Some temporal properties of behavioral contrast.
Behavioral contrast can surge within minutes and stick around even after the pay-off returns.
01Research in Context
What this study did
Pigeons pecked two keys. One key always paid off. The other key sometimes paid off and sometimes did not.
The experimenter switched the pay-off rule many times each session. He watched how fast the birds pecked the key that still paid.
What they found
When the second key stopped paying, pecking on the first key jumped up right away.
The jump stayed even after the second key started paying again. Contrast can begin fast and outlast the change.
How this fits with other research
REYNOLDS et al. (1961) saw the same jump six years earlier. They used slower pay schedules, so the effect was already known to work with different timings.
Dews (1978) later showed the jump can come from simple stimulus-reward links, not only from the pay rule. His data add a Pavlovian layer to the operant story.
Parsons et al. (1981) looked picky. They said contrast only shows up if you remove accidental rewards. Their warning means you must run clean sessions or you might miss the effect.
Why it matters
Your client’s problem behavior can spike the moment a second task gets harder or stops paying off. The spike may linger even after you make the second task easy again. Watch the first task closely after any schedule change, and wait before you judge whether the intervention really worked.
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02At a glance
03Original abstract
Pigeons were rewarded on a variable time interval for pecking a translucent key illuminated with either a 45 degrees or a vertical line. The key illumination changed every 2 min during daily 1-hr sessions. When the rates of pecking were stable, reinforcement was omitted in the presence of the 45 degrees line. Responding in the presence of the vertical line increased. This increase did not disappear when responses to the 45 degrees line were once more reinforced, but when reinforcements for responses in the presence of the 45 degrees line were again omitted, responding to the vertical line increased again. After the second alternation of these two procedures, the increased responding to the vertical line appeared when responses were not reinforced in the presence of the 45 degrees line, and disappeared when reinforcement was available during both stimuli. In a second experiment, the key illumination changed between sessions only, so that 1-hr sessions of reinforcement and non-reinforcement occurred on alternate days. Responding to the vertical line still increased when responding to the 45 degrees line was not reinforced, but the increase tended to disappear during the session.
Journal of the experimental analysis of behavior, 1967 · doi:10.1901/jeab.1967.10-159