11

Visual Recognition of Visual Recognition of Objects, Faces, and Printed Objects, Faces, and Printed

WordsWords

The best of Farah, Ch. 5 & 6The best of Farah, Ch. 5 & 6

22

Are Faces Special? Are Faces Special?

Are these two faces the same or different?Are these two faces the same or different?

33

WELL!!!WELL!!!

Inversion effectInversion effect. Face recognition is more . Face recognition is more orientation sensitive than other types of stimuliorientation sensitive than other types of stimuliInversion decreases face recognition accuracy Inversion decreases face recognition accuracy by ~20%; object recognition accuracy by ~20%; object recognition accuracy decreases by ~2%.decreases by ~2%.

Well!

44

Infant face processingInfant face processing

Infants 2 – 3 weeks Infants 2 – 3 weeks old can imitate adult old can imitate adult mouth movementsmouth movements

Newborn infants Newborn infants (mean age = 43 min) (mean age = 43 min) follow face-like follow face-like patterns longer than patterns longer than non-face like patterns non-face like patterns (Johnson et al, 1991)(Johnson et al, 1991)

From Bruce & Young (1998)

55

How are faces processed?How are faces processed?

By a face processing module?By a face processing module?

By a general purpose visual recognition By a general purpose visual recognition system in whichsystem in which– faces are more sensitive to orientation than faces are more sensitive to orientation than

other objects and/orother objects and/or– faces are the first type of stimulus that a faces are the first type of stimulus that a

general purpose system is programmed to general purpose system is programmed to process. process.

66

Criteria for identifying separate Criteria for identifying separate processing systems (modules) processing systems (modules)

• Anatomical-Neural SystemsAnatomical-Neural Systems: Are : Are objects, faces, and words recognized in objects, faces, and words recognized in different parts of the brain? different parts of the brain?

• Functional independenceFunctional independence: Is our ability : Is our ability to recognize objects independent of our to recognize objects independent of our ability to recognize faces or words?ability to recognize faces or words?

• Information processingInformation processing: Do different : Do different modules process information in different modules process information in different ways?ways?

77

Anatomical-Neural Systems:Anatomical-Neural Systems:The Evidence The Evidence

““Face” cells in monkeysFace” cells in monkeys

ProsopagnosiaProsopagnosia

Brain damageBrain damage

Functional neuroimagingFunctional neuroimaging

88

Neural systemsNeural systems. “Face” cells. “Face” cells

Single unit recording in Single unit recording in monkey IT cortex. Up to monkey IT cortex. Up to 20% of cells near superior 20% of cells near superior temporal sulcus (STS) are temporal sulcus (STS) are “face” cells.“face” cells.Seem to be responsive to Seem to be responsive to configural properties configural properties (Configuration: the (Configuration: the relative position of relative position of elements of a thing, such elements of a thing, such as a face). as a face).

From Farah (2000)

99

Neural systemsNeural systems: Prosopagnosia: ProsopagnosiaDifficulty recognizing facesDifficulty recognizing faces

A case study: LHA case study: LH

At 18, severe head injury in car accident and At 18, severe head injury in car accident and subsequent surgery damaged temporal-occipital subsequent surgery damaged temporal-occipital (and other) regions.(and other) regions.

Great recovery, eventually earned two Masters Great recovery, eventually earned two Masters degrees, works, etc. degrees, works, etc.

Can’t recognize his wife or children, nor can he Can’t recognize his wife or children, nor can he recognize himself in a group photo or mirrorrecognize himself in a group photo or mirror

Rarely has problems recognizing objectsRarely has problems recognizing objects

Is not dyslexicIs not dyslexic

1010

A case study: LH A case study: LH (Farah et al, 1995)(Farah et al, 1995)Is LH’s ability to recognize faces Is LH’s ability to recognize faces

disproportionately impaired?disproportionately impaired?

Study photos of objects Study photos of objects and facesand faces

2-choice recognition test2-choice recognition testRecognition accuracyRecognition accuracy

FacesFacesObjectsObjects

LHLH 62% < 92%62% < 92% NormalsNormals 86% = 85%86% = 85%

From Farah ( 2000)

1111

LH and the inversion effectLH and the inversion effect

LH and 8 normal subjects LH and 8 normal subjects tested in a sequential tested in a sequential matching task; 300 trials: matching task; 300 trials: 150 upright, 150 inverted.150 upright, 150 inverted.– See unfamiliar face 1.5 sSee unfamiliar face 1.5 s– Brief ISIBrief ISI– See unfamiliar faceSee unfamiliar face– Make same/different Make same/different

judgmentjudgment

Percent CorrectPercent Correct

Up Up InvertInvert

LH LH 58% < 58% < 72% 72%

Controls 94% >Controls 94% > 82% 82%

LH showed an inverted LH showed an inverted inversion effect.inversion effect.

