Influence of accommodation on the viewing of an optical illusion

This study demonstrates the role of microfluctuations of accommodation in the viewing of the concentric ring illusion. Four experiments were carried out. Experiment I consisted of changing the distance between the illusion and the eyes but retaining visual angle, luminance and pupil size constant. In Experiment II, the accommodation of the eyes is paralysed by a cycloplegic. In Experiment III, the illusion is shown to a monocular aphakic and in Experiment IV, the exposure time is varied between 1/100 and 5 sec. Furthermore, a series of observations compared the concentric ring illusion seen with both eyes simultaneously. The evidence provided by the results of these experiments plus others discussed provide evidence that the concentric ring illusion is caused by the microfluctuations of accommodation.     

Sensory scaling and the psychophysical law

Sensory scaling is analysed as a sensori-motor task for which two relations must be determined, the first, S = f(I), being the relation between I, the stimulus intensity, and S, a measure of the neural effect of the stimulus, and the second being the relation between the subject's response, R, and S. It is shown that for any scaling procedure the relation between R and S can be arbitrarily specified, and according to the choice made S = f(I) will be found to be either a power function or a logarithmic function; these two “psycho- physical laws” do not reflect empirical differences between scaling procedures but conventional differences in the assumptions made when interpreting these procedures. A model is then elaborated in which S = f(I) is fixed and the relation between R and S depends on the demands of the psychophysical task and the effects of previous learning. With this more complex model the empirical implications of the power function and log function differ; it is shown that if the latter is accepted explanations can be given for two major problems in scaling theory, the disparity between the functions given by category scaling and the direct methods, and the difference between prothetic and metathetic continua.     

Health and legal issues in undercover narcotics investigations: Misrepresented evidence

This paper outlines some types of psychological disturbances found to occur in narcotics agents who use undercover investigative methods. Research results and other clinical findings dismiss popular notions of multiple personalities as a mental injury caused by prolonged role played pseudoidentities. Coping strategies for dealing with certain paranoid reactions are seen as potential sources of contamination in the gathering of evidence of criminal activity. Issues related to questions of health versus operative talents in selecting for personal suitability for undercover work are presented.     

School attainment,self-esteem,and identity: France and England

The Tajfel-Turner Theory of Social Identity was used as a framework from which it was predicted that pupils of low attainment in secondary school should come to define themselves as indifferent to or opposed to the values of their schools. This hypothesis was examined in France and England, on self-report measures covering values, aspirations, perceptions, evaluations, beliefs and motivations. While results show numerous differences between low and high attainers common to both countries, the differences are more pronounced in England. National differences are such that the French pupils are more like high attainers. Results are interpreted as being more consistent with low attaining pupils being victims of boredom rather than failure, with the French school culture providing greater insulation against such reactions.     

Orthographic vs. phonologic syllables in handwriting production

French children program the words they write syllable by syllable. We examined whether the syllable the children use to segment words is determined phonologically (i.e., is derived from speech production processes) or orthographically. Third, 4th and 5th graders wrote on a digitiser words that were mono-syllables phonologically (e.g. barque = [baRk]) but bi-syllables orthographically (e.g. barque = bar.que). These words were matched to words that were bi-syllables both phonologically and orthographically (e.g. balcon = [bal.kõ] and bal.con). The results on letter stroke duration and fluency yielded significant peaks at the syllable boundary for both types of words, indicating that the children use orthographic rather than phonological syllables as processing units to program the words they write.     

Vocabulary growth rate from preschool to school‐age years is reflected in the connectivity of the arcuate fasciculus in 14‐year‐old children

The acquisition of language involves the functional specialization of several cortical regions. Connectivity between these brain regions may also change with the development of language. Various studies have demonstrated that the arcuate fasciculus was essential for language function. Vocabulary learning is one of the most important skills in language acquisition. In the present longitudinal study, we explored the influence of vocabulary development on the anatomical properties of the arcuate fasciculus. Seventy‐nine Chinese children participated in this study. Between age 4 and age 10, they were administered the same vocabulary task repeatedly. Following a previous study, children's vocabulary developmental trajectories were clustered into three subgroups (consistently good, catch‐up, consistently poor). At age 14, diffusion tensor imaging data were collected. Using ROI‐based tractography, the anterior, posterior and direct segments of the bilateral arcuate fasciculus were delineated in each child's native space. Group comparisons showed a significantly reduced fractional anisotropy in the left arcuate fasciculus of children in the consistently poor group, in particular in the posterior and direct segments of the arcuate fasciculus. No group differences were observed in the right hemisphere, nor in the left anterior segment. Further regression analyses showed that the rate of vocabulary development, rather than the initial vocabulary size, was a specific predictor of the left arcuate fasciculus connectivity.