Landon, J., Davison, M., & Elliffe, D. (2003).
Choice in a variable environment: Effects of unequal reinforcer distributions.
Journal of the Experimental Analysis of Behavior,
80, 187-204.
Six pigeons were trained in a procedure in which sessions
included seven unsignaled components, each offering two pecking
keys, and each providing a potentially different reinforcer ratio
between the two keys. Across conditions, various combinations of
reinforcer ratios and reinforcer-magnitude ratios were used to
create unequal reinforcer distributions between the two
alternatives when averaged across a session. The results extended
previous research using the same basic procedure that had
included only reinforcer distributions symmetrical around 1:1.
Data analyses suggested that the variables controlling choice
operated at a number of levels: First, individual reinforcers had
local effects on choice; second, sequences of successive
reinforcers obtained at the same alternative (continuations) had
cumulative effects; and, third, when these sequences themselves
occurred with greater frequency, their effects further cumulated.
A reinforcer obtained at the other alternative following a
sequence of continuations (a discontinuation) had a large effect
and apparently reset choice to levels approximating the sessional
reinforcer ratio.
Key words: concurrent schedules, choice, reinforcer-ratio variation,
reinforcer sequences, generalized matching, key peck, pigeon