[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 AbstractThe 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 contactIntroductionUntil 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. 2882005 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. 2892005 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 2902005 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: sentencesGrammatical units: key words; telegram style 26 slides 15 slides 850 words (incl. titles) 230 words (incl. titles) mean 32,7 words per slidemean 15,3 words per slidemean 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 be derived from the main points. Sometimes they are interesting to know, but not essential to learn for an exam. 2912005 IEEE International Professional Communication Conference Proceedings Figure 1. Eye contact modeTable 2. Example of the differences between the extensive and concise text support Spoken text: [...] You want to change behaviour. That intention does not always lead to the desired effect. How can that be? It is necessary to determine the nature of the behaviour we are speaking about. Normally we distinguish two kinds of behaviour: planned behaviour and automatic behaviour. Planned behaviour is behaviour we contemplate. We weigh up the pros and cons. Planned behaviour is the decision of people to get married, to get divorced or to start a study in Management and Technology. Approximately five percent of our behaviour is planned behaviour. The remaining 95 % is automatic behaviour. That is behaviour we do not consciously contemplate: we call it routine behaviour. If we had to contemplate every act or bodily movement when we are riding a bike then we would have tumbled down before long. If you would have to consider each morning what manoeuvres you have to make to get up, you would not leave your bed. But you just think I have to go to college and the funny thing is that you start a large series of automatic behaviour [] Concise support (one slide):Extensive support (three slides):Types of behaviour There are two kinds of behaviour: planned and automatic behaviour. Types of behaviour Planned behaviour Behaviour we contemplate [5%] Automatic behaviour No conscious contemplating [95%] Planned behaviour Planned behaviour is behaviour that we contemplate consciously Examples are the decisions to get married, to divorce or to study Management & Technology. 5% of all behaviour is planned behaviour. Automatic behaviour Automatic behaviour is behaviour we do not consciously contemplate. Routine behaviour. Examples are the acts that we have to perform to rise from bed every morning or the movements we have to make when riding a bike. 95% of all behaviour is automatic behaviour. A verification of the usability of the above informal definitions was carried out by two judges (not the authors), both of them communication trainers. They independently sorted the sentences of the extensive PowerPoint version in main points and details. This resulted in a reasonable agreement between them expressed in a Cohens of .72. In conclusion: with the use of these definitions the content of both PowerPoint presentations can be reasonably characterised. Experimental subjects The sample consisted of 280 first and second year students of Delft University of Technology (bachelor study: Electronic Engineering and Management & Technology). They followed a compulsory course in public speaking. The experiments were carried out at the beginning of the course: they hadnt had any tuition in the use of PowerPoint at that phase in the programme. Questionnaire (mc text/opinion questions) A three part questionnaire was developed to collect information on the subjects and to get an impression of the effect that the presentation had on them. Firstly, the students were asked to give an indication of the amount of foreknowledge they had on the subject of communication and behavioural change on a five point scale. Furthermore they were asked whether they thought that a lecture on this subject was necessary and interesting for this group of students (on a five point scale as well). Secondly, to measure the effect in information transfer through the lecture (with or without the visual support of text slides) we developed a multiple choice questionnaire with 30 items (Cronbachs = .75). The mc-questions related to 2922005 IEEE International Professional Communication Conference Proceedings the main points of the lecture as well as to the details. The information needed to answer the questions was of course incorporated in the spoken text of the lecture. A number of the answers could also be retrieved from the various text slides. The mc-questionnaire could be split up in three parts: a. spoken text only: the answer of 7 questions could only be retrieved from the spoken text, not from the slides b. extended version: the answer of 11 could also retrieved from a slide of the extended set c. both versions: the answer of 12 questions could also be retrieved from both sets of slides. A