Low-IQ deficit in intradimensional discrimination shift despite overtraining and verbal feedback

One hundred and twenty low-IQ and average-IQ children (MA 5 to 7 years) were required to learn a 2-choice discrimination involving verbal and manual responses, with verbal correction of errors, before proceeding to an intradimensional shift with new color cues. One-half of each group also received 100 interpolated trials (overtraining) on the original task. Results disclosed a low-IQ deficit during original learning, which was absent during overtraining but recurred in the final phase, undiminished by either overtraining or verbal feedback conditions applied during the transfer phase. The findings oppose a theoretical explanation based on probability of attending to color, since the inference that this probability approximated 1 for all subjects was amply justified, thus emphasizing the need for alternative interpretations of the retarded subjects' difficulty.