Demonstrates obligatory Demonstrates obligatory use of his damaged face use of his damaged face processing system processing system

Farah, Levinson, & Klein (1995)

1212

Neural SystemsNeural Systems: Brain damage: Brain damage

Had thought that prosopagonsia required Had thought that prosopagonsia required bilateral damage. But, recent studies reveal that bilateral damage. But, recent studies reveal that unilateral right hemisphere lesionsunilateral right hemisphere lesions lead to lead to prosopagnosia.prosopagnosia.Wide range of areas in occipital and ventral Wide range of areas in occipital and ventral temporal areas involved in face processing, with temporal areas involved in face processing, with the right hemisphere playing a dominant role.the right hemisphere playing a dominant role.Impaired object processing, but spared face Impaired object processing, but spared face recognition, more likely to be observed with left recognition, more likely to be observed with left hemisphere damage.hemisphere damage.

1313

Neural systems.Neural systems. Functional Functional neuroimagingneuroimaging

Kanwisher et al (1997): fMRI studyKanwisher et al (1997): fMRI studySubtraction procedure:Subtraction procedure:– Passive viewing of:Passive viewing of:

intact faces vs. objectsintact faces vs. objects intact faces vs. scrambled facesintact faces vs. scrambled facesfront-view faces vs. front-view housesfront-view faces vs. front-view houses ¾ view faces vs. human hands¾ view faces vs. human hands

– Consecutive matching of ¾ view faces vs. handsConsecutive matching of ¾ view faces vs. hands

Both objects and faces activated inferior temporo-occipital regions, with Both objects and faces activated inferior temporo-occipital regions, with face activation confined to the right fusiform gyrus.face activation confined to the right fusiform gyrus.

FFA: Fusiform Face Area (just behind the ear)FFA: Fusiform Face Area (just behind the ear)

1414

Kanwisher et al: Sample data. Kanwisher et al: Sample data.

11stst column: Sample column: Sample stimulistimuli

22ndnd column: Activation column: Activation in ROI (green box) S1in ROI (green box) S1

33rdrd column: Mean column: Mean percent signal change percent signal change in ROI (5 subjects).in ROI (5 subjects).

1515

Humans: fMRI (“BloodOxygenLevelDependent”) imaging

Fusiform gyrus face area(Haxby et al. 2000 Trends Cog Sci)

1616

Functional independenceFunctional independence: Dissociating : Dissociating face and object perception in patientsface and object perception in patients

Patient CK: Is alexic and Patient CK: Is alexic and agnosic for everything but agnosic for everything but faces. Although he could faces. Although he could identify the Archimbaldo identify the Archimbaldo painting as a face, he could painting as a face, he could not identify objects that not identify objects that made up the face.made up the face.

Patient WJ: Sheep farmer Patient WJ: Sheep farmer who had prosopagnosia for who had prosopagnosia for human faces could still human faces could still recognize sheep (e.g., his recognize sheep (e.g., his problem was restricted to problem was restricted to human faces)human faces)

1717

Functional propertiesFunctional properties:: How are face and How are face and object recognition systems related?object recognition systems related?

(a) All stimuli are processed first by one (a) All stimuli are processed first by one general system, and faces receive further general system, and faces receive further processing.processing.

(b) Faces and objects are processed by (b) Faces and objects are processed by independent systems operating in parallel. independent systems operating in parallel.

1818

FunctionalFunctional differences between differences between face and object recognitionface and object recognition

Humans are experts Humans are experts at human face at human face recognition.recognition.

Holistic face Holistic face representation?representation?

