Categorizing Externally Distributed Stimulus Samples for Unequal Molar Probabilities

Abstract

40 Ss categorized random samples from one of two normal distributions and then received feedback. The over-all, molar probabilities of samples for the two distributions were .35 and .65. Problem-solving or Gambling instructions, and distributions on a Dot position or a Number continuum, were combined factorially with sex. There were no main instructional effects. Performance was superior on the position continuum ( p < .01). Over-all performance resembled micromatching of probabilities at each continuum position, but some Ss responded independently of sample position. The molar probability of response “1” for the Dot group was less (.295) than the molar reinforcement level ( p < .001). There were no main sex effects. Distance between centers was overestimated for Dot but not for the Number continuum.