[IEEE IPCC 2005. Proceedings. International Professional Communication Conference, 2005. - Limerick, Ireland (July 7, 2005)] IPCC 2005. Proceedings. International Professional Communication Conference, 2005. - The effects of text slide format and presentational quality on learning in college lectures

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  • 2005 IEEE International Professional Communication Conference Proceedings

    0-7803-9028-8/05/$20.00 2005 IEEE.

    The Effects of Text Slide Format and Presentational Quality on Learning in College Lectures

    Wim Blokzijl Institute of Technology and CommunicationDelft University of Technologyw.j.blokzijl@tbm.tudelft.nl

    Bas Andeweg Institute of Technology and CommunicationDelft University of Technologyb.a.andeweg@tbm.tudelft.nl


    The traditional advice for using text slides is to limit text on each slide to a maximum of about six or seven lines and a comparable number of words per line. But is the advice never solidly based on research - really as good as it sounds? And does the way in which it is delivered - reading stiffly from the paper or presenting more lively affect the effectiveness of the visual support?

    In a large scale experiment three types of presentation were compared. They differed in the number of slides and in the amount and format of the information presented on each slide. The presentations were presented in two different ways that differed in the amount of eye contact with the audience and in intonation. The findings of the study indicate that the content and format of the text slides had a significant effect on the learning of the participants, but that communication style has a compensating effect.

    Keywords: presentation, PowerPoint, lecture, teaching engineers, text slides, 6x6 rule, eye contact


    Until a few years ago, it was not uncommon for presenters to prepare for a lecture by printing large parts of it on a single transparency. And although their audiences would have needed binoculars to read it, many presenters seemed to consider this a very suitable way of designing their visual support. Now, we have PowerPoint. A not entirely uncontroversial programme; many columns with

    titles like Does PowerPoint make you stupid? [22] - have already been written on the tediousness of PowerPoint presentations that consist of an endless string of slides, each containing a long list of bullet points. Still, advocates and critics of the presentation programme will agree on at least one point: legibility of presentation slides has improved remarkably. Audiences at PowerPoint supported lectures call this to the surprise of nobody one of the greatest benefits of the programme. [5]

    This implies that these days most lectures are in harmony with what presentation advisers propagate; they want presenters to limit the amount of information on slides. Dont cram the slide with information advise for example Hager & Scheiber. [8] Leeds is more specific by stating that each line should contain no more than six words. [15] Auger tops this advice up by adding that a transparency should contain no more than six lines. [2]

    This last rule of thumb known as the 6 by 6 rule - is a very common guideline in presentation advice books. Actually, the exact amount of words and lines that is recommended differs with different authors. Stallings for example, propagates the 7 by 7 rule: no more than 7 lines of type, no more than 7 words per line. [23] But most of the advice comes down to this: there is a maximum to the number of lines and words that should be on a slide. This maximum should not be overstepped. Quite the contrary - although most authors only state it indirectly, their advice implies clearly that less is better. The six words and lines are a maximum, not an amount that should be aimed for. To achieve this conciseness, presenters should use key words instead of complete sentences.


  • 2005 IEEE International Professional Communication Conference Proceedings

    One may wonder how presentation advisers come to their numbers. A possible source of the 7 by 7 rule - although not explicitly mentioned by the authors - is Miller, who argues on the basis of different pieces of research, that we can process no more than seven chunks of information (plus or minus two) at the same time. [17] Advisers, however, never refer to any research supporting this ubiquitous rule.

    Yet these kinds of common sense rules do not necessarily have to be correct. Some recent studies suggest that text slides either concise or elaborate can be counterproductive in specific cases. [10], [16], [18] Studied however were not common lectures, but multimedia presentations; presentations that were watched from behind a computer. Yet these presentations were designed in a way that made them similar to common presentations in many ways. Research into PowerPoint usage in real life presentations is missing. This seems a bit odd: as we stated before, PowerPoint does stimulate fierce discussions - often on an academic level; e.g. [24] - and what would be more logical than to prove ones point with a piece of scientific research. Yet, there seems to be no inclination to study the effectiveness of PowerPoint slides.

