STIMULUS SELECTION IN VERBAL LEARNING
Benton J. Underwood
This paper deals with discrepancies between the apparent stimulus term and the actual stimulus in verbal learning experiments. The stimulus term presented to the subject will be called the nominal stimulus; the characteristic or characteristics of the stimulus which the subject actually "uses" to cue a response will be called the functional stimulus. Thus, this inquiry is concerned with potential discrepancies between the nominal and functional stimulus--between what the investigator commonly assumes to be the stimulus and what in fact serves functionally as the stimulus.
Theories, or other analytical devices, inevitably make assumptions about the functional stimulus; generally speaking, this assumption is that the functional stimulus and nominal stimulus are identical. That is to say, if the nominal stimulus is qor, it is usually assumed that all apparent characteristics of qor serve as the functional stimulus or, perhaps more accurately, serve as the stimulus compound. In so far as there are discrepancies between the functional and nominal stimulus, the investigator may be misled. Whatever the implications of such discrepancies (if they exist), the search for them could be pursued as an area of investigation in its own right. But if theories make isomorphic assumptions about the nominal and functional stimulus, it might be argued that the search for discrepancies is propaedeutic to theories. However that may be--and certainly theories cannot wait for all necessary data--there seems to have been little systematic empirical attention given in verbal learning to the potential discrepancies under discussion. Of necessity, therefore, the present discourse will be rather short on data and long on speculation.
The problem of discrepancies between nominal and functional stimuli is not a new one for other areas of learning, particularly animal learning. Certain critical theoretical issues in discrimination learning revolve around what aspect or what components of the stimulus situation