Modeling strategy shifts in a problem-solving task

A computer simulation model was fitted to human laboratory data for the Missionaries and Cannibals task to explain (1) the effects upon problem performance of giving a hint, and (2) the effects of solving the problem a second time after one successful solution had been achieved. Most of the variance in the relative frequencies of different moves can be explained by positing that the effect of the hint, or of previous experience in solving the problem, is to cause subjects to switch more promptly from a strategy of balancing the numbers of missionaries and cannibals on both sides of the river, to a means-ends strategy.     

On the relation between visual surround and motion aftereffect velocity

Two experiments examined the effect of changes in the visual surround upon the velocity of motion aftereffects. Experiment I showed that introduction or reintroduction of a patterned surround midway through the test period was sufficient to produce an increase in apparent velocity. However, a greater increase was observed when a patterned surround instead of a dark homogeneous surround had been used during the induction period. Experiment II demonstrated that luminance change was also sufficient to produce an increase in apparent velocity, although the extent of the increase was not as great as that produced through the use of the patterned surround in Experiment I. These results indicate that a change in stimulus surround is sufficient to produce an increase in the velocity of a motion aftereffect and that the extent of the increase is dependent upon the characteristics of both the induction and test surrounds.     

On the process of comparing sentences against pictures

The present study outlines a theory of how people compare sentences against pictures. This theory was tested in four experiments in which Ss were timed as they judged whether a sentence (e.g., Star isn't above plus) was true or false of a picture (e.g., ⁺_∗). The latencies in these tasks were consistent with the thesis that: (1) sentences are represented in terms of elementary propositions; (2) pictures are encoded in the same interpretive format; (3) these two codes are compared in an algorithmic series of mental operations, each of which contributes additively to the response latency; and (4) sentence encoding, picture encoding, comparing, and responding are four serially ordered stages, and their component latencies are additive. From these results, it was also possible to rule out certain explanations based on visual imagery, conversion (e.g., converting isn't above into is below), reading time, normative word frequencies, and other factors. Finally, it was shown that this theory is consistent with previous studies on sentence comprehension, sentence verification, concept verification, and other related phenomena.     

A comparative analysis of two community stressors' long-term mental health effects

The investigation directly compared the long-term mental health consequences of two community-wide stressors, the Three Mile Island (TMI) nuclear accident and widespread unemployment due to layoff, in demographically comparable samples of women. Results showed a marked degree of similarity in the stressors' effects: Levels of subclinical symptomatology were elevated to similar degrees in each sample during the year following stressor onset, and symptom levels remained elevated in each sample 2 to 3 1/2 years later. Moreover, variables identified as predictors of enduring psychological distress were virtually identical for the two samples. Additional analyses revealed that the mental health status of unemployed husbands mediated the negative psychological effects of layoff on their wives. Implications of these results for understanding the long-term consequences of exposure to community-wide stress are discussed.     

Replication of empirically derived syndromes as a basis for taxonomy of child/adolescent psychopathology

To advance the empirical identification of child/adolescent syndromes, principal components analyses were performed on four sets of parents' ratings of 8,194 6- to 16-year-olds referred to American and Dutch mental health services. The following syndromes replicated well for both sexes at ages 6-16: Aggressive, Anxious/Depressed, Attention Problems, Delinquent, Somatic Complaints, and Withdrawn. For both age ranges, a syndrome designated as Socially Inept replicated well among boys, and one designated as Mean replicated well among girls. Evidence was also found for a Schizoid syndrome in all sex/age groups and a Sex Problems syndrome among girls at ages 6-11. Syndrome scores discriminated well between nationwide normative and clinical samples. The replicated syndromes contribute to the empirical basis for a taxonomy of the kinds of disorders commonly seen between the ages of 6 and 16.     

Visual laterality effects: A signal detection analysis

Subjects were asked to indicate, by a simple motor response, the presence or absence of a pre-designated target letter in unilaterally presented consonant trigrams. For horizontally oriented stimuli (Experiment 1), perceptual sensitivity was greater in the right visual hemifield. For vertically oriented stimuli (Experiment 2), perceptual sensitivity did not differ between visual hemifields. Decision making was less conservative and reaction time was shorter with right hemifield presentation, regardless of stimulus orientation. Practice effects and serial position curves were examined. Implications of these results attribute laterality effects to iconic scanning patterns and to postperceptual decision processes.     

Tenacious inferential illusions: Experimental fact vs. critical fancy

Tzeng and Tzeng's (1982) assertion that the results from two indices of estimated item coendorsement should not have been combined in Mirels' (1976) demonstration of inferential illusions is shown to be based on erroneous suppositions. Evidence for the equivalence of the two formats makes it clear that the separate presentation of data for each index would have yielded results and led to conclusions virtually identical to those for the combined data. The objection by Tzeng and Tzeng to Mirels' use of empirical conditional probabilities as a criterion against which to assess the veridicality of Implicit Personality Theory is also shown to be without empirical foundation. In the light of available findings, the existence of striking inaccuracies in the culturally prevalent Implicit Personality Theory seems well established.     

The effect of texture on tactually perceived length

A curvilinear relationship between texture and perceived length was investigated in. two experiments. In Experiment 1 the perceived lengths of four grades of emery cloth and an untextured stimulus were compared in a forced-choice procedure. Generally, as predicted, fine-texture stimuli were perceived as longer than coarse-textured stimuli. Experiment 2 attempted to modify the biasing effect of texture by employing preliminary training with fine or coarse textures. Although unsuccessful in modifying the bias, the curvilinear relationship between texture and perceived length was agmn supported. Some implications for constructing teaching materials for the blind are discussed.     

Semantic distinctions and memory for complex sentences

This investigation studied what people remember in recalling complex sentences, whether it is certain semantic distinctions or merely transformational markers. After short intervals 24 subjects tried to recall sentences of six kinds which formed paraphrase sets: S₁ before S₂, S₁ and then S₂, After S₁ S₂, S₂ after S₁, S₂ but first S₁, and Before S₂ S₁. (S₁ and S₂ denote first and second clauses in temporal, not linguistic, order.) Subjects remembered the underlying sense of sentences with S₁-S₂ clause ordering better than those with S₂-S₁ clause ordering, regardless of transformational complexity. Subjects also showed a response bias, hence better verbatim recall, for sentences with subordinate clause second and for sentences with S₁-S₂ clause ordering. Sentence confusions indicated that subjects remembered three semantic distinctions: the temporal order, order of mention, and main-subordinate relation of the two described events. A theory of memory for marked and unmarked semantic distinctions was used to account for the results.