    These two factors the multimedia experiments and the ongoing PowerPoint controversy - motivated us to study whether visual (textual) support is effective at common presentations. So our research question is: to what extent do text slides help audiences at oral presentations to better remember and understand the message? In this paper we present the results of our research. Before we come to that, we will first discuss the results of the aforementioned recent studies.

    Recent multimedia studies At oral presentations, audiences usually receive visual as well as auditory information. According to dual coding theory, these two information flows are processed separately, respectively through the visual and the auditive channel. [19] Written text is considered to be visual information, because it is at first, anyway - being processed in the visual channel. Learning can take place if the audience can combine visual and auditive information to a coherent model. [16] In presentations, this is the case when a presenters visual support is directly related to his or her speech.

    It is however not sufficient when visual and auditive input are connected. According to limited capacity theory, our short term memory is quite small (e.g. [17], [20] and [13]); therefore, offering too much information will lead to a memory overload. At presentations, this can happen when a presenter talks too fast or when theres too much information on the slides. A consequence is that listeners will understand and remember less of the lecture.

    Limited capacity theory assumes the presence of only one short term memory, in which visual as well as auditive information is processed. Recent multimedia research questions this. (e.g. [7])

    Kalyuga, Chandler & Sweller studied to what extent short term memory overload occurs when a multimedia presentation is extended with written text. [10] Their experiment went as follows. All their experimental subjects were offered a graph in which characteristics of solder were reflected. This graph was built up in steps during the presentation, just as often happens in PowerPoint presentations.

    The subjects were divided into three groups. Each of them had the graph explained in a different way: Group 1 heard a spoken explanation through

    headphones. Group 2 saw a written explanation, by means of

    short texts that appeared on the screen next to the graph.

    Group 3 got the spoken explanation as well as the written one.

    Afterwards, all groups were tested on retention and understanding. The group that was given an oral as well as written explanation, turned out to perform worst; the group that was only given the oral explanation, performed best.

    Comparable research is described by Mayer, Heiser & Lonn. [16] They also studied the effects of written text as a part of a multi media presentation. The design of their experiment was almost the same as that of Kalyuga, Chandler & Sweller. An important difference however, was that their groups were not presented with a graph, but an animated film about the origination of lightning. At the same time, they heard a voice through headphones that provided an explanation of the film.


  • 2005 IEEE International Professional Communication Conference Proceedings

    The experimental subjects were divided into three groups: Group 1 saw the entire text, as it was spoken,

    word by word on a screen. Group 2 saw a written summary on the screen. Group 3 saw no written text at all.

    Afterwards, all groups were tested on retention and understanding. The result: the group that saw no text at all, scored best; differences between the other two were not significant.

    In both studies the authors explained their results with the limited capacity theory: the groups that saw text on the screen had to pay attention to the text and to the graph or film at the same time. This caused their visual short term memory to get overloaded. The authors designate this specific case of information overload: split attention. A form of overload that is taking place when an audience has to process a text as well as a graph or animation.

    The summarising text was effectively quite extensive; all sentences were shortened a bit, but were kept grammatically correct. Maybe the groups in question would have performed better, had the text been more concise.

    The third experiment that is relevant for this research, is of Moreno & Mayer. [18] It is a follow-up of the above-mentioned experiment conducted by Mayer, Heiser & Lonn. [16] Again, subjects were presented with an explanation about the origin of lightning. However, this time they were not shown an animated film. All subjects heard a voice through headphones that gave an explanation. The subjects were divided into two groups: Group 1 just heard a voice, and saw nothing. Group 2 heard a voice and saw the entire text,

    as is was spoken, on a screen.

