was performed during either compound or treatment cue training, and the

magnitude of the effect was unrelated to the relative recognition scores for the blocking com-

pounds. Taken together, these ®ndings suggest that blocking, unlike retrospective revaluation,

is unaffected by the strength of the within-compound associations.

GENERAL DISCUSSION

Experiment 1 replicated previous demonstrations of blocking and retrospective revaluation

in the acquisition of human causal judgements (Chapman, 1991; Dickinson & Burke, 1996;

Shanks, 1985; Wasserman & Berglan, 1998; Wasserman et al., 1996; Williams et al., 1994)

Figure 7. Experiment 3: Mean causal ratings for the target cues from the blocking (Cues F and H , top panel) and

retrospective revaluation contingencies (Cues B and D, bottom panel) given by Groups BLK .RR and RR .BLK.


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and extended these demonstrations to procedures in which the treatment and target cues are

presented in serial rather than simultaneous compounds. Although the serial order of these

cues during compound training had no detectable effect on the magnitude of either block-

ing or retrospective revaluation, performing an arithmetic interference task during the

inter-cue interval on compound trials abolished reliable retrospective revaluation in

Experiments 2 and 3.

We interpret this interference effect in terms of the role of within-com pound associations

within an associative account of retrospective revaluation. To recap, the presence of within-

compound associations enables the presentation of the treatment cue alone to activate a rep-

resentation of the associated target cue. If cue representations activated by within-com pound

associations have negative associability, the outcome conditions that normally support an

increm ent in associative strength will produce a decrement in the strength of the absent

target cue. Correspondingly, those outcome conditions that support an increment in associa-

tive strength for a presented cue will produce a decrement for an expected but omitted targetcue. These effects, either alone or in combination, serve to produce retrospect ive revaluation .

Thus, within this theory any operation that attenuates the formation of within-com pound

associations during training should also reduce the magnitude of retrospective revaluation.

We assume that the concurrent arithmetic task does this by interfering with the simultaneous

processing of the target and treatment cues during compound training, the condition that

favours the formation of within-com pound associations (Rescorla & Durlach, 1981). The

assessment of recognition of the treatment – target cue compound in the ®nal study provides

some support for this account. Although we could not detect a direct, reliable effect of the

interference task on recognition, the magnitude of the retrospective revaluation was smaller

for participants with relatively poor recognition of the compounds from these contingencies.

Without going into details, Dickinson and Burke (1996) considered the implementation

of negative associability within the context of three associative theories. The ®rst is the

modi®cation of the Rescorla – Wagner variable reinforcement rule (Rescorla & Wagner, 1972)

originally proposed by Van Hamme and Wasserman (1994) in which the negative associa-

bility is implemented by a negative learning rate parameter for that cue. In addition,

Dickinson and Burke (1996; see also Larkin et al., 1998) suggested a revision of Wagner’s

(1981) SOP theory, which draws a distinction between the state of a stimulus representationthat is activated directly and the state of one activated associatively. Dickinson and Burke

(1996) suggested that cue representations that are associatively activated support learning

but of the opposite type to that engaged by direct activation of a cue representation. Finally,

they also considered the implementation of negative associability in terms of negative acti-

vation of the cue unit of the connectionist learning system proposed by McLaren, Kaye,

and Mackintosh (1989), an application that has been developed by Graham (1999).

Whatever the relative merits of these different implementations of the role of within-

compound associations in retrospective revaluation, they all provide an account of blocking

that makes no appeal to such associations. In one way or another, these theories explain

blocking by assuming that an outcome predicted by a pretrained treatment cue will be less

effective in engaging excitatory associative learning than will an unpredicted outcome.

Thus, any procedure that minim izes within-compound associations, such as the presence of

an interference task on compound trials, should have a greater im pact on retrospective reval-

uation than on blocking.


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This is a crucial prediction that distinguishes associative accounts of causal learning

from the other main class of theory. This class is represented most recently by Cheng’s

(1997) Power PC theory, which provides an algorithm for interpreting contingency infor-

mation in terms of a concept of generative power (e.g., Michotte, 1946/1963) to yield

causal judgement. An important feature of this class of theory is that trial-order effects,

such as those that distinguish retrospective revaluation from blocking, lie outside the scope

of theory (see Cheng, 1997, pp. 381 – 384). Thus, in contrast to modi®ed associative

accounts, Power PC and related theories (e.g., Cheng & Holyoak, 1995) fail to address the

selective impact of the interference task in Experiments 2 and 3 and of the consistency of

treatment – target cue pairing in the Dickinson and Burke (1996) study on retrospective

revaluation but not blocking.

In summary, the present experiments provide further evidence for the role of within-

compound associations in retrospective revaluation and thereby point to a role for associa-

tive processes in causal learning. A variety of modi®ed associative theories offer processes of retrospective revaluation mediated by within-compound associations, and so are inseparable

on the present results. By contrast, non-associat ive models based upon the inferential inter-

pretation of contingency information provide no account of the differential effect of the

interference task on blocking and retrospective revaluat ion.

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M anuscr ipt rece ived 27 M arch 2000

Accepted revision rece ived 23 June 2000


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Aitken Et Al (2001)