The force of symmetry revisited: symmetry-to-noise ratios regulate (a)symmetry effects

Freyd and Tversky's [Am. J. Psychol. 97 (1984) 109] data suggested that human observers tend to overestimate relatively high levels of symmetry (symmetry effect), and tend to underestimate relatively low levels of symmetry (asymmetry effect). However, on the basis of their holographic approach to visual regularity, van der Helm and Leeuwenberg [Psychol. Rev. 103(3) (1996) 429] predicted that, at any level of symmetry, both symmetry and asymmetry effects may occur as a consequence of correct estimates of symmetry-to-noise ratios. This prediction was tested in two experiments, with tasks and stimuli similar to those in Freyd and Tversky's study. First, subjects had to judge whether a noisy symmetry is more similar to a slightly more symmetrical variant or to a slightly less symmetrical variant. Second, for every pair of stimuli in such a triadic comparison, subjects had to judge which stimulus is the more symmetrical one. The results from both experiments show that the occurrence of (a)symmetry effects indeed depends on symmetry-to-noise ratios.     

On quasivarieties and varieties as categories

Finitary quasivarieties are characterized categorically by the existence of colimits and of an abstractly finite, regularly projective regular generator G. Analogously, infinitary quasivarieties are characterized: one drops the assumption that G be abstractly finite. For (finitary) varieties the characterization is similar: the regular generator is assumed to be exactly projective, i.e., hom(G, –) is an exact functor. These results sharpen the classical characterization theorems of Lawvere, Isbell and other authors.Supported by the Czech Grant Agency (Project 201/02/0148).Special issue of Studia Logica: Algebraic Theory of Quasivarieties Presented by M. E. Adams, K. V. Adaricheva, W. Dziobiak, and A. V. Kravchenko     

Disposition to recognize goals in infant chimpanzees

Do nonhuman primates attribute goals to others? Traditional studies with chimpanzees provide equivocal evidence for “mind reading” in nonhuman primates. Here we adopt looking time, a methodology commonly used with human infants to test infant chimpanzees. In this experiment, four infant chimpanzees saw computer-generated stimuli that mimicked a goal-directed behavior. The baby chimps performed as well as human infants, namely, they were sensitive to the trajectories of the objects, thus suggesting that chimpanzees may be endowed with a disposition to understand goal-directed behaviors. The theoretical implications of these results are discussed.     

The role of specific consequences in the maintenance of three types of questions

This research replicated and extended a study by Williams, Donley, and Keller (2000). In that study, children with autism received a box with an object inside and learned to ask “What's that?,” “Can I see it?,” and “Can I have it?” to have the name of the object, to see the object, and to get the object, respectively. The purpose of the present research was to determine if the three questions (a) were three independent repertoires of behavior, (b) constituted three instances of a single functional response class, or (c) belonged to a chain of behavior. The 3 boys with autism who participated responded independently to each question when the consequences for each question were altered. This indicates that the three target responses were three independent repertoires of behavior, each one reinforced and maintained with its specific consequences. Thus, this procedure serves to teach children with autism to ask questions with flexibility according to a variable context.     

Limitations of the mnemonic-keyword method

The effectiveness of the mnemonic-keyword method was investigated in 4 experiments in which participants were required to learn the 1st-language (L1, Spanish) equivalents of a list of 30 2nd-language words (L2, Latin). Experiments 1 (adolescents) and 2 (adults) were designed to assess whether the keyword method was more effective than the rote method; the researcher supplied the keyword, and the participants were allowed to pace themselves through the list. Experiments 3 (adolescents) and 4 (adults) were similar to Experiments 1 and 2 except that the participants were also supplied with a drawing that illustrated the relationship between the keyword and the L1 target word. All the experiments were performed with groups of participants in their classrooms (i.e., not in a laboratory context). In all experiments, the rote method was significantly more effective than was the keyword method.     

Confidence judgments in event recall: developmental progression in the impact of question format

Two studies were conducted to examine developmental progression in children's and adults' ability to adequately monitor their own attempts to recall event details as well as the dependence of such metamemorial competencies on question formats. Eight and 10-year-old children as well as adults (Study 1, N=116; Study 2, N=60) rated their confidence when responding to specific questions about an observed event. Confirming most recent results, children and adults gave higher confidence ratings after correct than after incorrect answers. This ability, however, was limited to an unbiased question format. When being asked misleading questions, children's ability to differentiate was undermined, as reflected in equally high confidence judgments after correct and incorrect answers, even when the interview contained a mix of misleading and unbiased questions. When the interviewer "bombarded" the children with an uninterrupted series of misleading questions, children's difficulties appeared to be even more pronounced. These findings highlight the importance of the way in which questions are asked, and point to age-related progression in the relative impact of questioning style.     

Subgroup analysis of sex difference on the Vandenberg-Kuse mental rotation test

A large sex difference has been elicited on the Vandenberg-Kuse mental rotation test. Prior research emphasizes the biological root of this sex difference. In recent experiments we confirmed this viewpoint. A large sample was administered the test, and the distributions of scores for men and women (N = 138; 68 men and 70 women: ages 19 to 23 years). The mean scores were used as cut-off points to group the men and the women in different subgroups (Low/Women, High/Women, Low/Men, High/Men). There were large differences among all subgroups, reinforcing Kimura's testosterone hypothesis for sex differences in spatial ability.     

Empirical evaluation of the MCMI-III personality disorder scales

The MCMI-III personality disorder scales were empirically validated with a sample of 870 clinical patients and inmates. Prevalence rates of personality disorders were in general lower on the MCMI-III than clinical ratings, but trait prevalence was generally higher; thus a base rate of 75 on the MCMI-III could be a guideline in the screening of trait prevalence. However, the sensitivity of some MCMI-III scales was very low. Moreover, the correlations of most personality disorder scales of the MCMI-III were significant and positive with corresponding measures on clinical ratings and MMPI-2 personality disorder scales, but these were, in general, not significantly higher than some other correlations. As a consequence the discriminant validity seems to be questionable. The MCMI-III alone cannot be used as a diagnostic inventory, but the test could be useful as a screening device as a part of a multimethod approach that allows aggregation over measures in making diagnostic decisions.     

Differential effects of forward or simultaneous conditioned stimulus-unconditioned stimulus intervals on the defensive behavior system of the Norway rat (Rattus norvegicus)

To test several predictions derived from a behavior-systems approach, the authors assessed Pavlovian fear conditioning in rats after 30 trials of forward, simultaneous, or unpaired training. Direct evidence of conditioned fear was collected through observation of flight and freezing reactions during presentations of the conditioned stimulus (CS) alone. The authors also tested the CS's potential to reinforce an instrumental escape response in an escape-from-fear paradigm. On the one hand, rats that received forward training showed conditioned freezing, but no conditioned flight was observed. On the other hand, rats that received simultaneous training showed conditioned flight, but no conditioned freezing was observed. Rats that received either forward or simultaneous pairings showed instrumental learning of the escape-from-fear response. Implications for several theories of Pavlovian conditioning are discussed.