Interstimulus interval effects on habituation: A systematic review with theoretical implications.

After more than a century of research across a broad phylogenetic spectrum, the prevailing belief among experimental psychologists is that response diminution due to iterated stimulation or habituation depends on the interval at which the stimulus is repeated, known as the interstimulus interval (ISI). Moreover, there is some consensus on the somewhat paradoxical fact that although this interval is inversely related to the ongoing decrement in responding, it is directly related to the persistence of the decrement. This fact has been taken as a probe of two functional processes: a short-term process favored by short ISIs and a long-term process favored by longer ISIs. Neurobiological data, mainly from invertebrates, tend to support this view. This literature review examines the extensive behavioral literature on this topic, with particular attention to the experimental designs employed. The most common design used to assess ISI effects on habituation tracks changes in responding over repeated trials (the "habituation curve"), but this method faces interpretative challenges, particularly the conflation of learning with performance and of short-term with long-term effects. Some of these issues have been addressed by studies of "refractory-like" effects, which are often found to vary inversely with the ISI. A few of these studies report stimulus specificity and dishabituation, suggesting that these brief effects may reflect genuine short-term learning. Numerous studies using retention tests also suggest that longer ISIs are more effective in producing longer lasting learning. These two approaches offer complementary insights into the timing of habituation. Nonetheless, further studies using integrated designs within a single animal model and guided by theoretical frameworks are still needed. Two theories of habituation are discussed, along with recommendations for future research. (PsycInfo Database Record (c) 2026 APA, all rights reserved).