The effect of training and stimulus variables on the reversal-shift ontogeny

Linear functions fitted to the proportion of optional reversal-shifts as a function of log CA were used to assess the effect of stimulus and training variables on the reversal-shift ontogeny. The results were: (1) when the dimensional salience of the two sets of cues in the stimulus compound were similar, there was no significantly different effect of size, color, or form cues on the rate parameter, suggesting that the rates of mediational development for these cues are similar. Reversal-shifts were, however, more likely with the color-form compound than with the size-color compounds throughout the tested age span, indicating that some stimulus conditions are more likely than others to produce mediated processing at all age levels. (2) The facilitative effects of labelling on reversal-shifts were greatest at the younger ages and decreased systematically over age. (3) Overtraining increased reversal-shifts at most ages but whether the facilitative effect interacts with age remains moot. (4) Neither labelling nor overtraining eliminated ontogenetic differences.