Diamond & Carey Diamond & Carey (1986): The inversion (1986): The inversion effect in dog expertseffect in dog experts

From Diamond & Carey (1986)

1919

Inversion effectInversion effect

First-order relational informationFirst-order relational information: How the parts of an : How the parts of an object or face relate to one another.object or face relate to one another.Second-order relational informationSecond-order relational information: How the spatial : How the spatial relations of the parts (i.e., first-order relations) compare relations of the parts (i.e., first-order relations) compare to the prototypical arrangement of those parts.to the prototypical arrangement of those parts.Inversion disrupts the processing of second-order Inversion disrupts the processing of second-order relational information, but not first-order relational relational information, but not first-order relational information.information.Inversion disrupts processing of faces more than Inversion disrupts processing of faces more than processing of other objects.processing of other objects.Faces have strong configural properties and are Faces have strong configural properties and are processed holistically. processed holistically.

2020

Are faces processed holistically or Are faces processed holistically or are they decomposed like other are they decomposed like other objects?objects?

Tanaka & Farah (1993) Tanaka & Farah (1993)

Participants trained to Participants trained to identify faces and housesidentify faces and houses2-choice recognition test 2-choice recognition test on parts in isolation and on parts in isolation and in whole object.in whole object.Faces: Parts recognized Faces: Parts recognized more poorly in isolation more poorly in isolation than in whole (.66 < .77).than in whole (.66 < .77).Houses: Equal Houses: Equal recognition of parts in recognition of parts in isolation and in whole isolation and in whole (.80 = .78).(.80 = .78). From Farah (2000)

2121

Holistic processing: A function of Holistic processing: A function of expertise? expertise?

People are experts at face recognition. They have been People are experts at face recognition. They have been making these within-category (subordinate) making these within-category (subordinate) identifications since birth.identifications since birth.People with expertise in other domains (e.g., birds, cars, People with expertise in other domains (e.g., birds, cars, dogs) process exemplars from those domains holistically dogs) process exemplars from those domains holistically and the FFA is activated when processing these stimuli.and the FFA is activated when processing these stimuli.

All evidence presented to date is correlational. A study All evidence presented to date is correlational. A study that compares the performance of participants randomly that compares the performance of participants randomly assigned to become experts in some domain and assigned to become experts in some domain and novices is needed to establish a causal relationship novices is needed to establish a causal relationship between expertise and holistic processing.between expertise and holistic processing.

2222

Experimental studies of expertise: Experimental studies of expertise: Becoming a Greeble expertBecoming a Greeble expert

From Farah (2000)

2323

Gauthier & Tarr (1997, 2002)Gauthier & Tarr (1997, 2002)

Students trained to categorize 30 Greebles at Students trained to categorize 30 Greebles at the family (5 families) and individual level until the family (5 families) and individual level until they could do both equally fast.they could do both equally fast.

Tested recognition of parts in isolation and in the Tested recognition of parts in isolation and in the whole Greeble using same/different task:whole Greeble using same/different task:

A typical trial: Fixation cross (500 ms), study Greeble A typical trial: Fixation cross (500 ms), study Greeble (1500 ms), pattern mask (200 ms), cue (name of (1500 ms), pattern mask (200 ms), cue (name of target part, 100 ms), test Greeble or isolated part, target part, 100 ms), test Greeble or isolated part, same-different response.same-different response.

2424

Gauthier & Tarr (1997, 2002)Gauthier & Tarr (1997, 2002)

Parts recognized better in the context of Parts recognized better in the context of the whole Greeble than in isolation for the whole Greeble than in isolation for both novices and experts.both novices and experts.

(2002). Activation in FFA correlated with (2002). Activation in FFA correlated with obligatory processing of all features obligatory processing of all features (holistic-inclusive processing).(holistic-inclusive processing).

2525

Gauthier & Tarr (1997, 2002)Gauthier & Tarr (1997, 2002)

They suggest: “An emerging hypothesis is that They suggest: “An emerging hypothesis is that the neural specificity seen for face processing is the neural specificity seen for face processing is due to the particular constraints of humans’ due to the particular constraints of humans’ extensive experience with faces… A correlate is extensive experience with faces… A correlate is that given similar constraints, nonface stimuli will that given similar constraints, nonface stimuli will recruit the same neural substrate. In other recruit the same neural substrate. In other words, the FFA may not be specific for faces per words, the FFA may not be specific for faces per se, but rather only for the operations we se, but rather only for the operations we typically, and by default, perform when typically, and by default, perform when perceiving faces” (p. 431, 2002).perceiving faces” (p. 431, 2002).

2626

Is there a module dedicated to the Is there a module dedicated to the processing of faces?processing of faces?

