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| International Paper Session - Behavioral Variability and Stereotypy |
| Sunday, May 25, 2008 |
| 4:00 PM–5:20 PM |
| Barbershop |
| Area: EAB |
| Chair: Lewis A. Bizo (Southern Cross University) |
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| Reinforced Behavioral Variability in Humans. |
| Domain: Basic Research |
| LEWIS A. BIZO (Southern Cross University), Kathleen Elizabeth Doolan (Southern Cross University) |
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| Abstract: The concurrent reinforcement of behavioral variability has previously been shown to facilitate learning of a specific target sequence in non-human animals (e.g., Neuringer et al., 2001), but attempts with human participants have produced contrary results (e.g., Maes & van der Goot, 2006). In a series of experiments human participants were required to produce a specific target sequence of responses. In three conditions positive feedback was always presented after production of the target sequence. Positive feedback was contingent on a variability criterion in one condition, was delivered according to a variable interval 60 s schedule in a second condition, and not delivered at all in another (the control condition). Participants in the control condition learned the target sequence faster than the other two groups; however, participants in the variability condition where more variable in the pattern of sequences they produced. The length of the target sequence differentially affected the learning of the target sequence for participants in the variability condition but not in the other conditions. The experiments are discussed in relation to the previously published accounts of human and animal studies of behavioral variability. |
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| Rats Respond at Higher Rates when Narrow Band of Response Durations is Reinforced. |
| Domain: Basic Research |
| JAMES KOPP (University of Texas, Arlington), Denise Lott Arellano (University of Texas, Arlington) |
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| Abstract: Leverpressing was reinforced in six rats during 30-minute sessions. An FR1 (baseline) schedule was in effect for the first 10 sessions. During the next 40 sessions, a differential reinforcement of response duration (DRRD) schedule selectively reinforced response durations between 600 and 700 ms. During the final 25 sessions, responses were reinforced in the same sequential order as the DRRD schedule, but without regard to duration (a yoked variable ratio reinforcement schedule). Interresponse time distributions were typically platykurtic during FR1 reinforcement. During the DRRD schedule, as response durations became differentiated, interresponse times became appreciably shorter and their distribution noticeably leptokurtic. During the Yoked VR schedule, interresponse time distributions tended toward platykurtosis once again. It is suggested that changes in response duration controlled by the DRRD schedule induced changes in the distribution of IRTs over and above those usually controlled by the temporal density and spacing of VR reinforcement per se. That is, all else being equal, VR reinforcement during response differentiation may control response rates different from rates controlled by VR reinforcement alone. |
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| Behavioral Correlates of Equine Stereotypy Phenotype. |
| Domain: Basic Research |
| MATTHEW PARKER (University of Southampton), Edward Redhead (University of Southampton), Deborah Goodwin (University of Southampton ), Sebastian McBride (Royal Agricultural College) |
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| Abstract: Horses that display stereotypic (repetitive, idiosyncratic and invariant response patterns) behavior have been shown to have differences in central nervous system physiology. Specifically, they have been found to have sensitized striatal dopaminergic pathways. Pharmacological sensitization of the striatum has been shown to lead to an accelerated shift from planned behaviour (response-outcome) to habital responding (stimulus-response), in the context of US devaluation and place-response paradigms. Therefore, theoretically, endogenously produced sensitization would be expected to lead to a similar accelerated shift. In the present study, matched pairs of stereotypic and non-stereotypic horses were trained to locate food in a standard cross-maze. After training, subjects were challenged with a probe trial, in which they were placed in an immediately adjacent mirror image maze. Stereotypic subjects were found to develop habitual responding (i.e., adopt a motor response strategy) at a faster rate than non-stereotypic counterparts. Results are discussed in the context of the equine stereotypy phenotype. |
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