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SSRTcalc (version 2.1.1)

fixed: Fixed-SSD stop-signal task data (motion discrimination)

Description

A long-format dataset from a stop-signal variant of a random-dot motion-discrimination task in which the stop-signal delay (SOA) was set to one of six fixed values rather than being tracked by a staircase. It complements the adaptive dataset and is intended for demonstrating the fixed-SSD estimators integration_fixedSSD and mean_fixedSSD.

Usage

fixed

Arguments

Format

A data frame with 28,799 rows (50 subjects) and 8 columns:

SubjID

Integer subject identifier. Subject 2 from the original recording is excluded (see Details), so the IDs run 1 and 3-51.

trial

Trial number within subject (1-576; a subject with one removed trial has 575).

vol

Trial type: 0 = go trial, 1 = stop trial.

RT_exp

Observed reaction time in milliseconds. NA when no response was made (successfully inhibited stop trials and go-trial omissions).

correct

Accuracy indicator (1 = correct go response or successful inhibition; 0 otherwise).

soa

Stop-signal delay (SOA) in milliseconds for stop trials, one of six fixed values (100, 200, 300, 400, 500, 600 ms); NA on go trials, matching the adaptive dataset.

coh

Motion coherence for the go discrimination (0.1, 0.5, or 0.8), an experimental difficulty manipulation.

response

Response direction ("left", "right", or NA when no response was made).

Details

All timing variables are in milliseconds, matching the rest of the package and the adaptive dataset.

During preparation, subject 2 (who had no recorded responses on any trial) and a single stop trial with a recorded reaction time of 0 ms were removed. Subject identifiers otherwise follow the original recording, so identifier 2 is absent.

Examples

Run this code
data(fixed)
d <- fixed[fixed$SubjID == 1, ]
integration_fixedSSD(d)
mean_fixedSSD(d)

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