Experiment Duration_Pilot2

 

BASIC DESIGN.

 

Subjects will hear tones lasting between 700 milliseconds and 850 milliseconds, and attempt to judge their duration.  In this study, we simply want to see what the learning curve looks like as subjects perform this task for about an hour.  The previous study surprisingly yielded no perceivable learning, something which the reduced number of categories in this experiment will hopefully counter.  We will run about 6 people and see if they show a steady improvement in the task.

 

Instructions.

 

In this study you are going to be trained in a rather peculiar task that you may find interesting, and which may possibly even be useful to you some day. You are going to be estimating the duration of brief intervals. You will hear tones lasting for a randomly chosen period of time ranging between 700 milliseconds and 850 milliseconds (varying in units of 50 milliseconds), and then you will try to estimate how long the tone lasted. To do that, you will use the mouse to click how long you think the interval was.

There will be buttons arranged along the bottom of the screen: push the left-most buttons for shorter durations, and push the right-most buttons when you hear longer durations. You will receive feedback after every response telling you the correct answer (an asterisk will appear above the correct button). The experiment will be divided into 12 blocks of trials, each lasting just a few minutes. Most people find this task rather challenging and at least somewhat interesting, and we hope you do as well.

 

Design:  12 blocks X 36 trials per block.

Experimental Variables: No independent variables.  Duration is randomly selected on each trial in increments of 50 msec.

 

Procedure for an individual trial:

 

1. randomly select an integer x ranging between 0 and 3 (inclusive).

 

2. present plus sign as warning for ½ second, then take that away, then play a 800 hz tone lasting for  (x*50)+700 msec.  (using 4 .wav files)

 

3. subject guesses the duration by clicking on one of 4 unlabeled buttons

  

4. Provide feedback, giving the person 1.6 seconds to "digest" it.  Then pause 1.5 seconds, and go on to next trial.

 

DATA STORAGE

 

On each trial, the program writes out to the disk

<Block #; Trial #; Actual Duration; Subject's Estimate of Duration>

 

I guess that's it for the raw data file.

 

Also please print out a summary data file with 12 rows, containing the following columns:

 

1. Block #

 

2. Average of the absolute values of the difference between the actual duration and the subject’s estimate of the duration across trials within the block. (so if one trial the subject overestimates by 100, and on another trial the subject underestimates by 100, the errors do not cancel out, and the average difference = 100.)

 

3. Average difference between the actual duration and the subject's estimate of the duration.  (so if one trial the subject overestimates by 100, and on another trial the subject underestimates by 100, the errors cancel out and the average difference = zero.)

 

4. Average squared difference between the actual duration and the subject's estimate of the duration.  (so if one trial the subject overestimates by 100, and on another trial the subject underestimates by 100, the average squared difference = 10,000.)

 

[these are 3 widely used measures of precision.]