Proctor2 Specs (programmer: Grant data analysis: Mozer)

General

This is an extremely simple program. We are just doing a 4-choice RT task, with a great deal of speed pressure. Period.

DESIGN

There are 20 blocks of trials with 50 trials per block. You select the stimulus randomly and independently from among 4 possibilities (Q V X or B). These four letters are mapped onto the responses V, B, N, M on the keyboard. There are no factors.

PROCEDURE

Present a plus sign before the first stimulus in a block. Thereafter, just present the letters. The letter should stay up until the subject responds. When they respond, take the letter away and wait 1000 msec before presenting the next letter. Do not provide feedback on each trial. At the end of each block provide feedback on mean RT for that block and each previous block so they can see how they are doing. Do not give them numbers on errors.

However, the program should check the subject’s error rate at the end of each block. If the error rate is < 10%, give them a large warning message saying “You are not going fast enough! Please try to respond faster on the next block!”. If the error rate is between 10% and 20%, tell them “You are going fast. Keep up the good work!”. If the error rate exceeds 20%, give them a message saying “We appreciate your going fast, but try to be a bit more accurate on the next block – very fast but accurate!”

INSTRUCTIONS

“You will see one of four letters on each trial: Q, V, X, or B. We want you to respond by pressing one of the four keys on the bottom row of the keyboard. So if you see a Q, you press the first key. If you see a V, you press the second key. And so on. Throughout the experiment, please keep your fingers rested on the keyboard. You should use the index and middle fingers of your left hand for the left two response keys, and the index and middle fingers of your right hand for the right two response keys.

We would like you to respond extremely rapidly. Try to be accurate, but the machine will insist that you respond so quickly you will make many errors. The experiment is divided into a number of blocks, each lasting just a minute or two. Between one block and the next, the computer will give you feedback on your performance.”

DATA STORAGE

Save the block and trial number, the stimulus presented, the response the subject made, the RT, and whether the response was accurate. That’s it.