third part of the questionnaire contained statements (with an accompanying five point scale) to measure the attitudes of the students regarding the presenter, the presentation and (when suitable) the projected PowerPoint presentation. The statements concerned the professionalism of the speaker, the degree to which the lecture was captivating and the comprehensibility of the lecture. These three aspects are related to the informative and persuasive power of a presentation ([9]; [1]). The experiment The context of the research a course in public speaking implied that a situation was chosen that would be quite similar to a normal lecture. A laboratory approach would be less useful. To this end a lecture-like or conference-like kind of presentation was chosen: the lecture was presented by a teacher unknown to the subjects in order to prevent bias effects in a normal classroom. To make the independent variable presentationmode operational, two teachers were asked to participate. The first one (A) was asked to stick as closely as possible to the text we had written to guarantee that each group of students would hear the same lecture. This resulted in a somewhat dull presentation that was mostly read from paper. The presenter occasionally glanced at the changing slides (the apparatus was handled by one of the authors) and at the attending audience. This condition was called the Read aloud-condition. The second teacher (B) was instructed to make as much eye-contact with the audience as possible and to do the utmost to make a lively presentation. Although he had to stay close to the written text as well, he made small colloquial interjections like Im sure all of you have had similar experiences. This condition was called the Eye-contactcondition (see Figure 1).The students received the lecture with the explanation that it was a part of their regular course. They were told that the faculty staff was doing an educational experiment that necessitated combining training courses with formal lectures. This also explained why they had to fill in the questionnaire directly after attending the lecture. A week later the students were again asked to complete the (same) questionnaire. Afterwards they were debriefed on the experiment. Table 3 shows that the students appeared to have rather little prior knowledge on the subject, that they thought the given information somewhat interesting and that it was a useful addition to the public speaking course they were following. Table 3. Prior knowledge, interest and need Mode Priorknow-ledgeInterest Need Mean 2.63 3.37 3.52 N 164 164 164 ReadaloudSd. 0.852 0.873 0.917 Mean 2.62 3.50 3.57 N 116 115 115 Eye-contactSd. 0.851 0.882 0.795 Mean 2.63 3.43 3.54 N 280 279 279 TotalSd. 0.850 0.878 0.868 The group that attended the ReadAloud presentation did not differ from the EyeContact presentation on the variables under investigation (F(3, 275)=.528 p=.67 2p=.01). ResultsThe research design was a 2x3 design: two styles of presenting and three possible modes of supporting the presentation. The main dependent variable was the score on a multiple choice knowledge test. The maximum score was 30 correct answers; on average the students scored 18 (60.5%; in the remainder percentage scores will be used for easy reference) of the questions correctly (range 7-27). The test turned out not to be an easy assignment. At first a statistical multivariate analysis was applied. It turned out that there was a main effect for the way of presenting (F(1, 274)=8,06 p2005 IEEE International Professional Communication Conference Proceedings 2p=.10). There was no interaction (F=.395). Table 4 presents the differences that were measured directly after the presentation; Table 5 presents the differences that were measured one week later. Table 4. Presentation mode vs. presentation support variations directly after the presentationmode support N Mean* Sd. Without PPT 42 47.22 16.345Extensive PPT 72 61.20 14.343Concise PPT 50 58.33 11.785Read-AloudTotal 164 55.59x 14.158Without PPT 39 54.79 16.326Extensive PPT 29 65.06 13.733Concise PPT 48 62.57 16.159Eye- ContactTotal 218 60.80y 15.41 Without PPT 81 50,86a 16.673Extensive PPT 101 62.31b 14.211Concise PPT 98 60.41b 14.185TotalTotal 280 57.86 15.02 * mc-score (percentage correct answers) a/b superscript: difference is significant (p2005 IEEE International Professional Communication Conference Proceedings regard to aspects of the speaker, the presentation itself and the PowerPoint presentation (when applicable). The statements about the speaker and the presentation could be grouped under three conceptual different headings: Attractiveness, Comprehensibility and Credibility. Table 7 shows the differences between the groups. Table 7. Opinions on lecture Presentation mode:ReadAloud N Mean* Sd. Without PPT 41 2.03a 0.927Extensive PPT 71 2.65b 0.901Concise PPT 49 2.57b 0.770Attractivelecture 1Total 161 2.47 0.903Without PPT 41 2.76a 1.007Extensive PPT 71 3.41b 0.863Concise PPT 49 3.39b 0.571Comprehen-sible lecture 