Ward, R.D., Bailey, E.M., & Odum, A.L. (2006).
Effects of d-amphetamine and ethanol on variable and repetitive
key-peck sequences in pigeons.
Journal of the Experimental Analysis of Behavior, 86, 285-305.
This experiment assessed the effects of d-amphetamine and ethanol on
reinforced variable and repetitive key-peck sequences in pigeons.
Pigeons responded on two keys under a multiple schedule of Repeat and
Vary components. In the Repeat component, completion of a target sequence
of right, right, left, left resulted in food. In the Vary component, 4-peck
sequences differing from the previous 10 produced food. d-Amphetamine
(0.1-3.0 mg/kg, i.m.) was administered in two separate phases, separated
by ethanol administration (1.0-2.0 g/kg, i.g.). Under control conditions,
measures of variability were high in the Vary component, and lower in the
Repeat component. Following administration of the highest dose of d-amphetamine,
but not ethanol, response rates decreased in both components. d-Amphetamine and
ethanol tended to increase overall sequence variability in the Repeat component,
and had less of an effect in the Vary component. Performance in the Repeat
component during Phase 2 of d-amphetamine administration was more disrupted than during Phase 1.
Measures of variability and repetition based on shifts in the relative
frequency distributions of the 16 possible key-peck sequences differed
from those based on the overall measure of variability, highlighting the
importance of considering both molar and molecular measures when assessing
the effects of drugs on reinforced variability and repetition. In addition,
the shifts in the relative frequency distribution of response sequences
suggest that d-amphetamine produced decrements in repeat performance
by decreasing discriminative control within response sequences, whereas
ethanol decreased repeat performance by decreasing discriminability between
components as well as discriminative control within response sequences.
Key words: behavioral variability, repetition, response sequences, stereotypy,
d-amphetamine, ethanol, key peck, pigeons