Estimating Stop Signal Reaction Times and Stop Signal Delay

Helper functions for estimating the SSRT (stop signal reaction time) in a Stop-Signal Task based on Verbruggen et al. (2019) and a mid-run estimates method for computing the mean SSD (stop signal delay) based on Levitt (1971) .

SSRT Calculation

SSRTs can either be calculated:

• Using a Mean estimation (M_RT - M_SSD)
• Utilising the RT distribution of correct Go Trials to estimate the Stop-Signal Reaction Time.

Since the 2nd approach uses an integrative procedure that estimates the SSRT from the RT distribution using p(response | signal); in cases where p(response | signal) == 50%, both estimates should produce identical results.

(see Verbruggen et al. 2019)

SSD Calculation

The Stop Signal Delay can be calculated as either the mean Value of all SSDs, or, more robustly, using the mid-run estimates method which is more suited to Staircase paradigms. This method computes the mean value by averaging the midpoints of every second run (see Levitt, 1970).

Installation

pak::pak("sonntasa/sstFun")