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From: "Jim Whitehead" <ejw@cse.ucsc.edu>
To: "FoRK" <FoRK@xent.com>
Subject: CD player UI for toddlers
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Date: Wed, 4 Sep 2002 11:03:03 -0700
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So, like many young children, my daughter Tatum (age 21 months) *really*
likes music. She also likes to have control over her environment, and this
means she wants to be the one putting CDs into the CD player, and getting
the music playing.

By watching Tatum, I've discovered that you can learn a lot about UI design
from watching 21-month-olds use technology. There is definitely a market
niche for a toddler-friendly CD/MP3 player.

The CD player we have combines play and pause in a single button, but
doesn't provide *instantaneous* feedback that the button was pushed, instead
requiring you to wait until the music starts, 5-10 seconds. This is a UI
disaster. Since Tatum doesn't get feedback right away, she presses the
button again, thereby pausing the CD before it even plays. She'll only ever
get music if she presses the button an odd number of times. This happens a
surprising amount of the time, since she eventually hits the button again
when the music doesn't play.

For toddlers, pressing play must cause the music to start immediately,
within half a second, for the toddler to get the causality and not press the
button multiple times. As well, pressing the button multiple times shouldn't
change the semantics, like an elevator button. No matter how many times you
press, the elevator still comes to that floor. The play button needs to be
the same.

The back-hinged door mechanism feeding the CD into the player is also a UI
disaster for Tatum. Since the door hinges on the back, Tatum has to angle
CDs to put them in, and take them out. Putting CDs in isn't much of a
problem, but taking them out is. Since Tatum grabs CDs by the back edge,
that edge comes out first, hitting the lid. Tatum eventually forces and
wiggles the CD out, a process that's hard on the CD and the player (but
which hasn't yet resulted in the CD player being broken). Surprisingly, it
hasn't been a problem getting the CD hole onto the spindle -- Tatum seems to
understand this concept, and the CD load area geometry naturally guides the
CD.

Tatum's CD player also plays tapes and has FM radio. For a toddler, this is
a mistake. Tatum doesn't understand the need to flick a switch to put the
player into a specific mode. She understands putting a CD in, and pressing
the play button. She sometimes understands the buttons for advancing a song,
but uses them erratically. As well, the radio feature has both FM mono and
FM stero, a distinction totally lost on Tatum. Tatum only understands the
binary distinction of music/no music.

What would the ideal toddler CD player be like? It would immediately start
playing a CD after it was loaded. As soon as the CD load door was closed, it
would give some audible feedback. It would have a single large play button.
The other typical CD controls would be larger than normal, but at least half
the size of the play button, and located far away from the play button, so
there is no chance of them getting accidentally pressed on the way to play.
The play button would be a bright color that is different from the color of
the player, and different from the color of the other CD control keys. The
device would only play CDs, no other functions. The CD load area would flip
open at least 80 degrees. It should be small, approachable for a toddler. It
should be possible to repeatedly drop the player from a height of 1-2'
without affecting the player.

- Jim




