Grace, R. C., Bragason, O., & McLean, A. P. (2003).
Rapid acquisition of preference in concurrent chains.
Journal of the Experimental Analysis of Behavior,
80, 235-252.
We report two experiments using a concurrent-chains procedure in
which one terminal-link schedule was fixed-interval 8 s and the
alternative schedule changed randomly from day to day. In
Experiment 1, the alternative schedule varied between 4 s and 16
s according to a pseudorandom binary sequence similar to the one
used by Hunter and Davison (1985). Similar to results with
concurrent schedules, pigeons' response allocation in the initial
link was most sensitive to the schedules arranged in the current
session, although some effect of prior history was evident.
Overall sensitivity was lower than for comparable data from
steady-state research. In Experiment 2, a unique value between 2
s and 32 s was used for the alternative-schedule delay in each
session. Sensitivity levels were similar to Experiment 1 and
remained unchanged across 61 sessions of training. For all
subjects, sensitivity was greater when the alternative-schedule
delay was greater than 8 s compared with when it was less than 8
s. Generalized-matching plots revealed evidence of clustering of
data points into two groups for some pigeons, suggesting that a
process similar to a categorical discrimination may have at least
partly determined response allocation. Overall, this research
shows that pigeons' initial-link response allocation can adjust
rapidly to frequent changes in the terminal links.
Key words: acquisition, preference, concurrent chains, key peck, pigeons