Effects of D-amphetamine and ethanol on variable and repetitive key-peck sequences in pigeons.
Amphetamine and ethanol each wreck pigeon sequence accuracy in their own way, warning us that drugs can masquerade as learning problems.
01Research in Context
What this study did
Scientists gave pigeons a repeating four-peck sequence on two keys. Birds earned food for copying the pattern exactly.
On other trials they had to vary the order. The team then gave d-amphetamine or ethanol and watched what broke.
What they found
Both drugs made exact repeats sloppy. Amphetamine also cut total pecks. Ethanol left peck count alone but still wrecked accuracy.
The drugs hurt repeat and vary rules in different ways, showing they attack different control points.
How this fits with other research
McIntyre et al. (2002) saw amphetamine slow fast pecks and speed slow ones. Gadow et al. (2006) now show the drug also scrambles the order inside a string, not just the rate.
Davison (1969) found amphetamine can wipe out key pecking completely. The new data narrow the loss to within-sequence control, a finer grain of the same story.
Locurto et al. (1980) showed high ratio strain can flip stimulant harm into help. Here, discrete sequences had no ratio pressure, so only disruption appeared, tying the papers together.
Why it matters
If you run multiple-step tasks with clients, know that outside factors like medication can mimic skill loss. Check accuracy on each step, not just total responses. When errors rise after a med change, break the chain into smaller parts and retrain each piece before blending them back together.
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02At a glance
03Original abstract
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 keypeck 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.
Journal of the experimental analysis of behavior, 2006 · doi:10.1901/jeab.2006.17-06