Currently, a hotly debated question. The evidence is not Currently, a hotly debated question. The evidence is not clear. Much more research is needed.clear. Much more research is needed.Farah and colleagues suggest that faces are processed Farah and colleagues suggest that faces are processed in a more holistic fashion than objects.in a more holistic fashion than objects.Gauthier and colleagues suggest that this type of holistic Gauthier and colleagues suggest that this type of holistic processing applies to all expert subordinate processing applies to all expert subordinate categorization of homogeneous stimuli.categorization of homogeneous stimuli.

Whoever is right, faces are important. Faces convey Whoever is right, faces are important. Faces convey information about personal identity, age, sex, gaze information about personal identity, age, sex, gaze direction, and emotion, information that is critical to direction, and emotion, information that is critical to social beings.social beings.

2727

What about printed words?What about printed words?

We cannot argue for built-in We cannot argue for built-in text processing module: text processing module: – Reading is evolutionarily recent. Reading is evolutionarily recent. – In contrast to the acquisition of In contrast to the acquisition of

spoken language, reading is spoken language, reading is taught.taught.

However, we can ask “How However, we can ask “How could the brain develop a could the brain develop a localized, dedicated system for localized, dedicated system for such an arbitrary and such an arbitrary and evolutionary recent category of evolutionary recent category of stimuli?” (p. 148).stimuli?” (p. 148). From Gazzaniga, Irvy, & Mangun (1998)

2828

Focus on Pure AlexiaFocus on Pure Alexia

Impaired visual word Impaired visual word recognition, despite recognition, despite intact auditory word intact auditory word comprehension, and comprehension, and the ability to “write” the ability to “write” and to recognize and to recognize visual patterns other visual patterns other than words.than words.Slow letter-by-letter Slow letter-by-letter reading reading

From Farah (2000)

2929

Explanations of Pure Alexia.Explanations of Pure Alexia.H1: Disconnection HypothesisH1: Disconnection Hypothesis

Reading involves associating visual Reading involves associating visual information in the visual cortex with information in the visual cortex with language representations in the posterior language representations in the posterior language areas. Alexia reflects damage to language areas. Alexia reflects damage to that connection.that connection.

Although the neuropathology is consistent Although the neuropathology is consistent with this hypothesis, it cannot explain with this hypothesis, it cannot explain letter-by-letter reading.letter-by-letter reading.

3030

Explanations of Pure Alexia.Explanations of Pure Alexia.H2: Visual Impairment HypothesisH2: Visual Impairment Hypothesis

Simultanagnosia: Disorder of simultaneous form Simultanagnosia: Disorder of simultaneous form perception.perception.Alexia due to impairment in the rapid visual Alexia due to impairment in the rapid visual perception of multiple objects or multipart objects perception of multiple objects or multipart objects (most noticeable during reading).(most noticeable during reading).Evidence:Evidence:– Some impairments in visual processing of line drawings, Some impairments in visual processing of line drawings,

simple letter matching, naming letters in isolationsimple letter matching, naming letters in isolation– Increased difficulty when required to process multiple Increased difficulty when required to process multiple

letters (even in a simple matching task)letters (even in a simple matching task)– Word length effect exacerbated by visual noise, Word length effect exacerbated by visual noise,

suggesting a perceptual effectsuggesting a perceptual effect

3131

The visual impairment hypothesis: The visual impairment hypothesis: A computational interpretationA computational interpretation

Multishape recognition problems Multishape recognition problems due to interference among due to interference among representations of separate representations of separate shapes. shapes. The more distributed the The more distributed the representation, the greater the representation, the greater the interference when two or more interference when two or more shapes must be represented shapes must be represented simultaneously.simultaneously.Alexics have lost cortex that Alexics have lost cortex that supports localist shape supports localist shape representations (minimizes representations (minimizes interference), which are important interference), which are important for recognition of multishape for recognition of multishape objects, especially words.objects, especially words.

3232

Explanations of Pure Alexia. Explanations of Pure Alexia. H3: Orthography-specific (Word form) H3: Orthography-specific (Word form)

Impairment HypothesisImpairment Hypothesis

Alexia due to loss of Alexia due to loss of high-level orthographic high-level orthographic representations of word representations of word forms (morphemes and forms (morphemes and words). words).

Alternatively, input from Alternatively, input from the letter recognition the letter recognition system to the word form system to the word form system is limited to one system is limited to one letter at a time.letter at a time.

