Cognitive reference points

Two methods were used to test the hypothesis that natural categories (such as colors, line orientations, and numbers) have reference point stimuli (such as focal colors, vertical and horizontal lines, and numbers that are multiples of 10) in relation to which other stimuli of the category are judged. In Experiment I, subjects placed pairs of stimuli into sentence frames consisting of linguistic “hedges” such as “— is essentially—.” Results were that the supposed reference stimuli were most often placed in the second (reference) slot. In Experiment II, the subject placed a stimulus in physical space to represent his feeling of the psychological distance of that stimulus from another spatially fixed stimulus. Results showed that, when supposed reference stimuli were fixed, other stimuli were placed closer to them than vice versa. The results have substantive implications for the understanding of internal structure of categories and methodological implications for the mapping of reference points, quantification of linguistic intuitions, and the assumption of symmetry in psychological distance judgments.     

Choosing between fixed time and variable time shock

Two experiments are reported dealing with choice of fixed or variable time shock schedules with and without signals. Response independent shock was presented on either a fixed-time or a variable-time schedule and subjects could change from one condition to the other for short periods after which the initial condition was automatically reinstated. In the first experiment shocks for both schedules were either unsignalled (6 subjects) or signalled (3 subjects) and all subjects changed from a schedule of variable-time shock to a fixed-time one. Subjects that were given the opportunity to change in the reverse direction did not do so. Opposite findings were obtained in the second experiment (7 subjects) comparing unsignalled fixed-time shock with signalled variable-time shock. Six of the seven subjects changed from the fixed-time schedule to the signalled variable-time one but not the reverse. The data were considered consistent with an analysis of choice based on the reinforcing value of discriminable shock-free periods.     

Odor as a conditioned inhibitor: Applicability of the Rescorla-Wagner model to feeding behavior

Hooded rats were given conditioned inhibition training in which the taste of saccharin alone was always followed by induced illness, but the taste of saccharin plus the odor of amyl acetate was not. In a series of three subsequent tests—summation, enhancement of conditioning, and retardation—it was demonstrated that the odor had acquired active inhibitory properties. The results paralleled those obtained with more traditionally studied stimuli and techniques and hence were found to be readily predictable from a recent model of conditioning set forth by Rescorla and Wagner (1972).     

Child judgments of sentences varying in grammatical complexity

This study is another contribution to the development of a satisfactory child version of the linguistic task of judging grammaticality. With a nondifferentially reinforced forced-choice procedure, it was found that responses of 24 5- and 24 7-yr-old children did vary as a function of the grammatical complexity of stimulus sentences. The children judged sentence stimuli of two types (negatives and wh-word questions) each having three levels of grammatical complexity (two primitive and one well-formed). After each stimulus presentation, the subject pointed to the adult or the child in a photograph, depending on who was judged to have produced that utterance. Performance of the two age groups did not differ for the question stimuli, for which subjects pointed to the adult more frequently as the grammatical complexity of wh-word questions increased. In response to the negative sentences, the older group attributed more well-formed stimuli to the adult than primitive ones. While the younger group pointed to the adult more frequently for well-formed negatives than for the middle level negatives, they made more adult responses than expected to the least complex negatives. It was concluded that, with this procedure, 5- and 7-yr-olds demonstrate ability to distinguish grammatically well-formed from primitive sentences. Procedural improvements for future research may allow children this age and younger to demonstrate more adult-like discrimination between a variety of primitive and well-formed sentences.     

Oral overcorrection: side effects and extended applications.

Experiment 1: In a specialized daycare program the use of oral overcorrection (contingent toothbrushing with an oral antiseptic) to suppress one child's thumbsucking at Language Time was found to suppress the behavior of another child who was not treated but who witnessed the target child's treatment. Experiment 2: The main effects of oral overcorrection were replicated. Contingent overcorrection threats (warnings), used independently, were then shown to suppress thumbsucking behavior that had returned to its baseline level. These effects were maintained one month after the threats were discontinued, but they did not generalize to other activity periods, particularly Nap Time. Experiment 3: Contingent threats were found to suppress the persistent nap-time thumbsucking of the child from Expt 2. Increments in certain other (nonoral) inappropriate behaviors were correlated with the suppression of thumbsucking. Threats to use oral overcorrection contingent upon nonoral misbehaviors at Nap Time were not effective. However, the actual use of oral overcorrection for these categories of nonoral misbehavior served to suppress these behaviors. Experimental controls combined treatment reversal and multiple baseline single-subject designs.     

Span and rate of apprehension in children and adults.

Children and adults quantified random patterns of dots, under unlimited exposure duration. For adults and children two distinct processes appear to operate. For adults the quantification of collections of from one to three dots is essentially errorless, and proceeds at the rate of 46 msec per item, while the quantification rate for from 4 to 10 dots is 307 msec per dot. For children the same operating ranges appear to hold, however children are much slower. The lower slope is 195 msec per dot, while the upper is 1049. Although the results for adults and children are similar except for the overall rates, the nature of the isomorphism between children and adults is unclear.     

Establishing discriminative stimulus control within generalized oddity performance,without reinforcement

In two oddity learning studies with children, subjects were reinforced for oddity (or nonoddity) responding on line-tilt or dot numerosity problems. Interposed form and color problems were not reinforced. No instructions to make oddity choices were given. In Experiment I it was found that reinforcement for oddity or nonoddity responding on tilt and numerosity problems produced the corresponding tendency toward oddity or nonoddity performance on these problems and also on the nonreinforced form and color problems. These results show a generalized oddity phenomenon similar to generalized imitation. In Experiment II a third type of nonreinforced problem was presented in this same format: compound stimuli permitting either a color or a form solution. It was found that immediate prior training with nonreinforced form problems, interpolated among the reinforced tilt and numerosity problems, led to form-oddity choices in the compound problems. Similarily, color pretraining produced color-oddity choices. These results show that selective discriminative stimulus control can be obtained in oddity learning, without reinforcement for choices on either of the two dimensions involved.