Relationship between implicit false belief understanding and role play: Longitudinal study

Pretend play is one of the earliest forms of children’s imagination. While social pretend play (role play) may facilitate the development of theory of mind – including false belief understanding – theoretically, the reverse may be true; theory of mind may facilitate the development of role play. To clarify this relationship, the present longitudinal study examined whether toddler’s implicit understanding of false beliefs predicted their role play during preschool years. We examined 18-month-old toddlers’ looking time in an implicit false-belief task (Time 1). When the children were 4/5 years old (Time 2), children’s parents answered a questionnaire on their child’s engagement in role play, such as playing with an imaginary companion and impersonating an imagined character. Toddlers’ looking time in the false-belief task at Time 1 predicted impersonation scores at Time 2. The results suggest that early theory of mind skills can facilitate children’s role play.     

The homogeneity effect on figure/ground perception in infancy

We examined whether the homogeneity of the two profiles of Rubin's goblet affects figure/ground perception in infants. We modified the two profiles of Rubin's goblet in order to compare figure/ground perception under four test patterns: (1) two profiles painted with horizontal lines (horizontal-line condition), (2) two profiles painted middle gray (uni-color condition), (3) one profile painted light gray and the other dark gray (two-color condition), and (4) a goblet painted with concentric circles (concentric-circles condition). In the horizontal-line condition the homogeneity of the profile was strengthened, and in the two-color condition the homogeneity of the profile was weakened compared to the uni-color condition, which was an original Rubin's goblet. In the concentric-circles condition the homogeneity of the reversed areas of the horizontal-line were strengthened.     

Transference,discrimination and reversal

A total of 68 subjects-17 normal volunteers, 17 hospitalized paranoid schizophrenics, 17 non-paranoid schizophrenics, and 17 patients with organic brain syndrome-were compared on their performance on the different phases of a specially devised conditioning procedure. This procedure is composed of (1) acquistion of the conditional reflex,i.e., squeezing a rubber bulb to the presentation of white light; (2) transference from a visual conditional stimulus to a verbal conditional stimulus and back to the visual conditional stimulus; (3) conditional stimulus differentiation; and (4) conditional stimulus reversal. Performance profiles of the normal and of the pathological groups were established and the statistically significant differences among the sub-groups of the experimental population were described. The clinical significance of these findings is discussed.     

Effects of psychoactive agents on the conditioning of the microcirculation in the rat

Normal vascular tonus and permeability of the microcirculatory network is mediated by catecholamines, histamine and serotonin. Following electroconvulsive treatment (ECT), histamine did not provoke local vasodilatation. The inhibition was further potentiated by drugs which prevent the enzymatic or physical inactivarion of free catecholamines and by locally administered norepinephrine. This system became conditioned to a visual stimulus when rats were presented in six consecutive occasions with the visual stimulus preceedingly coincided with the administration of ECT. In the conditioned rats, light alone inhibited the histamine-induced vasodilatation, and this inhibition was potentiated by sub-effective doses of injected norepinephrine and by drugs which prevent the enzymatic or physical inactivation of catecholamines. Sedatives, antidepressants, MAO inhibitors and the chlorpromazine-type agents as well as the psychotomimetic drugs characteristically influence either the acquisition or the extinction of the conditioned reflex. Results suggest that the obtained conditioning of the microcirculatory functions are mediated by tie centrally released catecholamines.     

Orienting-reflex behavior and clinical psychopathology

The effects of diagnosis, sex, age and medication on the orienting-reflex behavior of 263 psychiatric patients and 58 normal subjects were studied. Significant differences between the normal and patient groups and within the patient groups in different diagnostic categories were found. In the patient populations, further variations by types of medication received were found, whereas sex and age did not affect the orienting reflex. On the basis of frequency of response only normal subjects and patients could be distinguished, whereas amplitude analysis revealed a continuum in which the highest responses were given by normal subjects and the lowest by patients with chronic organic brain damage. In all subgroups the amplitudes of the responses of patients receiving antidepressant medication were higher than those of patients receiving antipsychotic medication.     

Behavioral evidence for format-dependent processes in approximate numerosity representation

A genuinely abstract number representation is thought to be capable of representing the numerosity of any set of discrete elements, whether they are sequentially or simultaneously presented. Recent neuroimaging studies, however, have demonstrated that different areas of intraparietal sulcus play a role in extracting numerosity across simultaneous or sequential presentation during a quantification process, suggesting the existence of a format-dependent numerical system. To test whether behavioral evidence exists for format-dependent numerical processing in adult humans, we measured the Weber fractions of numerosity discrimination for sequential stimuli, simultaneous stimuli, and cross-format stimuli with a carefully controlled experimental procedure. The results showed distinct differences between the performance in the simultaneous and sequential conditions, supporting the existence of format-dependent processes for numerosity representation. Moreover, the performance on cross-format trials differed among participants, with the exception that performance was always worse than in the simultaneous condition. Taken together, our findings suggest that numerical representation may involve a complex set of multiple stages.     

Temporal information affects the performance of numerosity discrimination: Behavioral evidence for a shared system for numerosity and temporal processing

In this study, we tested whether and how temporal information would affect the performance of numerosity discrimination in sequential events, in an attempt to make the relationship clear between temporal and numerosity processing. We manipulated the duration of event presentation (i.e., the stimulus duration) and the duration of the sequence (i.e., the total interval). We also employed three levels of standard event numbers (i.e., 5, 10, and 20) to test whether and how the effect would differ among event numbers. The results showed that temporal information affected the performance of numerosity discrimination; precision deteriorated when stimulus duration and the total interval were manipulated, and the number of events in the longer total interval were judged as less numerous than those in the shorter total interval across standard numbers. Accordingly, our results suggested the existence of a shared system between time and numerosity processing.     

An evolutionary hypothesis of suicide: why it could be biologically adaptive and is so prevalent in certain occupations

From an evolutionary perspective, suicide is a puzzle, because it has serious adverse effects, yet is remarkably common and heritable. An hypothesis is proposed to explain this puzzle, by explaining how suicide could be adaptive through reducing risk that individuals will transmit infections to kin. Empirical evidence supports four predictions from the hypothesis. There are well-established mechanisms by which infections and immune factors increase risk for mental disorders that contribute to suicide. Suicide is more prevalent in occupations with greater exposure to infection and immune-compromising factors and at higher latitudes, where key environmental factors increase vulnerability to infection. In several other highly social species, suicide-like behaviors have evolved to reduce transmission of infections. If the hypothesis is correct, detection and treatment of underlying infections and immune dysfunction should help predict and prevent suicidal behavior, while also combating spread of infectious diseases.