Vibrotactile masking: Effects of multiple maskers

Threshold elevations (TE) were determined at a testsite on the left thigh with the simultaneous presentation of combinations of maskers positioned on the trunk. It was found that the resultant TE from groups of up to 10 multiple maskers is nearly equal to the addition of the TE produced by each masker separately.     

Two operations In character recognition: A partial replication

Subjects carried out a choice reaction time experiment in which they were required to press one lever ifa tachistoscopically flashed numeral was a member of a previously memorized list of numerals and a second lever if it was not a member of the list. The number of numerals in the list was varied from one to four. On half of the trials the numeral was partially masked by a pattern of visual noise. For one group a single fixed pattern of noise was used; for a second group four patterns presented in random order were used. Reaction time from the onset of the numeral to the lever press was found to be a linear function of list size, confirming Sternberg’s hypothesis that the list is scanned serially to determine a match. Partial masking was found to add a constant increment to reaction time for both groups, independent of set size. The increment was equal for both groups. The constancy of the reaction time increase contradicts Sternberg’s results in which the increment was found to be, in part, a function of list size. The results of the present study indicate that one cannot dismiss the possibility that Ss identify the character to the point of labeling prior to an attempt to determine list membership.     

The uniqueness and significance of simple structure demonstrated by contrasting organic “natural structure” and “random structure” data

The study compares the extent to which naturally structured data and artificial, relatively random data (both with the same basic parameters) produce simple structure factors which are uniquely determined. Two examples of unstructured matrices were compared with the ball problem matrix. The results show that an oblique position of maximum hyperplane count in the structured data differs from that in the unstructured by reaching a significantly more unique position in terms of the exactitude with which it is re-discoverable when starting from different positions, and by reaching (at the maximum) a significantly higher hyperplane count.     

Effects of pentobarbital on fixed-ratio reinforcement,

Certain doses of pentobarbital consistently increased the rate of pecking engendered by a fixed-ratio schedule of 30 responses in a group of 13 pigeons, and still higher doses produced decrements in rate of responding. For individual subjects, the dose-effect functions were qualitatively similar, but differed with respect to the doses producing the maximum increase and subsequent decrease in rate. In general, the maximum occurred at lower doses and the decrement was greater at the highest dose in the birds with the highest control rates. It was also possible to distinguish between the effects of pentobarbital and several other drugs on the behavior maintained by FR 30. The results indicate that changes in rate of responding on FR 30 after drug administration are dose-dependent, drug-specific effects.     

Generalization of auditory intensity as a function of small amounts of discrimination training

Rats were trained on a two-valued auditory-intensity discrimination for 5, 2, 1 or 0 days. Then, the bar-press response rate was sampled in the presence of seven added discrimination stimuli (generalization) for seven days. Daily training sessions were 4 hr in length throughout the experiment. Only the five-day group exhibited a marked superiority on the multi-valued discrimination when contrasted with the group having had no prior simple discrimination training.     

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.     

Simulation of human problem-solving behavior

In the simulation of human behavior on a digital computer, one first attempts to discover the manner in which subjects (Ss) internally represent the environment and the rules that they employ for acting upon this representation. The interaction between the rules and the environmental representation over a period of time constitutes a set of processes. Processes can be expressed as flow charts which, in turn, are stated formally in terms of a computer program. The program serves as a theory which is tested by executing the program on a computer and comparing the machine's performance with S's behavior.