Evidence against an occasion setting account of avoidance learning

Earlier studies on human avoidance learning showed that an avoidance response reduces the expectancy that a warning stimulus (WS) will be followed by an unconditioned stimulus (US). This modulation can transfer to WSs with which the avoidance response did not occur in the past. Recent studies suggest that transfer of modulation is selective in that it is stronger for WSs that previously went together with other avoidance responses than for WSs that never went together with an avoidance response. This finding has been interpreted as providing unique support for an occasion setting account of avoidance learning. We put forward alternative explanations of selective transfer of modulation in terms of the rate with which a WS was reinforced in the absence an avoidance response. In support of the alternative explanations, we found that transfer of modulation depended not on whether a WS previously went together with another avoidance response but on the rate with which the WS was reinforced in the past. We conclude that selective transfer of modulation in avoidance learning does not provide (unique) support for the occasion setting account. Our findings are in line with a revised expectancy model of avoidance learning.