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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: J Abnorm Child Psychol. 2017 Jan;45(1):57–68. doi: 10.1007/s10802-016-0151-y

Figure 1.

Figure 1

Anatomy of a reaction time. After a stimulus is encoded, the decision process starts at z, and moves in the direction of one of two boundaries (is the stimulus a word or non-word? Should I go or not go?). Drift rate (v) is the rate at which information accumulates towards a decision. Once the decision process has reached one of the boundaries, the corresponding motor response is initiated. How far apart the boundaries are (i.e. the boundary separation, or a) is an indication of the conservativeness of the response criterion. Wider separations indicate more conservative responding (i.e. more information is needed before a decision can be reached). Non-decision time (Ter) represents the time it takes to complete all non-decision processes, such as stimulus encoding and motor preparation. Reaction time = Decision Time + Non-decision Time. Trial-to-trial variability in drift produces RT distributions.