From Gazzaniga, Ivry & Mangun (1998)

3333

Word Form Hypothesis cont.Word Form Hypothesis cont.

Positive evidencePositive evidenceRegion of extrastriate Region of extrastriate visual cortex specialized for visual cortex specialized for processing of words and processing of words and orthographically legal orthographically legal pseudo-words in contrast pseudo-words in contrast to nonletter strings of to nonletter strings of shapes.shapes.

Negative EvidenceNegative Evidence Some alexics show a word Some alexics show a word

superiority effect (WSE).superiority effect (WSE).

From Gazzaniga, Irvy & Mangun (1998)

3434

What is the Word Superiority What is the Word Superiority Effect?Effect?

Word Superiority Word Superiority Effect (WSE).Effect (WSE).

Letters recognized Letters recognized better when seen in better when seen in a word than when a word than when seen alone or in a seen alone or in a nonword string.nonword string.

Standard trialStandard trialSee letter string:See letter string:

W O R DW O R D_ _ _ D_ _ _ DO R W DO R W D

See pattern mask:See pattern mask:See 2-afc test:See 2-afc test:

_ _ _ D_ _ _ D_ _ _ K _ _ _ K

3535

Explaining the WordSuperiority Effect

3636

Goal:Goal: To simulate word processing using a To simulate word processing using a single structure and set of parameterssingle structure and set of parameters

Interactive Activation Model:Interactive Activation Model:– Three processing levels Three processing levels

(feature, letter, word)(feature, letter, word)– Connections within levels are Connections within levels are

inhibitoryinhibitory– Connections between levels Connections between levels

are excitatory and inhibitoryare excitatory and inhibitory

Basic Assumptions:Basic Assumptions:– Perception occurs in a Perception occurs in a

multilevel systemmultilevel system– Deeper levels of processing Deeper levels of processing

are accessed via intermediate are accessed via intermediate levelslevels

– Processing is interactiveProcessing is interactive– Information flow is continuousInformation flow is continuous

McClelland & Rumelhart (1981)

3737

IA: IA: The unit for the letter T in the first position of The unit for the letter T in the first position of a four-letter array and some of its neighborsa four-letter array and some of its neighbors

McClelland & Rumelhart (1981)

3838

IA Model, WSE, Pure Alexia and IA Model, WSE, Pure Alexia and H3: The Word Form HypothesisH3: The Word Form Hypothesis

Pure alexics who abandon letter-by-letter Pure alexics who abandon letter-by-letter reading show WSE.reading show WSE.

Suggests word form system intact for Suggests word form system intact for at least some pure alexics; consistent with at least some pure alexics; consistent with prelexical visual impairment. prelexical visual impairment.

Independent evidence from pure alexics Independent evidence from pure alexics who do not show a WSE also suggests who do not show a WSE also suggests general visual impairment.general visual impairment.

3939

Explanations for Pure Alexia. Explanations for Pure Alexia. H4: General visual impairment most H4: General visual impairment most

severe for orthographysevere for orthography

A hybrid hypothesis stating that pure alexia A hybrid hypothesis stating that pure alexia results from a general visual impairment which results from a general visual impairment which affects the perception of multiple shapes, affects the perception of multiple shapes, especially for letters.especially for letters.

Evidence:Evidence:– Neuroimaging data showing cortical areas Neuroimaging data showing cortical areas

specialized for processing word-like stimuli specialized for processing word-like stimuli – Patient data showing intact number recognitionPatient data showing intact number recognition– Artificial neural network research: self organization of Artificial neural network research: self organization of

letter area and abstract letter identities. letter area and abstract letter identities.

4040

Self-organizing artificial neural Self-organizing artificial neural networksnetworks

Strength of connections Strength of connections among units changes to among units changes to reflect the pattern of reflect the pattern of activity levels of the units activity levels of the units according to Hebb rule: according to Hebb rule: “Neurons that fire “Neurons that fire together wire together”together wire together”

Creates “letter area”Creates “letter area”

Self “abstract letter Self “abstract letter identities”identities”

4141

Polk, T.A. & Farah, M.J. (1995). Brain localization for arbitrary stimulus categories: A simple account based on Hebbian learning.

Brain damaged patients can show selective impairments in the processing of music relative to other sounds, in writing relative to other sensory motor functions of the hand, and so on.

This simulation examines the spatial segregation of letter and digits.

