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C00002 00002	There are several kinds of talks, and the various situations
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There are several kinds of talks, and the various situations
correspond to different purposes, goals, on the part of the speaker
and the audience.  In a continuing course, the instructor must
bear in mind his general course goals, and each lecture must fit into
this high-level plan.  In a technical seminar, it would be disastrous
to under- or over-estimate the level of expertise of the audience.
At a talk you're giving to get a job interview, the goals are
obviously quite different than if you've been asked to make a few
remarks upon accepting some award.  When you compose and edit your
talk, you must filter it past the goals: does it satisfy your goals?
 the audience's?

MY purpose in delivering talks -- at least, talks about my research
-- is to both convey knowledge, and to get the audience interested.
Recognizing that little knowledge can be permanently transferred
in an hour, I concentrate on motivating. If the listener gets
interested, he or she will talk to me in more detail, go and read
some articles on the project, and thus -- in TENS of hours --
acquire a grasp of what I'm working on.

How do you motivate an audience?  Part of it is to show them
some interesting results, to arouse their curiosity in HOW those
results were acheived, to convince them that there is some power
here if they're willing to study it.  Another part of motivating
is entertainment, both for its own sake and to assure the listener
that should he choose to pursue this, he'll find further material
which is comprehensible and enjoyable.

Be careful about jokes and puns: if they fail it's a real
disaster (unless you are skilled at appealing to the
audience for sympathy).  But a few good jokes can brighten a
talk tremendously.  Knuth's criterion for a good joke is
that it be TECHNICAL, that it require some detailed
understanding of the current material, in order to
get the joke.  
<<SLIDE: technical jokes>> I can think of a couple reasons for this:
(1) When we get the joke, we reward our own cleverness
-- and publicize it -- by laughing.  (2) As Koestler says,
the discovery of the jarring of two separate matrices of
thought is what creates the appreciation of humor, and in this
case we have two simultaneous such jarrings, one for the joke itself,
and one because the joke is highly relevant to the current discussion.

A technique which, like jokes, can work well or can backfire, is
asking questions of the audience.  It helps convert a passive
situation into an active participation.  An even more subtle technique
is to arrange your discourse, and even your slides, in such a way
that a particular question is just begging to be asked.  If 
that question is on several people's minds, and especially if
someone voices it, then it will be extremely effective when you
answer it, and in fact when that answer flows into the talk.

An excellent way to
motivate is to propose some little self-contained experiment
or demonstration they can try later, on their own, to confirm
a point of the lecture.

Most talks are delivered in such a routine way that any
variation at all is likely to sustain interest. Use visual
effects, especially props and complete demonstrations.
Get a few emergency tricks, in case you feel an audience
slipping away. Try dropping a rock, or asking people to
keep their eye on this point <<hand>>.
Try appealing to several senses (almost any recording in the
background is a novelty), try composing some of the above
or compounding them (3 slide projectors).
Cultivate gestures.  Point at the board a lot.  This is
effective even if what you point at is unrelated to what you're
saying.

Have an eccentricity.
 Chew tobacco, wear three piece suits,
or point at the board a lot.  

Look people in the eye often.
This establishes that you are talking with them, rather than
presenting material as if to a videotape machine.

Try to break down thenatural barrier that exists between
speaker and listener.  Walk toward the audience and away
from them, as well as left to right across the room.

Get physically close to any projected images. Aside from the
entertainment aspect, this has a god IPS justification: it
doesn't force people to divide their attention between you
and the screen.

Neat drawings and slides, particularly in color,
create the illusion that the lecturer is at least twice
as well organized as he really is.  After IJCAI, several
people came up to me and congratulated me for calculating
what material on each of my slides was supposed to be
legible, and what was intentionally illegible.

On the same point, carry a pipe or a half-empty coffee cup.
That way, if you get stuck, stop and think while puffing or
sipping.

Many of the entertainment heuristics had to do with mass 
psychology.  There are some more along those lines that
we should all know:

Avoid sparsely populated lecture halls.  Empty seats suggest,
whether true or not, that attendance is much lower than expected.
Just a few people forced to stand, on the other hand, suggests
the opposite. Steeply sloping halls are also bad, like Sch 7500.
They give the effect of standing at the bottom of the
grand canyon, lecturing to the stones.

A group is emotive in proportion to its size.  A huge
audience will have extreme positive and negative reactions.
There is a noticable difference even between 50 and 150
people.

If you get a deflectionary question, deflect it.  Don't allow
obstructionist questioners to drag you off your plan.  Talk
with them after the lecture, if they wish.