Sequences of spaced responses: Behavioral units and the role of contiguity.
Spaced response sequences can act like single units under the matching law, but the boundary is fuzzy.
01Research in Context
What this study did
Jones et al. (1992) asked pigeons to peck a key in spaced-out runs. The birds had to wait a few seconds between pecks to earn food.
The team then looked at whether the whole run, not just single pecks, acted like one big response. They checked if the matching law still worked for these long, spaced sequences.
What they found
The pigeons’ time and pecks followed the matching law, but only partly. Long runs earned more food, yet the fit was messy.
Some birds seemed to treat the whole run as one unit. Others still acted peck by peck. No clear line showed when a run becomes a unit.
How this fits with other research
Lejuez et al. (2001) got a cleaner match. Rats chose between two wheels under the same law. Their running time tracked reinforcement rate almost perfectly. The messy fit in M et al. may come from using long pauses inside each sequence.
Angle (1970) showed that reinforcement must follow the prior response for pauses to link together. M et al. built on this idea by asking if whole strings of pauses can be reinforced as one chunk.
James et al. (1981) proved that even electric shock can hold a sequence together. Food or shock, the schedule, not the reinforcer type, seems to create the unit.
Why it matters
When you shape long chains of behavior, decide if you want each step or the whole chain to count. If the pauses are part of the skill, reinforce right after the final step to glue the chain together. If you reinforce too early, the learner may treat each step as separate. Watch for partial matching: more reinforcement should pull more time into the chain, but the link may stay loose.
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02At a glance
03Original abstract
Sequences of temporally spaced responses were reinforced to investigate the effects of delay of reinforcement on the formation of functional behavioral units. In Experiment 1, rats' two- and three-response demarcated sequences of left and right lever presses were reinforced such that different response distributions would occur depending on whether the sequences themselves or individual responses were functional units. The matching law could thus be obeyed either by individual responses or by sequences, but not by both; intermediate results were possible. Both regular (nonretractable) and retractable levers were used; the retractable levers precluded the occurrence of insufficiently spaced responses. At a minimum interresponse time of 5 s for regular levers and 7 s for retractable ones, matching results were intermediate, with greater evidence of sequence conditionability in the two-response sequences than in the three-response sequences. In Experiment 2, the required minimum interresponse spacing for two-response retractable-lever sequences was varied in an attempt to locate the sequence matching threshold. This attempt was unsuccessful, but the sequences (instead of individual responses) more closely obeyed the matching law. In the shortest spaced condition, conditional probability data on Lag 1 sequence emission order showed marked, highly similar patterning for all rats, indicating sequential control of the sequences. Post hoc definition of the behavioral unit in these studies is ambiguous. Although reinforcement contiguity was important, aspects of the results could support both molar- and molecular-level interpretations.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.58-537