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Using Audiovisual Aids
Concepts

Positive Factors


Audio-visual techniques may well enhance your presentation, but, conversely, have the potential to detract from it if not correctly used. Always remember that you should use Powerpoint, overheads and the like with the specific intention of increasing the impact of your presentation, not just as a matter of course because how everybody else uses them! The following are correct uses of these techniques:

  • To provide an outline of your presentation which assists the audience in following the logical flow of information.
  • To display complex information, too complicated to comprehend if presented through spoken words rather than visually. Visual presentation here allows the audience to study the material for a period sufficient to allow comprehension. Obvious examples of this include the use of tables, graphs diagrams and pictures.
  • To illustrate visual material: photographs, radiographs, video clips, etc.
  • To enhance the aesthetic appeal of the presentation, but only if this does not distract from your primary aim of making information available to your audience as efficiently as possible.

Negative Factors


Inexperienced presenters may not be aware that audio-visual material has the capacity to detract from their presentation. Drawbacks associated with poor choice and preparation of material include:

  • Distraction (1).Your audience cannot read and listen simultaneously. If you provide them with visual overload, they will not listen to you. Similarly, if you distract them by continuing to impart important information verbally, they will be unable to concentrate on an important table, graph or diagram. The verbal and visual presentations must complement each other, and not compete.
  • Distraction (2). Too much material is confusing, the audience fails to follow the plot and may lose interest entirely.
  • Distraction (3) and irritation. Poor choice of colours, illegible text, incomprehensible diagrams and spelling mistakes both lose and annoy the audience. They spend more time thinking about the negative aspects of the visual presentation than they do concentrating on the subject itself.
  • Potential for technical failure. Software programmes which won't load and projectors that don't project can and frequently do ruin an otherwise good presentation.
  • Seduction (1). Inexperienced presenters are seduced into using material merely because it is available. They show radiographs or ECGs which are not essential to the case. They show three views of the same thing, where one would suffice. All this wastes time. Worse still is to show material which does not in fact demonstrate the point of interest, because of poor quality or failure to project in the auditorium.
  • Seduction (2). Presenters are seduced into using animations and special effects which distract the audience and soon become irritating. This is a particular danger with Powerpoint. Beware of text scrolling across the screen or appearing with clackety-clack typewriter sound effects etc. (One may admire Bill Gates for his technical wizardry and his financial skills, but this does not necessarily translate into good taste and artistic ability...)

Whatever form of audio-visual material you use, remember that it cannot compensate for a poorly planned presentation, inaudible speech or poor projection of yourself as an interesting and arresting speaker. Remember to make eye contact with the audience, and do not let you audio-visual material overshadow either your own personality or the persuasive power of your voice.

Use of Powerpoint Presentations

Properly used, this is an extremely powerful presentation tool. Important points to remember are:

Make your slides Legible and Comprehensible

1. Use a large, clear font, few words per line, well-spaced lines, few lines per page. Your slide must be legible from the back of the auditorium.

2. Use well-contrasting colours: light fonts (white, yellow, cyan, lime green) on a dark background (navy blue or black), or dark colours (dark blue, black) on a white background. Some colours do not project well on the data projector, beware of red, pink, green brown and orange in particular.

3. Remember that a sizable percentage of the population are colour-blind: do not use red and green as contrasting colours!

4. Use different colour to make your meaning more comprehensible, not as a work of art. Each colour should stand for something, and colour selection should not be random.

Limit the Information

Limit the amount of information available on each slide. For text slides, a handful of words is usually sufficient. Full sentences are redundant:

Your speech and your slides should complement each other - not be one and the same thing. Either put up a few words of text (headlining) and say a lot about them, or put up a lot of information and say very little, allowing your audience time to read and digest the information (particularly in the case of a numeric table).

In the following example, most of the information is redundant: it is information easily assimilated by listening. Indeed, the audience are distracted by the need to read it, and also by the need to interpret its significance. You could save them the trouble of reading by telling them the information, and what it significance is.

History

The following slide in contrasts summarises the information succinctly, immediately directing the attention to the salient points. In this way, the audience has time to listen to you, and to weigh up everything you say against a background of age, risk factors of alcohol, cigarettes and avian exposure.

History2

Never switch to the next slide before the audience has had time to digest the contents of the previous slide. If you do, this usually implies that your slide contained too much information. Rather spread the information across several slides.

 

Present the information in the most appropriate format: Text, table, graph or image.

