Specs for SetTran2

This is like SetTran1, but instead of 2 possible stimuli, there are 4.

Everything is selected randomly and independently on each trial, as in SetTran1.

First, Experimenter is asked what order condition to use for the subject (1 or 2) as well as the usual questions.

At the beginning of the experiment, subject should get these instructions:

"Thank you for participating in this experiment. This experiment will be divided into twelve blocks of trials, each lasting just a few minutes. The task is very simple. On each trial, one of four possible stimuli will be presented. One stimulus is a yellow triangle. You always respond to the yellow triangle by pressing the X key with your left middle finger. Another stimulus is a blue diamond. You always respond to the blue diamond

by pressing the C key with your left index finger.

The third stimulus looks like a Stop Sign, the the fourth looks like a Green traffic light.

The diamond and triangle should be shapes about the same size as the stop sign and the green light.

One of these tells you to respond by pressing the m key with your right index finger. The other means DON'T RESPOND AT ALL. When the stimulus to RESPOND is presented, you should press the N key with the index finger of your dominant hand, responding as rapidly as possible. When the stimulus is the DON'T RESPOND stimulus, you should do nothing. The computer will tell you at the beginning of each block of trials which stimuli are associated with what response."

Task:

12 blocks X 50 trials/block

On each trial, pick one of the 4 stimuli random and independently. The probabilities

of each of the stimuli are:

yellow triangle: .4

blue diamond: .4

stop sign: .1

green light: .1

For subjects in order condition 1, use mapping 1 on blocks 1-6 and mapping 2 on blocks 7-12.

For subjects in order condition 2, use mapping 2 on blocks 1-6 and mapping 1 on blocks 7-12.

At the beginning of each block, show the subject which stimulus is for RESPOND, and which is for DON'T RESPOND. Show them the actual stimuli with the appropriate labels right below them, and keep that up there for 5 seconds (10 seconds on the blocks 1 and 7, where they are just getting used to it).

Mapping 1:

yellow triangle: X key

blue diamond: C key

Stop Sign: M key

Green Light: Don't Respond

Mapping 2:

yellow triangle: X key

blue diamond: C key

Stop Sign: Don't Respond

Green Light: M key

When you present the stimulus, it should stay up until the subject responds (or 1000 msec when the proper response is no response). Save what stimulus was presented, what response they make, if any, and what the response time is (measured from stimulus onset).

Codes to use for responses:

1 correct non-response to nogo signal

2 incorrectly pressed M to nogo signal

3 incorrectly pressed some other key to nogosignal

4 incorrectly non-response to go signal (stop sign or green light)

5 incorrectly non-response to diamond or triangle

6 correct response to diamond or triangle

7 incorrectly pressed some other key to diamond or triangle

Test out the program by making a miniversion with just 10 trials per block instead of 50, and running yourself right through. Make sure the program is saving EVERYTHING so that all information about every trial could be reconstructed (what stimulus presented, what response made if any, RT for that response).

Please let me know if you have any questions.