Overshadowing by fixed- and variable-duration stimuli

• Published in: Quarterly journal of experimental psychology (2006) Vol. 68; no. 3; pp. 523 - 542
• Main Authors: Bonardi, Charlotte, Mondragón, Esther, Brilot, Ben, Jennings, Dómhnall J.
• Format: Journal Article
• Language: English
• Published: London, England Routledge 04.03.2015; SAGE Publications
• Subjects: Acoustic Stimulation; Animals; Association Learning - physiology; Associative learning; Conditioning, Classical; Cues; Discrimination, Psychological; Inhibition, Psychological; Male; Overshadowing; Photic Stimulation; Psychological Theory; Rats; Rats, Long-Evans; Stimulus distribution form; Time Factors; Time Perception - physiology; Timing; Rats; Associative learning; Stimulus distribution form; Overshadowing; Timing
• ISSN: 1747-0218; 1747-0226
• DOI: 10.1080/17470218.2014.960875

Two experiments investigated the effect of the temporal distribution form of a stimulus on its ability to produce an overshadowing effect. The overshadowing stimuli were either of the same duration on every trial, or of a variable duration drawn from an exponential distribution with the same mean duration as that of the fixed stimulus. Both experiments provided evidence that a variable-duration stimulus was less effective than a fixed-duration cue at overshadowing conditioning to a target conditioned stimulus (CS); moreover, this effect was independent of whether the overshadowed CS was fixed or variable. The findings presented here are consistent with the idea that the strength of the association between CS and unconditioned stimulus (US) is, in part, determined by the temporal distribution form of the CS. These results are discussed in terms of time-accumulation and trial-based theories of conditioning and timing.