2Total 161 3.24 0.870Without PPT 41 2.66a 0.929Extensive PPT 71 3.12b 0.838Concise PPT 49 3.24b 0.548Speaker is qualified 3Total 161 3.04 0.816Presentation mode: EyeContact N Mean* Sd. Without PPT 38 3.17 0.890Extensive PPT 28 3.57 0.725Concise PPT 47 3.21 0.944Attractivelecture 1Total 113 3.28 0.884Without PPT 38 3.42 0.826Extensive PPT 28 3.75 0.536Concise PPT 47 3.72 0.550Comprehen-sible lecture 2Total 113 3.63 0.664Without PPT 38 3.53 0.692Extensive PPT 28 3.56 0.685Concise PPT 47 3.40 0.840Speaker is qualified 3Total 113 3.48 0.752# statements from the questionnaire * five-point scale 1: not at all 5: very much a/b subscripts designate a significant difference p2005 IEEE International Professional Communication Conference Proceedings Table 8. Opinions on PowerPoint presentation Presentation mode: ReadAloud Support N Mean* Sd. Extensive PPT 71 2.78 1.020Concise PPT 48 2.79 0.843PPTappropriate1Total 119 2.79x 0.949Extensive PPT 71 2.61a 0.941Concise PPT 48 2.14b 0.562Too much text, no time to read2 Total 119 2.42 0.839Extensive PPT 71 3.14a 0.930Concise PPT 48 2.71b 0.939Information from ppt3Total 119 2.97 0.954Presentation mode: EyeContact Support N Mean* Sd. Extensive PPT 28 3.39a 0,712Concise PPT 45 2.93b 0,830PPTappropriate1Total 73 3.11y 0,813Extensive PPT 28 2.61a 0,821Concise PPT 45 2.07b 0,609Too much text, no time to read2 Total 73 2.27 0,741Extensive PPT 27 2.72 0,836Concise PPT 45 2.69 0,881Information from ppt3Total 72 2.70 0,859* five-point scale 1: not at all 5: very much a/b subscripts designate a significant difference p2005 IEEE International Professional Communication Conference Proceedings extensive slides than the group that saw the concise support version. Questions of which the answers were to be found on both PowerPoint versions, were answered equally well by both support groups.1 Some reservation to the outcome is necessary. Maybe our breach of the 6x6 rule was not severe enough. We did put more text on the slides, but they stayed legible altogether. The characteristic nature of the field experiment it was carried out in the context of a real course in oral presentation skills - did not allow us to go to extremes. In summary: it seems that information that teachers deem important should be put on your slides as much as possible. Despite of a growing number of slides, despite of more crammed slides. Of course there will be a border that you dont want to cross. A return to the scanned book pages or tables - mostly induced by severe time constraints, but also from a lack of speakers responsibility - dont seem desirable to us. Still, speakers dont have to let the 6x6 rule slow them down like an old-fashioned chain-gang.Presentation mode A second issue in this research was the presentation mode. Two modes were loosely defined:- the read aloud mode, where the speaker takes pains to utter the text just as he or she has written it; occasionally faint glancing to the audience as a whole or sideways to the projection screen; both hands glued to the lectern; and with no small jokes or other interjections. [6] - the eye contact mode, where the speaker wants to speak the written text but at the same time tries to break free from it by making small interjections, while glancing to the various persons in the audience and making gestures with one or two hands (see Figure 1). 1 In an earlier stage of our research in this phenomenon, with smaller experimental groups, the results suggested that the concise group had the advantage. [4] When presented the answers on both types of slides, the concise group significantly outperformed the extensive group. We concluded back then that using concise text slides would be better than extensive ones, because although the extensive group got more information to see they performed less than the concise group. Larger experimental groups now tell a different story. Looking at your audience when you present a speech is a rather basic teaching advice in courses oral communication. Therefore, the results of the experiments are not very surprising. The ReadAloud speaker is judged less credible than the EyeContact speaker. A type of observation that is also made in all kinds of other social psychological research. Eye contact, for example, has been related to higher ratings of counsellor respect and genuineness [11]; LaCrosse found that counsellors who smiled, made eye contact, and gestured more often were perceived as more competent than counsellors who did these things less often. [14] Increased levels of eye contact are indicative of credible behaviour in the courtroom. [3] So looking at your audience helps to establish the benevolence a rhetorical schooled speaker is searching for. The research at hand makes also clear that it is more efficient pedagogical seen to work hard on a more audience orientated mode of presentation: students will appreciate the lecture more and they will find it more comprehensible. And most important - they will remember more of what you were learning them. The experiments suggest