Always remember that the facts of the case are not important in themselves, only important in that they allow one to deduce an important message or principle. Look at the following table:

 Date      12/3     15/3      16/3      18/3    23/3   
 Sodium    135  134  135  136  135
 Potassium      4.5  4.3  4.3  4.5  4.4
 Urea   34.2  26.6  20.4  16.6  5.5
 Creatinine   433  365  320  239  105

This table has only one purpose - to illustrate that the patient's renal function returned to normal 12 days after admission. There are however several problems here. It is complex and requires careful study, during which time you may as well not talk as nobody will listen to you while they puzzle over the table. And if you change to the next slide without actually stopping for at least 60 seconds' silent contemplation, you can guarantee that the audience will not have picked up on the fact that the renal function improved.

Note the following:

The first line requires mental arithmetic. The audience has to subtract one date from another to work out the time scale involved. Nor is the actual date important - the patient would have behaved the same in November as in March. Save them this arithmetic by replacing the first line with Day 1, 4, 5, 7, 12.

The sodium and potassium rows are entirely redundant. Values are entirely normal, yet the audience has to scan 10 values and check mentally against normal values to deduce this. Rather leave these lines out and, if necessary, say "Sodium and potassium were normal throughout the illness".

The central three columns are probably redundant too. The importance of this table is that it illustrates an apparent full recovery of renal function in 12 days. Perhaps it could be replaced by

 Day   1   12 
 Urea  34.2   5.5 
 Creatinine   433  105

Since it is a trend which is important, the information is actually better illustrated by a graph rather than a table. This clearly portrays the message - of a trend to improvement over 12 days - without any necessity to interpret numbers:

Graph 1

This graph makes it instantly clear to the audience that the renal function improved, and that it did so in 12 days.

Thus, choose between table and graph: in any situation, one is often more appropriate than the other. In either case, avoid redundant or unnecessary data.

A common mistake is to use the wrong type of graph. Line graphs - not bar graphs - should be used to illustrate trends, as in the case above. The following graph is not appropriate to show a change over time. Bar graphs are appropriately used to show differences in values between related categories - e.g. males vs females, cats vs dogs vs monkeys.

Chart 2

Similarly, a well-chosen photograph may replace many words. And remember, the word is replace, not duplicate! For example, if you show the following image, it is not necessary to have a text slide indicating that the skin changes are erosions, pigmentary changes and scarring.

Audiovisual

If you use a photo (or radiograph or histology image), remember that it is unhelpful to show repeated views of the same thing: it is the principle you wish to put across, not any specific detail.

Most importantly , if the image is of poor quality or does not project well, leave it out. Do not show it and then apologise that the audience cannot see it!

Use animations appropriately

Special effects becomes tiresome after a short while. Use them only to add value (not presumed aesthetic appeal) to the presentation. The most appropriate actions are where items of information appear sequentially, allowing the audience time to digest the underlying text or image before being presented with the new item - an overlay technique. Here an all-at-once appearance is most effective: avoid items which crawl across the page.

 

Use of the Overhead Projector

Many of the same suggestions apply to the overhead projector. s with slides, overhead transparencies are often distracting since it is impossible to listen and read ahead at the same time. The overhead projector is best used for important but finicky detail that is easier comprehended on reading and studying - particularly laboratory results. It can also be used to highlight important milestones in the development of your presentation and discussion - i.e. headings. Get in the habit of presenting most of the history and examination without overheads, or at most with a few bare headings only. Don't use overheads as prompts for yourself. Prepare some notes on paper (or on small cards) and use these to keep you on track if you mistrust your memory.

2. If you use overheads, obey the following rules:

1. Legible colours only - dark blue, red, green, black. Orange, brown and nearly empty pens of any colour are out.

2. Write neatly. Scribbles are an insult to the audience.

3. Is your writing large enough to be seen from the back of the room?

4. Avoid visual noise - i.e. anything that distracts from the impact of the message of the overhead. Don't use different colours for decoration - only to highlight particular aspects, e.g. abnormal as opposed to normal results.

5. Write less on overheads, not more. Preferably single words, not sentences. What you say and what the audience reads on the overhead should NOT be one and the same thing. Use your overhead to expand on your talk (e.g. "here are the lab results we received....") or let your talk expand on the overhead (e.g. PLEURAL EFFUSION. ARTHRITIS... "In my discussion, I intend concentrating on two aspects of interest in this case: the pleural effusion and the arthritis. Now effusions are not commonly encountered... etc.")

6. Put down the minimum necessary to get the point across. For example, if you wish to show that a patient's renal function improved, write 24 Aug: creat 453; 15 Sept: creat 122. Don't put down the daily intermediate values 432,403,357,344 etc as well. They add nothing.

7. Avoid "striptease" presentations with a piece of cardboard inching down the transparency, revealing tantalising glimpses of what's to come except when there's a particular surprise to be hidden from the audience, in which case it can be very effective


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