Sequential dependencies and response range in cross-modality matches of duration to loudness

Subjects matched durations of keypresses to loudnesses of pure tones. Resulting duration responses were found to be assimilated to the value of the immediately preceding stimulus and responses from one to at least six trials back in the sequence of loudness stimuli. Responses were contrasted with the values of stimuli two through six trials back in the sequence. These sequential dependencies and other properties of the data were predicted by a cognitive model in which cross-modality matches are mediated by category judgments of stimuli on both continua, and subjects use heuristic strategies to reduce response uncertainty.     

Use of markov-encoded sequential information in numerical signal detection

Twelve Ss made binary decisions with feedback on numbers from one of two normal distributions with equal variances and unequal means. Sequences of distribution choices corresponded to first-order two-state Markov processes with probabilities of change of state of p₁ = p₂ = .50, p₁ = p₂ = .75, and p₁ = p₂ = .25. Performance was best (in d’ terms) when p₁ = p₂ ≠ .50. First-order sequential response dependencies tended to mirror the first-order stimulus dependencies. Violations of a fixed cutoff point decision rule were concentrated in the region of the average critical point, with a bandwidth of about 1/2σ, in which violations were strikingly more frequent than would be expected if they had occurred randomly. These results imply that in this task Ss are using a criterion-band decision rule instead of a fixed cutoff point rule, and that they are basing decisions in the region of the criterion band on information extracted from the sequence of decisions presented to them. The average bandwidth is generally different from the optimum bandwidth used by an ideal O in combining the two sources of information.     

Temporal summation at the warmth threshold

Threshold levels for warmth aroused by infrared irradiation were measured in sLx Ss at durations between 0.05 and 10 sec. Beyond a critical duration of about a second, the threshold does not depend on duration. Below critical duration time t trades for irradiance ? by the formula ? = kt^?0.82. That these properties do not depend much on areal extent of stimulation was demonstrated by a study that compared temporal summation for two different areas of the same S’s skin. Individual differences in apparent absolute sensitivity were explored under the rubric of the theory of signal detection.     

Conditions affecting attempts to convert fate control to behavior control

This study examined the extent to which male and female subjects rewarded another like-sexed person as a function of his (her) performance, their fate control over his (her) rewards, and the extent to which he (she) had counterpower. Results supported hypotheses derived from social exchange theory and past studies of equity in that male (but not female) subjects tended to reward differentially the other most when their own payment was determined by his performance and they had high fate control. This effect, however, was not substantial, and, therefore, results suggest that persons are somewhat reluctant to convert their fate control to behavior control even under conditions in which such behavior is reasonable.     

Response system processes in absolute judgment

Consistent relationships are found between Ss′ absolute judgments of the value of a stimulus and the previous sequence of both stimuli and responses. The form and magnitude of these sequential effects are shown to depend on the presence or absence of feedback and on task difficulty. The pattern of the sequential effects found allows the conclusion that they are due to purely response-system processes. A two-stage model of the judgment process is proposed, and it is argued that observed assimilative effects account for the central tendency effects observed in category judgments.     

Two studies of visual search for word targets with controlled rates of presentation*

The two studies reported involve the visual search of word lists for a target item when the rate of presentation is controlled and the words are presented tachistoscopically. In the first study, the target is differentiated physically from the filler items by being capitalized. When the target is the last item in a list, it is readily identified at all presentation rates, but when it is the first word or is embedded in a list, recognition accuracy is inversely related to presentation rate. In the second study, the differentiation between target and filler items is in terms of the presence or absence of category membership. All Ss at all presentation rates do significantly better on lists with an animal word as a target and a set of unrelated words as filler items than on the converse arrangement.     

A technique for measuring thermoregulatory behavior in the fish

Apparatus and procedure are described for studying thermoregulatory behavior in fish. Results obtained with rainbow trout suggest that the described apparatus has several advantages over previously utilized devices.     

A note on Freeman's measure of association for relating an ordered to an unordered factor

Within the context of a contingency table, this note describes the relationship between Freeman's measure of association and the asymmetric association measures developed by Somers. The coefficient is appropriate for a contingency table in which the levels of one factor are ordered and the levels of the other factor are unordered; the indices defined by Somers are usually used when the levels of both factors are ordered and one is assumed to be the independent factor.     

Some applications of graph theory to clustering

This paper attempts to review and expand upon the relationship between graph theory and the clustering of a set of objects. Several graphtheoretic criteria are proposed for use within a general clustering paradigm as a means of developing procedures in between the extremes of complete-link and single-link hierarchical partitioning; these same ideas are then extended to include the more general problem of constructing subsets of objects with overlap. Finally, a number of related topics are surveyed within the general context of reinterpreting and justifying methods of clustering either through standard concepts in graph theory or their simple extensions.