Polydipsia induced in the rat by a second-order schedule

Drinking was studied in rats pressing a bar on a second-order schedule in which every third completion of a 1-min fixed interval was followed by food presentation. A brief flash of light signaled the completion of each fixed-interval component. The rats drank not only after the food presentations but also after presentations of the light flash alone. A high rate of steady drinking followed intervals terminated by a food presentation. Drinking that followed intervals terminated by a light flash alone was of comparable rate, but characteristically interrupted by bar pressing. When 250-mg food pellets were used instead of 45-mg pellets, both drinking and bar-pressing rates increased substantially.     

Orientation of letters and errors in their recognition

Subjects named alphabetic characters that had been rotated, reflected, or inverted. Inversions induce more errors than mirror reflections and reflections induce more than rotations. In a significant number of mistakes a transformed character was assumed to be normally oriented, but in most a transformed character was confused with the mirror image of the original. The data suggest the existence of an “orientation set” in which the identiflcation of ambiguous characters depends largely on their anticipated orientation. The individuality of the data for the different orientations suggests that different transformations are compensated for in part by different mechanisms.     

The effect of two schedules of primary and conditioned reinforcement

Of 23 pigeons, 11 received continuous reinforcement for key pecking, and 12 received an FR 10 schedule of reinforcement. The birds were then tested without food, but with potential conditioned reinforcers presented either on the same schedule as in training, on the other schedule, or not at all. Each bird in the subgroup trained on CRF and tested with S^r's at FR 10 not only gave more responses in testing than did each bird in both subgroups receiving no S^r's, but also gave more responses than did each bird in the S^r subgroup receiving CRF training and S^r's at CRF. Cumulative records are presented to show the effects of different schedules of conditioned reinforcers.     

Latency of different verbal responses to the same stimulus

A response of reading (letter O) or of naming (circle) can be given to the same sign O. The verbal reaction time is higher when naming than when reading (difference 100 millisec.). This fact verifies that naming is a longer process than reading, the difficulty of perceiving the stimulus being equal.

The response “zero” which may be given to the same sign is nearer to the reading-response time than the naming-response. These facts can be explained if we say that uncertainty for coding concrete signs is greater than for alphabetical or numerical signs.     

Kinaesthetic judgements of the direction of line by young children

The ability of young children to make kinaesthetic judgements of direction of line has been studied under recognition and detection conditions. Some children were not more accurate than chance when they were required to indicate the same one of a pair of mirror image obliques lines over a series of trials; these children could, however, detect whether two obliques were oriented in the same direction or in different directions. These latter data suggest that the poor recognition of mirror image obliques arises from deficiencies in spatial categorizing and not in input coding. This conclusion is supported by the finding that children who performed poorly on the kinaesthetic recognition of obliques performed poorly on the visual recognition of these figures.     

Cortical steady-potential shifts in conditioning

Cortical steady-potential shifts obtained from nonpolarizing electrodes chronically implanted in freely moving cats and rats reveal cortical activation related to urgency of response to unconditional and conditional stimuli. Such shifts appear relatively independent of activation in the rhythmic electrocorticogram and are related to higher levels of activation. Shifting is found to be modulated by drive and level of learning, suggesting a correlation with the proposed reaction potential of Hull. Both approach and avoidance “urgency” are reflected in the onset slope and amplitude of SP shifts in a manner suggesting modulation of cortical activation by the effects of behavioral regulation of stimulus conditions.     

Orlo Strunk Jr.

Pastoral Psychology -