Home > Psychology > SDT Simulation

RippleSoft

Instructional Software for
Statistics & Experimental Psychology

RippleSoft Software
www.ripplestat.com
ripplesoftware@mac.com

Signal Detection Theory Simulation

Signal Detection Theory: Simulation

Click here to open page with full-sized images

SDT Simulation: The data collection task

Data Collection

This is the card the subject sees for making judgments of whether the stimulus object is "Noise Only" or "Signal + Noise."

Nine trials have been completed. The user must decide whether the black rectangle indicating the "Dgree of Evidence" a stimulus occurred represents "Noise Only" or "Noise + Signal". Most stimulus locations can be produced by either of the conditions.

Also revealed are the settable parameters of the simuluation and the data archive of the completed trials.

SDT Simulation: The data collection task

Available Help and Instruction

Clicking on the "Info" button displays a stack containing instructions, directions, and explanation.

The stimulation is a computerized version of a task developed by Dr. Henry Cross.

The experimenter has three dice (two "green" and one "red") The green dice are standard dice. The red die has three sides that are blank and three sides that have 3 pips. When the three die are thrown, if the red die comes up blank it is a "Noise Only" trial. When the red die comes to rest with pips on top it is a "Noise + Signal" trial. The degree of evidence is the total of the tops of the three dice.


SDT Simulation: The data analysis display

Data Analysis

After completing the judgment trials, the student, presses the "Process" button to have have the results categorized into the number of correct detections, false alarms, correct rejections, and misses. The software plots the results and calculates the proportion of correct detections and false alarms.

SDT Simulation: Calculate Measures of Sensitivity and Response Bias

Data Analysis

Clicking on the "Calc" button displays a calculation tool that allows the student to determine the values for response bias and sensitivity from either frequencies or the proportions of correct detections and false alarms.

The picture illustrates the results of the calculation based on frequencies.

SDT Simulation: The data analysis displaying 9,437 Trials

Data Analysis

The judgment task can be automated by choosing a particular degree of "evidence" for deciding the trial represents the "Noise + Signal" stimulus event.

These results are based on almost 5,000 judgments.

SDT Simulation: Video of Several Automated Trials

Data Analysis

The judgment task can be automated by choosing a particular degree of "evidence" for deciding the trial stimulus represents the "Noise + Signal" event.

In this video the criterion is set to be a value of 10.

After each response the subject is given feedback.



© 2005 by Burrton Woodruff. All Rights Reserved. Modified Thu, Dec 20, 2007s