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Choice Relations and Environmental
Stability
William M. Baum,
Department of Psychology, University of New Hampshire, USA
According to evolutionary theory,
natural selection depends on environmental stability.
If a feature of the environment changes rarely, phenotypic patterns
adapted to that feature tend to become fixed in a population.
If the environmental feature changes frequently, selection results
in simpler responses to the fluctuation. Intermediate levels
of change result in intermediate adaptations or compromises between
the two possible extremes. If reinforcement resembles natural
selection, environmental stability ought to affect behavioral
patterns in a parallel way. Results of experiments on concurrent
performance at the extremes of environmental stability support
this parallel. When reinforcer ratios change rarely, a behavioral
pattern including both alternatives ("fix and sample")
emerges. When reinforcer ratios change frequently, a simple pattern
of reinforcement tracking occurs instead. Intermediate frequencies
of changing reinforcer ratios appear to select intermediate performances.
These analyses support the parallel between reinforcement and
natural selection.
Key words: choice, concurrent
schedules, natural selection, reinforcement,
environmental stability |