Fixed step staircase objects

An object of type fixedStepStaircase is an “n-down/m-up” (i.e. n correct responses → step harder, m incorrect responses → step easier) staircase with fixed step sizes. Subject threshold is calculated as the average staircase value across reversals. In an experiment script you can make a fixedStepStaircase object outside trials with the command fixedStepStaircaseObject and add it with addToExperiment.

Input properties


No default

Initial staircase value (a number).


Default: step on 2 correct / 1 incorrect responses in a row

A 1×2 vector setting how many [correct incorrect] response trials in a row are needed to step the staircase value in the respective direction. e.g. <cd>[2 1]<cd> gives a 2-harder/1-easier staircase.​


No default

A 1×2 vector setting staircase value step sizes for [correct incorrect]. One number must be positive (increase staircase value), the other negative (decrease). Which one you make positive or negative depends on whether it’s an increasing or decreasing psychometric function.


Default: numFastReversals = no fast reversals
Default: fastStepSizes = stepSizes above

You can set a fixed step staircase so that for the first few reversals it steps on every response and maybe takes larger steps in order to get close to the subject’s threshold fast. These “fast reversals” count toward numReversals and maxNumReversals but not threshold.

numFastReversals is number of reversals to do fast. 0 = none.

fastStepSizes is like stepSizes above. <cd>[]<cd> = same as stepSizes.

Input properties all objects have


Record properties

PsychBench uses record properties to record information during experiments. You can't set record properties but you can see them in experiment results using input property report.