# Test of MCT vs PCT

[From Bill Powers (960805.0800 MDT)]

Hans Blom, 960803:

This leads to the following proposal: Implement a cursor tracking
task based on the above "world" equation. In each trial, r is kept
constant. In each new trial, r has a new (random) value. This can
be implemented by keeping r constant for e.g. 50 time intervals of
0.1 seconds; this is a trial. The action a will, I assume,
stabilize within that period. After 50 time intervals, a new r is
presented for, again, 50 time intervals.

I'm not clear how we are supposed to "present" new values of r, except
through asking the human participant to select a new value. In a
tracking task, a person is controlling the relationship between a cursor
position c and a target position t. If the person selects the reference
condition "cursor on target," then the perception is the difference in
positions, p = t - c, and the reference condition is r = 0. If we asked
the person to establish a different reference condition, say r = 1 inch,
then the person would be keeping the perception in the state t - c = 1
inch. The cursor would be maintained 1 inch below, or to the left of,
the target. Do you mean that we should ask the person to switch from one
reference condition to another every five seconds? Or to pick a new
reference condition at random every five seconds?

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Best,

Bill P.