Abstract:
The major aim of this thesis was to relate the stimulus-compounding paradigm of the operant literature, to other multidimensional stimulus-control paradigms at both theoretical and methodological levels. In two experiments pigeons were trained with two-element compound discriminative stimuli varying either inter-dimensionally (as in the compounding paradigm) or intradimensionally on auditory and visual dimensions. In a third experiment the elements of the compound controlled topographically different responses. In all experiments, both stimulus dimensions excercised control in their own right, but there was also an interaction factor of significance. Thus neither a unidimensional theory (such as Weiss' 'Composite continuum' model) nor any theory proposing independent control by two orthogonal dimensions (such as Weiss' stimulus-element analysis or a simple interaction-of-marginal-gradients approach) were entirely adequate. An attentional theory was advanced which involved a variable degree of interaction between the two stimulus dimensions of the compound, maximal summation being achieved when the interaction was minimal.