LETTER-DIGIT FUNCTIONAL LOCALIZATION

4242

Polk & Farah (1995): Polk & Farah (1995): Neural Network Neural Network

Simulation (Letter-digit functional localization)Simulation (Letter-digit functional localization)

State of the neural net after training under varying initial conditions. For each pair: activation when all 8 letters are present (left) and all 8 digits are present (right).

4343

How does it work?How does it work?Architecture designed to provide:Architecture designed to provide:– COOPERATIVE MECHANISM to produce clusters of activityCOOPERATIVE MECHANISM to produce clusters of activity– COMPETITIVE MECHANISM to inhibit multiple clusters of COMPETITIVE MECHANISM to inhibit multiple clusters of

activityactivity

Initial presentation of a stimulus “A”Initial presentation of a stimulus “A”– Pattern of activity in output layer random, reflecting random Pattern of activity in output layer random, reflecting random

weight of connections between input and output layers. Over weight of connections between input and output layers. Over time excitatory connections will produce clusters around active time excitatory connections will produce clusters around active units and these will drive down activity elsewhere via inhibitory units and these will drive down activity elsewhere via inhibitory connections, leading to one (or very few) clusters of activity.connections, leading to one (or very few) clusters of activity.

– Hebb rule strengthens connection between “A” and the active Hebb rule strengthens connection between “A” and the active output units and weakens connections from other inactive input output units and weakens connections from other inactive input units. “A” will subsequently be biased toward activating the units. “A” will subsequently be biased toward activating the same cluster, while other input units will activate other output same cluster, while other input units will activate other output units.units.

Initial presentation of a digit “6”Initial presentation of a digit “6”– Same process as above, except that the units activated by “A” Same process as above, except that the units activated by “A”

will be less active to the digit. The beginning of will be less active to the digit. The beginning of segregation/localization.segregation/localization.

4444

Letter “Pop out”: Letter “Pop out”: Some behavioral data Some behavioral data on the alphanumeric category effecton the alphanumeric category effect

Tested:Tested:– Canadian postal Canadian postal

workersworkers– US postal workersUS postal workers– US college graduatesUS college graduates

A visual search task:A visual search task:– finding a target letter finding a target letter

among other lettersamong other letters– Finding a target letter Finding a target letter

among digitsamong digitsPolk & Farah (1998)

4545

Visual Search: Pop-outVisual Search: Pop-out

Find the Letter “T”Find the Letter “T”

L L L L L L L L LL L L L L L L L L

L L L L L L L L LL L L L L L L L L

L L L L L L L L LL L L L L L L L L

L L L L L L L L LL L L L L L L L L

L L T L L L L L LL L T L L L L L L

L L L L L L L L LL L L L L L L L L

Find the Letter “T”Find the Letter “T”

7 7 7 7 7 7 7 7 77 7 7 7 7 7 7 7 7

7 7 7 7 7 7 7 7 77 7 7 7 7 7 7 7 7

7 7 7 7 7 7 7 7 77 7 7 7 7 7 7 7 7

7 7 7 7 7 T 7 7 77 7 7 7 7 T 7 7 7

7 7 7 7 7 7 7 7 77 7 7 7 7 7 7 7 7

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7

4646

How do dedicated neural systems How do dedicated neural systems arise?arise?

EvolutionEvolution. Only abilities that evolved can be carried . Only abilities that evolved can be carried out by genetically specialized brain regions.out by genetically specialized brain regions.LearningLearning. Learning modifies the brain (alters . Learning modifies the brain (alters connections between individual neurons). Can connections between individual neurons). Can learning create functionally specialized brain areas?learning create functionally specialized brain areas?

Pure alexia: “clearest evidence so far available for Pure alexia: “clearest evidence so far available for localization of a category of knowledge that is localization of a category of knowledge that is fundamentally arbitrary, lacks an evolutionary fundamentally arbitrary, lacks an evolutionary history, and is learned relatively late in life” (p. 173).history, and is learned relatively late in life” (p. 173).

4747

Current “Best Story”: Current “Best Story”: Two classes of Two classes of processing apply differentially to faces, objects, processing apply differentially to faces, objects,

and printed words.and printed words.

Objects processed by parts and holisticallyObjects processed by parts and holisticallyFaces processed holisticallyFaces processed holisticallyPrinted words processed in partsPrinted words processed in parts

From Gazzaniga, Ivry, & Mangun (1998)