STIMULUS CONTROL ACQUIRED BY COMPONENTS OF TWO COLOR‐FORM COMPOUND STIMULI¹

Abstract

Four pigeons were trained to respond on one of two keys in the presence of one color-form display, and on the other key when a second color-form display was present. Both responses were maintained on a 2-min variable-internal schedule of reinforcement. Subsequently, stimulus control acquired by components of the compound stimuli was determined by brief test probes in which the colors and forms separately, and in novel combinations, appeared on the display screen. When either color component was present, both choice of response key and response rate were like responding to the training compound display containing that color. When the forms were presented separate from the colors, generally low and comparable rates of responding occurred on both keys. Jenkins (1965) described some of the difficulties associated with identifying the controlling stimulus (stimuli) in discrimination learning. In the typical discrimination setting, the mere fact that an organism responds differently to each of two stimuli is evidence of stimulus control. However, this fact alone cannot be used to assign control to one or both of the stimuli; responding may be regulated by the presence or absence of either one of the stimuli, or each stimiulus may control its separate response class.The problem of assigning stimulus control to one or more components of a complex stimulus is additionally complicated by the increased number of possible outcormes. To One of the major difficulties arising from use of a reinforcement-extinction or "go/no go" procedure in studies of selective attention is that the expected rate of occurrence of responses in the presence of "neutral" stimuli is not clearly different than the expected rate of occurrence of responses in the presence of SA.After typical discrimination training procedures, both an SA and a "neutral" stimulus become the occasion for a very low rate of key pecking. Therefore, under these circumstances, it will usually be difficult to separate an absence of stimulus control from the presence of stimulus control by components of SA. However, by using a two-key chamber, and de-437 1969, 12, 43-7-442 NUMBER 3 (MAY)

Discrimination and Attention in Dogs

“…After the subject's discriminative responding achieves an acquisition criterion, usually based on response accuracy, components of the compound stimulus are presented singularly and in reverse juxtaposition, in "test trial" or "probe" fashion (Born & Peterson, 1969). The test stimulus component in the presence of which discriminative responding approximates prior criterion levels is considered to have acquired effective control of the behavior, that is, to function as the discriminative stimulus (SD) .…”

The role of test stimuli in matching to compound samples by pigeons

“…Demonstrations of selective stimulus control have taken two forms. If responses are reinforced in' the presence of a compound stimulus, some elements come to control responding and others do not (e.g., Born & Peterson, 1969;Reynolds, 1961). If responses are reinforced in the presence of Element A, and then reinforced in the presence of Compound AB, Element B assumes little if any control over responding (e.g., Johnson & Cumming, 1968;Kamin, 1969).…”

“…The rule has been phrased in different ways (Born & Peterson, 1969;Mackintosh, 1965), but it essentially states that " ...the degree of control exerted by one element of a compound stimulus is inversely related to the stimulus control exerted by other elements of the compound" (Maki & Leith, 1973, p. 348). There are two major implications.…”

Effects of stimulus dimension and of trial and intertrial illumination on acquisition of a match/mismatch task by pigeons

“…Studies of delayed matching-to-sample have consistently found that memory for color samples is better than memory for form samples (e.g., Cook, 1980; Farthing, Wagner, Gilmour, & Waxman, 1977). Other studies have alsoshown that when color and form stimuli are combined to produce stimulus compounds, pigeons may selectively attend to the color element of the compound (e.g., Born & Peterson, 1969; Seraganian, 1979).The reason for this difference in the discriminability of colors and shapes is not clear. However, we recently reported the results of a study that suggested that the discriminability of forms, but not colors, may vary systemThe authors wish to thank Pamela Jackson for her assistance in running subjects and Marcia Spetch for her helpful comments on an earlier version of the manuscript.…”

“…Studies of delayed matching-to-sample have consistently found that memory for color samples is better than memory for form samples (e.g., Cook, 1980; Farthing, Wagner, Gilmour, & Waxman, 1977). Other studies have alsoshown that when color and form stimuli are combined to produce stimulus compounds, pigeons may selectively attend to the color element of the compound (e.g., Born & Peterson, 1969; Seraganian, 1979).…”