The psychological distance to reward.
Extra steps in a reinforcement schedule make the reward feel farther away, even when the wait time stays the same.
01Research in Context
What this study did
Scientists gave pigeons two keys. Pecking one key led to a simple fixed-interval schedule. Pecking the other key led to a chained fixed-interval schedule. Both keys delivered food after the same total wait time.
The birds could switch keys at any moment. The team recorded which key each pigeon chose most often.
What they found
Every pigeon preferred the simple schedule. The longer the final link of the chain, the stronger the preference grew.
Adding extra chain links made the reward feel farther away, even though the actual delay stayed the same.
How this fits with other research
Wacker et al. (1985) ran the same setup and got the same result — a direct replication.
Reed et al. (1988) later showed that breaking the schedule into more segments makes the dislike even stronger.
Henton (1972) looked like a contradiction: pigeons were indifferent between chained and tandem schedules. The difference is W compared chained to tandem, not chained to simple. Tandem still has segments, so the reward still feels distant.
Why it matters
For your clients, keep reinforcement schedules short and unbroken. Token boards with many steps can feel like chained schedules and lose value. Try fewer tokens or shorter intervals. Deliver the backup reinforcer as soon as the target behavior happens. Simple schedules keep motivation high.
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02At a glance
03Original abstract
Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced entry into one of two different and mutually exclusive terminal link stimuli according to identical but independent variable-interval schedules. In one experiment, a two-component chained fixed-interval schedule produced food in one terminal link while a simple fixed-interval schedule produced food in the other terminal link. When the interreinforcement intervals were equal in the two terminal links (i.e., the simple fixed-interval was twice the size of each of the components in the chained schedule) pigeons preferred the simple fixed-interval as measured by their relative rates of responding in the concurrently available initial links. This preference increased as the duration of the terminal links increased. The preference could be reversed by making the simple fixed-interval schedule sufficiently longer than the chained schedule. In the second experiment, the terminal links consisted of two- vs three-component chained fixed-intervals, again with equal interreinforcement intervals. Pigeons preferred the two-component chain to the three-component chain, although these results were less consistent and less dramatic than those in the first experiment. Again, preference increased as the duration of the terminal links increased. The results show that an organism's choice for a schedule will be substantially lowered by the chaining operation even when the interreinforcement interval remains constant.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.18-23