PSY 321:  Cognitive Processes
Concept Formation

This experiment consists of a training session and a testing session.  In the training session you will see a pattern of nine dots.  Each pattern is a member of one of three different categories.  You are to indicate which category each pattern belongs to by pressing either the 1, 2, or 3 key.  Respond as accurately as possible, but within that constraint, as quickly as possible.  After responding, you will be given feedback for 2 seconds about whether you were correct or not, and to which category the pattern belongs.  After the feedback, the process (see a pattern, categorize the pattern) will repeat.  Initially your responses will be random, but by carefully paying attention to the feedback, you will soon learn to which category each pattern belongs.  The training session continues until you become sufficiently accurate at the task to categorize each pattern correctly twice in a row.  During training, there are 12 patterns -- four patterns for each of the three categories.

The testing session begins immediately after the end of training (you may not even know that you have entered the testing session.)  The only difference between the testing and training sessions is the patterns that are used.  During testing, each of the three categories will have seven patterns -- one of the seven patterns will be the prototype from which all of the other patterns were created (the prototype), two of the seven patterns will be patterns from the training session (old instances), two of the seven patterns will be new patterns generated from the prototype according to the same rule as the training patterns (new instances, high variability), and two of the seven patterns will be new patterns generated from the prototype but will be more similar to the prototype than the training patterns (new instances, low variability).  For each pattern that is presented, indicate the category to which you think it belongs by pressing either the 1, 2, or 3 key as accurately as possible, and within that constraint, as quickly as possible.  Each of the 21 patterns (seven pattern per category) will be presented twice.

Once you have finished the testing session, your reaction times (in milliseconds) and proportion correct for each of the four types of testing patterns (prototype, old, new with high variability, and new with low variability) will be displayed.  You should then submit your data to the web server so that it can be stored with the rest of the data from your classmates.