SuperFast1 Specs

Task

Letter -> Button choice reaction time

Stimuli = K 7 P 3

Responses = z x , . [respectively]

Stimuli are always selected randomly and independently on each trial.

Overall Sequence of Events

1. Present Instruction #1. Do 2 blocks of practice, each consisting of 80 trials. On each trial, present one letter, which stays up until subject responds. Response-Stimulus Interval = 800 msec. Feedback = 500 msec windows error tone (making total response-stimulus interval = 1300); no sound for correct response. Pause between blocks saying “press any key to resume”.

2. Compute mean RT in the second block of practice. Call that X.

3. Present Instruction #2.

4. Present a practice block with 10 normal trials, 10 trials where you turn the background red (see below), and 10 more normal trials. RSI as in first 2 blocks but no feedback henceforth. At the end, show the subject their average response time on the red trials and their goal for that, along with average response time on the normal trials and total number of errors on normal trials. If they are going as fast as the goal (or within 50 msec of it) say “Good job – you kept the desired pace!”. If they are more than 50 msec too slow, say “Please try to speed up to reach the desired goal!”.

5. Repeat (4) three times.

6. Present 8 blocks of 80 trials as in (4). This is the “real experiment”. But here each block contains 5 sets of 4 red trials and 6 sets of 10 normal trials, in the following order:

10 normal trials

4 red trials

10 normal trials

.4 red trials

…

10 normal trials

Feedback is as in (4).

Instruction 1

Welcome to the experiment. We think you will find today’s experiment rather interesting. We are looking at how speed stress affects performance. In the first phase of this experiment, we would like you to get familiar with the task. A letter or digit (the character will be K, 7, P, or 3) will appear and you respond by pressing a button. Each character is mapped to a different response key labeled on the keyboard in that order from left to right: K, 7, P, 3. That’s it!

While you are performing the experiment, please keep the first two fingers of each hand rested on the four keys. Please try to respond as rapidly and accurately as possible. If you make a mistake, the computer will beep at you.

If you have any questions, please ask the experimenter. Otherwise, we can begin now. We will do two “blocks” of trials, each lasting less than two minutes.

Instruction 2

In the next phase of the experiment, the task will be the same. However, for certain periods within a block – when the computer screen turns red -- the computer wants you to respond extremely fast – much faster than you have been responding so far!

Your average response time during the previous block was X [show subject their actual time] milliseconds. (A millisecond is one-thousandth of a second.) When the red light goes on, we would like you to respond in no more than X-150 msec!

We understand that going this fast means you will make a lot of errors. When the red light goes off, you can go back to your normal mode of fast-but-accurate responding.

We’ll start by giving you a couple of very short practice blocks. Each of these will have 10 normal trials, 4 trials with the red light on (“red alert trials”), and 10 more normal trials. We’ll let you know how fast you were able to go after each block.

Instruction 3

In the next phase of the experiment, we are going to do 10 more blocks. Every block will cycle back and forth between 10 normal trials and 4 red alert trials.

Display on normal trials

Display on speeded trials

On red trials, the background turns red immediately after the previous response, and turns gray again after they make the next response.

Data Files

Rawfile contains

<Block #, Trial#, Stimulus, Response, RT, Correct/Incorrect, Red light on? [say Red vs. Normal]>

We will write specialized program to analyze the raw data file.