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Experiment Author: Psychology Software Tools, Inc.
The Chronos Adapter for BIOPAC STP100C sample experiment illustrates how to use Task Events to send markers from the E-Prime experiment to the STP100C digital interface.
The sample experiment presents a Visual Oddball Task: each trial presents the letter "O" or "X" and the participant's task is to distinguish between these letters. 80% of the trials present the letter "O" and 20% of the trials present the letter "X". The experiment sends the marker value 1 when the letter "O" is shown and the value 128 when the letter "X" is shown.
The Chronos Adapter for BIOPAC STP100C provides access to 8 digital outputs (from Chronos to the BIOPAC digital interface and four digital inputs (from the BIOPAC digital interface to Chronos) as shown below:
This sample experiment illustrates the digital output functionality. When Chronos sends a marker on its first digital output, the STP100C receives it on Digital Input #8 (pin 2). When Chronos sends a marker on its eighth digital output, the STP100C receives it on digital input #15 (pin 9). To determine which STP100C digital input receives a trigger value sent from Chronos, do the following:
- Represent the integer marker being sent as a binary number.
- Map the binary number to Chronos's digital outputs to determine which outputs are set high (set to 1).
- Examine which STP100C digital inputs map to the Chronos digital outputs that are set high.
For example, the sample sends the integer value 1 when the stimulus = the letter "O":
- Integer value 1 equals the binary number 0000 0001 (Least Significant Bit is right-most bit).
- 0000 0001 sets the first Chronos digital output high; all other digital outputs are low.
- As shown in the table above, the first Chronos Digital Output maps to STP100C Digital Input 8.
The sample sends the integer value 128 when the stimulus = the letter "X":
- Integer value 128 equals the binary number 1000 0000.
- 1000 0000 sets the eighth Chronos digital output high; all other digital outputs are low.
- The eighth Chronos Digital Output maps to STP100C Digital Input 15.
NOTE: To configure the E-Prime experiment to receive signals sent from the STP100C to one of the Chronos adapter's four digital inputs, create an InputMask for the Chronos device that looks for the pseudo button responses 7, 8, 9, and/or A, which map to Chronos digital inputs 7, 8, 9, and 10. See Section 6.2 Pseudo Buttons of the Chronos Operator Manual and DEVICE: How To: Synchronize E-Prime with an incoming marker/press via an Input Mask for details.
NOTE: Extract all the files in the attached .zip file to the same folder. The sample experiment displays images that must be located in the same folder as the experiment.