Abstract:
Timing Without a Timer
Interval timing in operant conditioning is the covariation of a temporal
dependent
measure such as wait time with a temporal independent variable such as
fixed-interval duration. The major theories of interval timing, scalar
expectancy theory (SET: Gibbon, 1977; Church, Meck & Gibbon, 1994) and
the behavioral theory of timing (BeT: Killeen & Fetterman, 1988; Killeen,
1991), incorporate an internal clock (or "pacemaker"), a theoretical
concept with surprisingly little behavioral or physiological support.
We propose an alternative, pacemaker-free view according to which timing
emerges from the competition between the reinforced (terminal) behavior
and all the other (elicited, interim) behaviors, a process whose strength
is controlled by the recent memory for reinforcement. The model explains
(1) how animals learn to space successive responses in time when only
interresponse times longer than a given value are reinforced (spaced
responding), (2) how animals on fixed-interval (FI) schedules learn to
wait for a fixed fraction of the prevailing interreinforcement intervalx,
(proportional timing), and (3) why the ratio between standard deviation
and mean wait time is approximately constant (Weber's law).
Submitted to: Psychological Review
Address correspondence to Valentin Dragoi.
Last Updated: 06-Jan-99