teachers who are not up to a more expressive kind of presentation mode, to use PowerPoint text slides in an extensive way. The students wont really like them, but they turn out to really need them. A post analysis shows that students who attend to a ReadAloud speaker with extensive PowerPoint text slides, have an advantage over students who listened to the EyeContact speaker who left his or her slides at home. The former group outperformed the latter with 61.2% to 54.8% good on the test (t(109)=2.143 p2005 IEEE International Professional Communication Conference Proceedings combined with a diagram. The written text appeared to hinder the comprehension of the multi media presentation, because of the diagram. A logical question is whether this phenomenon also arises in oral communication. Due to the fact that the combination of figures and text often occurs in normal presentations, it seems worth the effort for further investigations. References [1] B.A. Andeweg, J.C. de Jong & H. Hoeken. May I have your attention? Exordial techniques in informative oral presentations. TechnicalCommunication Quarterly 7(3), 1998. pp.271-284. [2] B.Y. Auger. How to Run Better Business Meetings: An Executive's Guide to Meetings that Get Things Done. St. Paul: Mining and Manufacturing Co, 1979. [3] P. D. Blanck, R. Rosenthal, A.J. Hart & F. Bernieri. The measure of the judge: an empirically-based framework for exploring trial judges' behavior. Iowa Law Review, March 1990. [4] W. Blokzijl, & B. Andeweg. De effectiviteit van tekstdias bij presentaties. In: L. van Waes, P. Cuvelier, G. Jacobs & I. de Ridder (red.). Studies in taalbeheersing 1. Assen: Van Gorcum, 2003. [The effectivity of text slides in oral presentations] [5] W. Blokzijl & R. Naeff. The Instructor as Stagehand: Dutch Student Responses to PowerPoint. Business Communication Quarterly,67 (1), 2004. [6] K. de Bot, P. de Quay-Peeters & R. Evers. English proficiency in lower secondary education: a cross-national comparison. First Report. Nijmegen: Department of Applied Linguistics, 2003. [7] M. Gellevij. Visuals in Instruction: Screen Captures in Software Manuals. Enschede: University Press, 2002. [8] P.J. Hager & H.J. Scheiber. Designing & Delivering Scientific, Technical and Managerial Presentations. New York: John Wiley & Sons, Inc., 1997. [9] H. Hoeken. Het ontwerp van overtuigende teksten: Wat onderzoek leert over de opzet van effectieve reclame en voorlichting. Bussum: Coutinho, 1998. [The design of persuasive texts: what research tells about effective marketing and public relation planning] [10] S. Kalyuga, P. Chandler & J. Sweller. Managing Split-attention and Redundancy in Multimedia Instruction. Applied Cognitive Psychology 13(4), 1999. p.p. 351-371. [11] E.W. Kelly Jr. & J.H. True. Eye contact and communication of facilitative conditions. Perceptual and Motor Skills, 51, 1980. p.p. 815820.[12] C.M. Koolstra.& J.W.J. Beentjes. Childrens vocabulary acquisition in a foreign language through watching subtitled TV programmes at home. Educational Technology Research and Development 47 (1), 1999. p.p. 51-60.[13] P.C. Kyllonen & R.E. Chrystal. Reasoning ability is (little more than) working-memory capacity?! Intelligence 14(4), 1990. p.p. 389-433. [14] M. B. LaCrosse. Nonverbal behavior and perceived counselor attractiveness and persuasiveness. Journal of Counseling Psychology,22, 1975. p.p. 563-566. [15] D. Leeds. PowerSpeak: the complete guide to persuasive public speaking and presenting. New York: Prentice Hall Press, 1988. [16] R.E. Mayer, J. Heiser & S. Lonn. Cognitive Constraints on Multimedia Learning: When Presenting More Material Results in Less Understanding. Journal of Educational Psychology, 93(1), 2001. p.p. 187-198. [17] G.A. Miller. The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information. PsychologicalReview, 63(2), 1956. 81-96. [18] R. Moreno & R. Mayer. Verbal Redundancy in Multimedia Learning: When Reading Helps Listening. 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PowerPoint Is Evil. On website Wired Magazine, September 11 2003. http://www.wired.com/wired/archive/11.09/ppt2.htmlAbout the Authors Wim Blokzijl, MA (1971) received a master's degree in applied linguistics at the University of Groningen, 1996. Since 1997 he has worked at TU Delft, where he co-ordinates and teaches courses on oral and written communication. He does research into the effectiveness of visual support at oral presentations, and into audience appreciation of PowerPoint. He regularly publishes articles on a variety of communication subjects. Bas Andeweg, PhD (1952) is assistant professor. He lectures on oral and written communication. Recently he has finished his Ph.D. project Theintroduction of speeches (together with Jaap de Jong of Leiden University), about different aspects of speech introductions; for example about the effectiveness of different kinds of introductions (www.deeersteminuten.nl). He publishes regularly on subjects in the fringe of human communication and internet technology. 299