Stimulus Equivalence: Effects Of A Default-response Option On Emergence Of Untrained Stimulus Relations.
A ‘none’ button on equivalence tests drops pass rates from 94 % to 41 %—drop the button.
01Research in Context
What this study did
Researchers taught college students to match abstract pictures.
Half the students could press a ‘none of these’ button during tests.
The rest had to pick one of the pictures shown.
Everyone got the same training; only the test button changed.
What they found
Without the ‘none’ button, 94 % of students showed new untrained matches.
With the button, only 41 % showed those matches.
Reflexivity tests—matching a picture to itself—fell the most.
The simple extra choice cut equivalence emergence in half.
How this fits with other research
Emmelkamp et al. (1986) saw the opposite pattern: kids with language formed classes, kids without did not.
The two studies seem to clash, but they tested different things.
M et al. looked at language skill; A et al. looked at response options.
Both warn that small procedural tweaks can hide true learning.
Saunders et al. (1988) already showed classes can grow without extra rewards.
A et al. add that extra response choices can still choke that growth.
Why it matters
When you probe for emergent skills, skip the ‘I don’t know’ or ‘none’ box unless you must have it.
The option gives learners an easy escape and can make it look like equivalence failed when it really didn’t.
Run clean probes: present the stimuli and require a pick.
You will get a clearer picture of what your learner actually derived.
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02At a glance
03Original abstract
Default‐response options, intended to measure uncertainty, sometimes are included in discrete‐choice measurement in an attempt to clarify stimulus control of remaining response options. Recent experiments have used a default‐response procedure to investigate emergent stimulus relations, but no study to date has compared effects of different default‐response procedures on emergence of the untrained relations that define stimulus equivalence. Five groups of college undergraduates (each n = 16) completed a conditional discrimination training procedure to instate the stimulus relations prerequisite to three three‐member equivalence classes; a training review intermingling all of the explicitly trained relations; and tests for emergent relations. The groups differed in terms of (a) presence versus absence of a “none” option during emergent relations tests and (b) the amount of experience with “catch trials” in which “none” was the correct selection. Stimulus equivalence was demonstrated in 94% of subjects in a control group who were trained and tested without the “none” response option and without catch trials and in 41% of subjects in the “none” groups. Among subjects in the “none” groups who failed to demonstrate equivalence initially, 95% did so when retested under control‐group conditions. Across “none” groups, probability of equivalence class formation was positively correlated with amount of experimental experience with catch trials in preliminary training and equivalence testing. Among the emergent relations defining stimulus equivalence, reflexivity was most often precluded by the “none” option, although there was evidence of group differences in relation specificity. These results suggest that a default‐response option can interfere with the formation of emergent relations, and that the effects are contextually sensitive. Although there may be advantages to employing default‐response procedures in studies of emergent stimulus relations, the responses they control should be viewed as behavior under specific stimulus control rather than a generic expression of uncertainty
Journal of the experimental analysis of behavior, 1998 · doi:10.1901/jeab.1998.70-87