    Afterwards, when tested on retention and understanding, the group that saw and heard the text outperformed the other group. The authors explain that this was due to the absence of pictures; this prevents the split attention effect from occurring. So theres less visual short term memory overload; in this case, written text enhances retention as well as understanding.

    Research design Purpose of the study

    The purpose of our own study was twofold. Firstly, we wanted to examine whether a speech accompanied by a PowerPoint presentation with text slides would result in a better information transfer. Secondly, we wanted to know to what extent the extensiveness of the text slides would affect the information transfer.

    We distinguished three presentation support conditions:1 a presentation without visual support (without

    ppt) 2 a presentation supported with concise text

    slides (consise ppt) 3 a presentation with extensive text slides

    (extensive ppt)

    Regarding the first question, we expected the groups that saw text slides to outperform the group that didnt. This would, after all, be consistent with the results of Mayer, Heiser & Lonn. [16] Our expectations on the second issue were according the standard (but never researched) dogma in literature: concise text slides will be more effective than extensive ones.

    A problem in setting up the experiment was the presenter. Presentation style could, after all, affect the effectiveness of the slides; a dull presenter would stimulate the audience to pay more attention to the slides, while a captivating one would attract more attention to the presenter. It is because of these considerations that we introduced a second independent variable, which we called presentationmode. Here we varied the presentation style in which the lecture was presented to the audience: reading from paper or presented in a more lively matter.

    Presentation A lecture was written and designed specifically for this research. The subject of this lecture was the application of persuasion techniques in communication. We expected this subject to be interesting for the intended audience: students in public speaking. The lecture had a length of 2140 words and took approximately 15 minutes to present.

    Visual support To support the lecture, two PowerPoint presentations were designed. One we called


  • 2005 IEEE International Professional Communication Conference Proceedings

    concise PowerPoint; the other was baptised extensive PowerPoint. The concise version was designed according the rules in the advisory literature; the extensive version did not follow those guidelines. The two PowerPoint presentations differed on the amount of content and consequently on the lay-out of the slides themselves. By choosing a large, 32 point letter font, we ensured that the slides were legible. Table 1 summarises the differences between the two versions.

    Table 1 shows that the extensive version of the slides contained over 3.5 times as much words as the concise version. The concise version follows the 6 by 6 rule: it stays well within the advised margins. We ourselves would compliment a student on this type of design (although we would strongly advise him or her to make use of graphs and pictures as well). The extensive version does not follow the standard presentation guidelines. Although the average amount of text is more or less within acceptable limits, some slides were clearly too crammed (eight lines, title excluded; lines consisting of ten words). In this version, complete sentences were used frequently keywords were almost exclusively used in titles. These sentences were not literal duplicates from the text that was spoken by the presenter.

    Table 1. Differences between PowerPoint support versionsExtensive support Concise support

    Grammatical units: sentences

    Grammatical units: key words; telegram style

    26 slides 15 slides

    850 words (incl. titles) 230 words (incl. titles)

    mean 32,7 words per slide

    mean 15,3 words per slide

    mean 6,1 lines per slide (excl. titles)

    mean 3,5 lines per slide (excl. titles)

    mean 4,6 words per line (excl. titles)

    mean 9,2 syllables per line (excl. titles)

    mean 3,5 words per line (excl. titles)

    mean 7,8 syllables per line (excl. titles)

    font: 32 point (Arial) font: 32 point (Arial)

    content: 45 main points content: 29 main points

    content: 20 details content: 6 details

    The difference that is made in table 1 between so-called main points and details was defined as follows (see Table 2 for an example of the differences between the two versions): Main points: A main point was defined as an important informative element of the text. An element a student would typically need to know for an exam. An element that he or she wants to memorize, like a definition. Main points are also the elements that aid in remembering those central informational points like words/sentences that clarify the text structure. Summaries (or repetitions of main points) were considered as main points too.Details: A detail was defined as an element that was of no or little importance the storyline. It has an illustrative, elucidative function: an example, an illuminating kind of information or an acknowledgment. Details can often...


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