P3D Re: short-term visual memory

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Sat, 6 Dec 1997 02:14:49 -0700
>From: Larry Berlin <lberlin@xxxxxxxxx>
>Subject: P3D Re: short-term visual memory

>>Date: Fri, 5 Dec 1997
>>John W Roberts writes:
>>
>>.............................
>>Regarding differences in visual memory among individuals, the ABC News Web
>>page had an article yesterday (don't know if it's still on), with a very
>>interesting animated demo of a test of the speed of visual memory. One of
>>the items claimed in the article is that humans have a lot of trouble
>>retaining more than about four items at once in their short-term visual
>>memory.
>>
>>Since viewing of a normal stereo photo consists in part of "scanning" a
>>scene and building up a mental model, that line of research might be of
>>interest to those who wish to design new stereo imaging systems.

>****  I would hate to buy a product engineered on that presumption. I figure
>the visual processing of the mind is more flexible than such generalizations
>make it out to be. The result of using such supposed properties, might be
>another of those irritating technical advances that in fact set us back a
>few years. There would be all sorts of problems getting anything
>sophisticated or full of action to work right on a screen that refuses to
>use more than four objects at a time.... I'd much rather put lots of stuff
>on the screen and leave it up to the viewer to keep track of however much
>they can...

You might want to check out the actual article - as of Tuesday, it's still
on the Web at:
http://www.abcnews.com/sections/scitech/visual/index.html

The article has an online demo to illustrate the point of the article.

I agree that it's a nuisance when people "over-interpret" studies and
guidelines, but it's also useful to be aware of the limitations when
designing for usability. The article didn't refer to four *static* objects -
when objects are static you can usually look at them one at a time,
consciously count them, etc. Judging from the article, the limitation appears
to be most apparent when you have moving or briefly visible objects, and the
type of observation you are doing requires that you be aware of all of them
at the same time.

For example, if you were to design a web page with three control buttons,
each marked by a whirling pattern of dots, with the only way to differentiate
among the buttons being that one has 9 dots, one 10 dots, and one 11 dots,
I expect that most people would have trouble telling which pattern was which.

Another example - if you glance at a group of similar stationary objects,
can you tell at a glance (without counting) how many there are? (No fair
putting the objects into a recognizable regular pattern.) With three or
four objects it's easy - with six or eight, it's pretty difficult. For that
particular skill, I suspect training can increase the count that is
immediately recognizable.

For 3D, the issues may not be exactly the same as the ones mentioned above,
but there will be other issues. For interpretation of moving 3D (or a
quickly-flashed still 3D photo) an issue may be whether the visual memory
is up to the task of holding and assembling enough 3D cues in the time
available, to build up a mental 3D model.

John R


------------------------------