The linear utility model for optimal selection

A linear utility model is introduced for optimal selection when several subpopulations of applicants are to be distinguished. Using this model, procedures are described for obtaining optimal cutting scores in subpopulations in quota-free as well as quota-restricted selection situations. The cutting scores are optimal in the sense that they maximize the overall expected utility of the selection process. The procedures are demonstrated with empirical data.     

“Impossible figures” and interpretations of polyhedral figures

The concept “impossible figure” is analyzed by formalizing the interpretations of a polyhedral figure by an observer, and defining several types of inconsistency in such interpretations. Tests for these inconsistencies are developed using simple graph theory, and a sufficient condition is established for the feasibility of an interpretation. Finally, techniques are derived for the automatic construction of usual or unusual multibar figures.     

Pavlovian conditioned stimulus effects upon instrumental choice behavior are reinforcer specific

In a transfer-of-control experiment with rats, Pavlovian CSs were tested for the specificity of their effects. The instrumental behavior consisted of a discriminative, conditional two-lever choice task in which qualitatively different appetitive reinforcers were contingent upon the two correct choices. In a Pavlovian phase, subjects experienced conditioning to establish either a CS⁺ or CS^? for one reinforcer or a CS⁺ or CS^? for the other reinforcer. Finally, in a test, these CSs were presented when there was the opportunity to make choice responses. The CS⁺s evoked choices of the lever which had eventuated in the reinforcer that had served as the Pavlovian US, while the CS^?s showed only a slight tendency to evoke the other choice responses. When the CSs were compounded with the original S^Ds, the CS⁺s had little effect upon the vigor of responding while the CS^?s reduced the vigor of responding to the S^D for the reinforcer that was the same as the US used in establishing the CS^?. The results are discussed in terms of associative mediational theory and the reinforcer specificity of Pavlovian conditioned excitation and inhibition.     

Choice reaction time with a random foreperiod

Choice reaction latencies were measured at three different a priori probabilities for two stimulus alternatives. Unlike the results of some other studies, the mean latency of a given response was nearly the same whether the response was correct or incorrect. The discriminable stimuli were a 1000- or a 1700-Hz tone presented at 70 dB SPL. Latencies and standard deviations, based on about 17,000 observations, are reported for three observers. The data are compared with predictions of the optimum sequential model of Wald and Stone and two modifications of that random-walk model, one proposed by Link and Heath and the other proposed by Laming. Fast-guess analyses were also carried out. The three-parameter version of either the sequential or the modified random-walk models provided reasonably accurate predictions of the mean data for each observer. The parameters estimated by the fast-guess analysis were unrealistic. There are three obvious differences between this experiment and most previous choice reaction-time experiments. First is stimulus modality#x2014;we used an auditory signal, whereas most of the previous studies used a visual signal. Second, the observers practiced more in this experiment than in most previous experiments. Finally, there was a random foreperiod with a heavy penalty for anticipations. One or more of these factors is the probable reason for the discrepancy between our results and those of previous studies.     

Attitude extremity,consensus and diagnosticity

Studied the effects of attitude extremity on perceived consensus and willingness to ascribe trait terms to others with either pro or anti nuclear attitudes. Results showed that attitude extremity affected consensus estimates. Trait attributions revealed a clear effect for valence, especially for the extreme attitude groups. Subjects with extreme attitudes also ascribed more traits to both pro and anti others than subjects with relatively moderate attitudes.     

Feature-specific interference in letter identification

It is a well documented finding that letter identification may be impaired by the presence of neighboring characters. There is much less agreement about the exact nature of such lateral interference. Evidence has been obtained for feature-specific interference, and even feature-specific facilitation. Santee and Egeth (1980) suggested that feature-specific interference will mainly be observed in data-limited situations where stimuli are presented for short durations and positional uncertainty is involved. They further suggested that interference would be revealed in accuracy rather than latency measures.In our first experiment, similar exposure conditions were used to those suggested by Santee and Egeth. In a second experiment, however, a longer exposure duration was used, and latency measurements were also collected. In a third experiment, positional uncertainty was removed by foveal presentation, and with this high quality stimulus presentation only latency measurements could be obtained.In all these experiments clear evidence for feature-specific interference was found, both in accuracy and latency data, and these results also held up under the detectability/criterion analysis proposed by Estes (1982). From these findings it can be concluded that feature-specific interference occurs under a wide range of conditions, including those representative of normal reading.     

Assertive training for agoraphobics

Twenty-one unassertive agoraphobic patients were assigned to one of three treatments: (1) prolonged exposure in vivo, (2) assertive training and (3) a combination of assertive training and prolonged exposure in vivo. Each treatment was conducted in groups which were led by two therapists. Assessments involved both phobic targets and assertiveness, and were made before and after treatment, and at 1-month follow-up. Exposure in vivo was found to be superior to assertive training on phobic targets. Assertive training produced greater gains in assertiveness than exposure in vivo. The combination of treatments produced results comparable to exposure in viro. Results indicated that the type of change produced by the treatments is a rather specific one and is related to the specific target of treatment.     

Structuring of early reaching movements: a longitudinal study

Reaches, performed by 5 infants, recorded at 19 weeks of age and every third week thereafter until 31 weeks of age, were studied quantitatively. Earlier findings about action units were confirmed. At all ages studied, movements were structured into phases of acceleration and deceleration. Reaching trajectories were found to be relatively straight within these units and to change direction between them. It was also found that at all ages, there was generally one dominating transport unit in each reach. The structuring of reaching movements changed in four important ways during the period studied. First, the sequential structuring became more systematic with age, with the dominating transport unit beginning the movement. Second, the duration of the transport unit became longer and covered a larger proportion of the approach. Third, the number of action units decreased with age, approaching the two-phase structure of adult reaching. Finally, reaching trajectories became straighter with age.     

Local and global mechanisms of one- and two-dimensional orientation illusions.

One-dimensional (1-D) orientation illusions induced on a test grating by a tilted and surrounding 1-D inducing grating have a well-known angular function that exhibits both repulsion and attraction effects. Two-dimensional (2-D) orientation illusions are those induced on a test grating by 2-D image modulation, such as a pair of superimposed inducing gratings at different orientations, usually orthogonal (a plaid). Given the known angular functions induced by the plaid component gratings, two hypotheses were developed that predicted different plaid-induced illusion functions. Hypothesis 1 states that the 1-D component-induced effects simply add linearly; Hypothesis 2 states that there is an additional mechanism that responds to the virtual axes of mirror symmetry of the plaid and adds to the effect. The data of two experiments were consistent with the predictions from the second hypothesis but not the first. Possible neural substrates of mechanisms that extract axes of symmetry are discussed; it is suggested that such global symmetry axes may underlie the perceived orientation of complex shapes.