Effects of fixed-ratio sample and choice response requirements upon oddity matching.

The team used pigeons in an oddity-matching task. Birds had to peck a center key that did NOT match either side key.

Before the sample appeared, the pigeon completed a fixed number of pecks. Before choosing, it completed a second fixed number. The researchers changed both numbers across conditions to see how extra work changed accuracy.

More pecks before the sample raised accuracy. More pecks before the choice lowered accuracy.

The first result shows extra effort can sharpen stimulus control. The second shows too much work right before the choice can blur it.

Lydersen et al. (1974) had already shown that the time between the first and last response—not the count—controlled discrimination. The new study keeps the time idea but adds that the placement of the work also matters.

Perez et al. (2020) later blocked the correct comparison during matching-to-sample and saw errors rise. Both papers warn that limiting or overloading the view of the right stimulus hurts learning.

Reed (2012) found that any delay between sample and comparison worsened over-selectivity. Gardner et al. (1977) show that extra response steps can act like a delay and produce a similar drop.

When you ask a learner to do several tasks before showing the critical stimulus, you may boost attention. When you pile responses between the stimulus and the response, you risk losing that attention.

Try inserting a brief motor warm-up before you show the sample, but keep the choice phase quick and easy. This simple tweak can tighten stimulus control in conditional-discrimination drills.