Cerutti, D., & Catania, A. C. (1997).
Pigeons' preference for free choice: Number of keys versus key area.
Journal of the Experimental Analysis of Behavior,
68, 349-356.
In concurrent-chains schedules, pigeons prefer terminal links
that provide two keys correlated with reinforcers (free choice)
over those that provide only one key (forced choice),
terminal-link reinforcement rates being equal. With same-size
keys, free choice provides a larger area available for pecking.
Preferences were examined using terminal links that differed in
key number only (one or two) or key size only (small and medium
or medium and large), or that equated the area of the two
free-choice keys with that of the forced-choice key. Medium
(standard) keys were typically preferred to small keys, but
indifference was typically obtained between medium and large
keys. The size preference usually overrode free-choice preference
with one medium key pitted against two small keys, but
free-choice preference was reliably observed with one large key
pitted against two medium keys. In other words, preferences were
a joint function of key number and key area, implying that
free-choice preference is not reducible to preference for larger
key areas. Free-choice preference requires separate keys rather
than larger areas; the relevant behavioral units are the
discriminated operants correlated with each terminal-link key
rather than classes defined by topographical features such as
area or perimeter.
Key words: concurrent-chains schedules, free and forced choice,
preference, key number, key area, key peck, pigeons