Transverse compounding in the discriminative learning of moderately and mildly mentally retarded adolescents

For adolescents in the range of moderate to mild retardation, the salience of transverse compound stimuli (combinations of positive and negative cues) was found to be low in two-choice visual discriminations. In problems allowing optional use of transverse compounds, no use whatever was made of these stimuli. In problems requiring use of transverse compounds, only the more intelligent subjects were able to learn to attend to such compounds, but this learned salience faded in a new problem that allowed optional compound use. These results were interpreted as an instance of developmental changes in unlearned stimulus salience hierarchies. We speculated that the low saliency of transverse compounds may be related to reading difficulties.