Interstimulus interval

In experimental psychology, the interstimulus interval (abbreviated ISI ) is the time interval between the occurrence of two stimuli , i.e. the time from the end (offset) of a first stimulus to the beginning (onset) of a subsequent stimulus. In contrast, the onset asynchrony (SOA) stimulus describes the time span between the start of the first and the following stimulus. If the duration of the first stimulus is denoted, then: ${\ displaystyle D}$

{\ displaystyle ISI = SOA-D}

These variables play a special role in experiments on movement perception, as they were first carried out on a large scale by Max Wertheimer in 1912. Two visual stimuli are presented to a test person alternately, first on the left and then on the right. Depending on these variables, the test subjects perceive different phenomena, in particular the beta movement or the phi phenomenon . The interstimulus interval can also be negative. This means that the presentation times of the two successive stimuli overlap.

The interstimulus interval has a special meaning in learning psychology . When acquiring a conditioned reflex , this is how the time interval between the end of the conditioned stimulus and the beginning of the unconditioned stimulus is called.

Individual evidence

↑ ^a ^b Christina Bermeitinger, Wilhelm Glaser: Interstimulusintervall (ISI). In: Hogrefe Verlag, Bern. Dorsch, Lexicon of Psychology, accessed April 25, 2019 .
↑ ^a ^b Vebjørn Ekroll, Franz Faul, Jürgen Golz: Classification of apparent motion percepts based on temporal factors. In: Journal of Vision. Volume 8, 2008, No. 31, pp. 1-22 ( online ).

[Dorsch-1] Christina Bermeitinger, Wilhelm Glaser: Interstimulusintervall (ISI). In: Hogrefe Verlag, Bern. Dorsch, Lexicon of Psychology, accessed April 25, 2019 .

[Ekroll2008-2] Vebjørn Ekroll, Franz Faul, Jürgen Golz: Classification of apparent motion percepts based on temporal factors. In: Journal of Vision. Volume 8, 2008, No. 31, pp. 1-22 ( online ).