Effects of relative reinforcer frequency on complex color detection.
Reinforcer frequency and stimulus clarity each steer choice alone, so you can adjust one while holding the other steady.
01Research in Context
What this study did
Researchers set up a pigeon lab with three colored keys.
Birds earned grain for pecking the key that matched a sample color.
The team changed how often each color paid off while keeping the hues easy or hard to tell apart.
They wanted to see if payoff odds and color clarity work together or alone.
What they found
Pigeons split their pecks to match the exact payoff odds.
When colors looked similar, accuracy dropped but the payoff split stayed true.
No hidden bias showed up; frequency and clarity acted like two separate dials.
How this fits with other research
Skrtic et al. (1982) already showed choice beats rate for tracking reinforcer odds.
The 1989 study keeps that rule and adds color discriminability as a second, independent knob.
Iwata (1993) later asked if birds care about overall scheduled odds or just the ones they actually get.
Both papers use concurrent schedules, but Iwata (1993) switches between single and together trials to test the molar view the 1989 model assumes.
The results line up: molar scheduled rates drive choice when alternatives sit side-by-side.
Why it matters
If you run concurrent teaching programs, treat reinforcer odds and task clarity as two levers.
Boost one without touching the other if you want a clean, predictable shift in student time-on-task.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Keep the same reinforcer rate for two tasks, make one task slightly harder to see, and check if time allocation stays equal.
02At a glance
03Original abstract
Pigeons were trained under a discrete-trials detection procedure in which one of a set of color stimuli was presented on the center key and a single response turned off the stimulus and illuminated two side keys. Single responses to one or the other side key produced occasional reinforcers depending on the value of the color stimulus. In Experiment 1, one color-stimulus set comprised 559, 564, 569, and 574 nm, and right-key pecks were occasionally reinforced following presentations of members of this set. The other stimulus set comprised 579, 584, 589, and 594 nm, and left-key pecks were occasionally reinforced following presentations of members of this set. Across seven experimental conditions, the left/(left + right) relative reinforcer frequency was varied from .1 to .9. In Experiment 2, one stimulus set contained only one member, 574 nm, and right-key responses were occasionally reinforced following its presentation. Over 12 experimental conditions, two manipulations were carried out. First, the number of stimuli comprising the other stimulus set was increased from one (579 nm) to two (579 and 584 nm) to three (579, 584, and 589 nm) and to four (579, 584, 589, and 594 nm), and left-key responses were reinforced occasionally following center-key presentations of members of this set. Second, for each stimulus combination, the left/(left + right) relative reinforcer frequency was varied from .1 to .5 to .9 across three experimental conditions. The principal finding of Experiments 1 and 2 was that reinforcers and stimuli interacted in their effects on behavior. In Experiment 3, pairs of adjacent stimuli (5 nm apart) in the range 559 to 594 nm were presented in each experimental condition, and the left/(left + right) relative reinforcer frequency was held constant at .5. The data from all three experiments were analyzed according to a detection model describing performance in multiple-stimulus two-response procedures. This model provided independent measures of stimulus discriminability, contingency discriminability, and bias. The analysis showed that (a) consistent with the color-naming function, pigeons were better able to discriminate between higher nanometer values than lower nanometer values; (b) their ability to discriminate between the stimuli was independent of the number of wavelengths comprising each stimulus set; (c) they allocated delivered reinforcers very accurately to the previously emitted response; and (d) no consistent biases emerged.
Journal of the experimental analysis of behavior, 1989 · doi:10.1901/jeab.1989.51-291