Conditioned reinforcement as a function of duration of stimulus.
Longer S+ time turns a simple cue into stronger conditioned reinforcement.
01Research in Context
What this study did
Parsons et al. (1981) asked a simple question. Does keeping the S+ signal on longer make it a stronger reward?
They used pigeons in a small chamber. Birds could peck a key to see the S+ for a short or long time.
Longer looks at S+ were the only pay-off. The team counted how hard the birds worked to get those looks.
What they found
Longer S+ time made the birds peck more. Short flashes did little.
The result fits a conditioned-reinforcement view: more exposure equals more value.
How this fits with other research
Foltin (1997) seems to disagree. Rats pressed less when running time, their reward, grew long. The clash clears up when you see the reward type. A et al. used a brief visual cue; W used minutes of wheel-running. Activity and conditioned stimuli follow different rules.
Edwards et al. (1970) backs the duration idea. A 120-second CS boosted lever pressing, while a 12-second CS cut it. Long signals can help or hurt, depending on what they predict.
Schmidt et al. (1969) added a hopper-light cue to mark long versus short feed times. The cue sharpened discrimination and gave the well-known peak shift. Marking duration helps animals notice the difference.
Why it matters
If you want a learner to stay engaged, stretch the good signal a little longer. In mand training, let the praise card or preferred video icon linger for a few extra seconds before fading. The longer S+ exposure can keep the child looking, asking, and learning without extra toys or candy.
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Extend your praise icon or light by two seconds and measure if observing responses increase.
02At a glance
03Original abstract
Pigeons were provided with three keys. Pecking the center key produced grain on a schedule that alternated at unpredictable times between a variable-interval component and extinction. On concurrent variable-interval schedules, pecking either side key produced a stimulus associated with the variable-interval component on the center key provided that said schedule was currently in effect. The independent variable was the length of time this stimulus remained on the keys. Pecking one side key produced the stimulus for 27 seconds, whereas the duration produced by pecking the other key varied for successive blocks of sessions. For the first four birds, the values tested were 3, 9, 27, and 81 seconds. For the second group, numbering three birds, the values tested were 1, 3, 9, and 27 seconds. The dependent variable was the proportion of total side key pecks that occurred on the variable key. For all birds, the function was positive in slope and negative in acceleration. This finding supports a formulation that ascribes the maintenance of observing responses in a normal setting to the fact that the subject exposes itself to the positive discriminative stimulus for a longer mean duration than it does to the negative stimulus.
Journal of the experimental analysis of behavior, 1981 · doi:10.1901/jeab.1981.36-41