Contrast and undermatching with regular or irregular alternation of components.
In multiple schedules, making transitions between rich and lean conditions predictable doesn't change contrast or matching - use whatever alternation pattern works best for your client and setting.
01Research in Context
What this study did
Szatmari et al. (1994) tested whether the predictability of schedule changes affects contrast and matching. They used pigeons in a laboratory setting with multiple VI schedules. The birds experienced two types of alternation: regular (fixed order) and irregular (random order).
The researchers measured response rates and contrast magnitude in both conditions. They wanted to see if knowing when a schedule change would happen influenced behavior.
What they found
The study found no difference between regular and irregular alternation. Contrast magnitude remained the same whether pigeons could predict the upcoming schedule change or not. Response-ratio sensitivity also stayed constant across both conditions.
These results suggest that predictability of schedule alternation doesn't drive contrast or matching effects.
How this fits with other research
This finding challenges what Elliffe et al. (2003) found with concurrent schedules. They showed that signaling upcoming alternatives did affect choice behavior. However, Szatmari et al. (1994) used multiple schedules instead of concurrent ones - this schedule difference likely explains the opposing results.
The study extends McLean et al. (1981), which showed that contrast effects peak early in components. The 1994 work adds that this time-based pattern happens regardless of alternation predictability. It also builds on Szatmari (1992), which demonstrated reinforcer reallocation between components - the new finding shows this mechanism operates independently of alternation regularity.
Sturmey (1995) later showed that longer component durations reduce contrast. Combined with the 1994 results, this suggests timing matters within components, but predictability of when components change does not.
Why it matters
For BCBAs using multiple schedules in treatment, this means you don't need to worry about making schedule transitions predictable. Whether you alternate rich and lean reinforcement conditions regularly or randomly, the contrast effects will be similar. Focus instead on component duration and reinforcement ratios, as these do impact behavior. This simplifies schedule implementation - you can vary transition timing based on practical needs without affecting treatment efficacy.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Stop trying to make multiple schedule transitions predictable - alternate between rich and lean conditions based on client needs and session flow, not on a fixed pattern.
02At a glance
03Original abstract
Behavioral contrast and response-ratio sensitivity to reinforcement were compared in multiple schedules in which components alternated strictly or according to a pseudorandom sequence. Average component durations in the two regimes were always 60 s, and order of presentation of component alternation regimes was counterbalanced across subjects. In Part 1, the reinforcer rate in one component was reduced from 60 per hour to zero, while that in the other component was unchanged. Positive behavioral contrast occurred in the constant component in that response rates increased, but neither the reliability nor the magnitude of contrast was affected by the manner in which components alternated. Part 2 was similar, except that a number of different reinforcer rates were used in the varied component. Neither contrast nor sensitivity of response ratios to changes in reinforcer ratios depended on the regime of component alternation. Thus, the predictability in time of future reinforcement conditions, which is a feature of regular multiple scheduling, does not appear to be a determinant of multiple-schedule performance.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.61-407