Predicting risk sensitivity in humans and lower animals: risk as variance or coefficient of variation

This article examines the statistical determinants of risk preference. In a meta-analysis of animal risk preference (foraging birds and insects), the coefficient of variation (CV), a measure of risk per unit of return, predicts choices far better than outcome variance, the risk measure of normative models. In a meta-analysis of human risk preference, the superiority of the CV over variance in predicting risk taking is not as strong. Two experiments show that people's risk sensitivity becomes strongly proportional to the CV when they learn about choice alternatives like other animals, by experiential sampling over time. Experience-based choices differ from choices when outcomes and probabilities are numerically described. Zipf's law as an ecological regularity and Weber's law as a psychological regularity may give rise to the CV as a measure of risk.     

Amplitude scaling in a bimanual circle-drawing task: pattern switching and end-effector variability

The authors manipulated movement amplitude in a bimanual circle-tracing task performed by 11 participants. With pacing frequency fixed, the systematic increase and decrease of circle diameter within a trial induced phase transitions from the asymmetric (33% of trials) to the symmetric bimanual circle-tracing pattern; the transitions resulted from a loss of stability in the asymmetric pattern. Tracing frequency varied inversely with circle diameter so that end-effector variability was minimized in a set of self-paced trials in which the circle diameter in a trial was fixed. In the amplitude-scaling trials, end-effector variability varied directly with circle diameter, a consistent speed-accuracy tradeoff. The results support the conclusion that movement amplitude is a nonspecific control parameter. The findings are discussed with reference to several factors, e.g., tactile feedback, the recruitment and suppression of biomechanical degrees of freedom, and the role those factors may play in stabilizing bimanual coordination patterns     

Children's understanding of television advertising: a revisit in the Chinese context

The authors conducted a survey of 1,758 elementary school children (6-14 years old) from December 2001, to March 2002, in 3 Chinese cities with different levels of television advertising. The authors used D. R. John's (1999) model of consumer socialization as the theoretical framework for their study. More than half of the children whom the authors interviewed were able to understand that television stations broadcast commercials to earn money. Their understanding of the purposes of television commercials and the persuasive intention of television commercials developed with age. The authors examined the influence of gender, level of advertising, and level of television viewing on children's understanding of television advertising by using 3-way factorial models.     

Representing others' actions: just like one's own?

Previous research has shown that observing others' actions can affect individual performance of the same actions. In the present study, we developed a new paradigm to investigate whether and how complementary actions at the disposal of another agent are represented and influence one's own actions. A spatial compatibility task was distributed among two people so that each participant took care of one of two responses. The identical task was performed alone and alongside another participant. There was a spatial compatibility effect in the group setting only. It was similar to the effect obtained when one person took care of both responses. This result suggests that one's own actions and others' actions are represented in a functionally equivalent way.     

Cortical localisation of the visual and auditory word form areas: a reconsideration of the evidence

In this paper we examine the evidence for human brain areas dedicated to visual or auditory word form processing by comparing cortical activation for auditory word repetition, reading, picture naming, and environmental sound naming. Both reading and auditory word repetition activated left lateralised regions in the frontal operculum (Broca's area), posterior superior temporal gyrus (Wernicke's area), posterior inferior temporal cortex, and a region in the mid superior temporal sulcus relative to baseline conditions that controlled for sensory input and motor output processing. In addition, auditory word repetition increased activation in a lateral region of the left mid superior temporal gyrus but critically, this area is not specific to auditory word processing, it is also activated in response to environmental sounds. There were no reading specific activations, even in the areas previously claimed as visual word form areas: activations were either common to reading and auditory word repetition or common to reading and picture naming. We conclude that there is no current evidence for cortical sites dedicated to visual or auditory word form processing.     

Evidence for preserved emotional memory in normal older persons

Emotion has been shown to have a modulatory effect on declarative memory. Normal aging is associated with a decline in declarative memory, but whether aging might affect the influence of emotion on memory has not been established. To investigate this, we administered a task that provides a detailed assessment of emotional memory to 80 neurologically normal adults ranging in age from 35 to 85 years. Across ages, memory performance was found to be modulated by the emotional significance of stimuli in a comparable manner (improved memory for gist, compromised memory for visual detail), despite an overall decline in memory performance with increasing age. The results raise the interesting possibility that aging has a differential effect on hippocampal versus amygdala function.     

Body image and self-esteem in adolescent ballet dancers.

Body-image disturbances and low self-esteem have been implicated in the pathogenesis of eating disorders. This study investigated self-perception of body and personality among adolescent ballet dancers in a cross-sectional survey. Two questionnaires assessing "my body right now" and "my personality right now," using semantic differentials were completed by 90 ballet school students and 156 controls. Adolescent female dancers (ages 13 to 17 years) scored higher than age-matched controls and 11- to 12-yr. old peers on Undesirability and Sensitivity for personality and Unattractiveness for body. For both subscales of personality, differences were also found between male and female dancers; female ballet students scored higher. Within the control group a difference could be found only for Sensitivity on which girls scored higher than boys. Male dancers did not differ from controls except for a lower score on the Body mass measure. Adolescent female dancers showed a distinct answering profile for 7 of 16 semantic differentials in each questionnaire implicating less favorable body image and self-esteem. Interventions focused particularly on enhancing self-esteem may be useful in the prevention of psychopathology in adolescent ballet dancers.     

The effects of abrupt onset of 2-D and 3-D distractors on prehension movements

This article includes two experiments aimed at investigating how two-dimensional (2-D) and three-dimensional (3-D) distractors affect the kinematics of prehension and aiming movements in order to understand the attentional processes involved in visuomotor control. In Experiment 1, subjects grasped large targets in the presence of both large and small 3-D distractors and their corresponding 2-D photographs. The distractors appeared for either 10 sec or appeared simultaneously with the target presentation. It was found that reach and grasp kinematics were influenced primarily by the small, suddenly appearing 3-D distractors. In Experiment 2, the purpose was to examine the conclusion that competition between objects (target and distractor) is related to the behavioral goal of the task. Experiment 2 is a replication of Experiment 1, with the exception that pointing movements were made instead of grasping movements. Results show that both 3-D and 2-D distractors interfered with pointing kinematics, supporting the hypothesis that attentional mechanisms are related to the goal of the task.     

Renatus renatus: the Cartesian tradition in British neuroscience and the neurophilosophy of John Carew Eccles

J. C. Eccles (1903-1997) had a highly distinguished career in neurophysiology, being awarded the Nobel Prize for Medicine or Physiology in 1963. This paper sets him within the Cartesian tradition of British neurophysiology initiated by Thomas Henry Huxley in the mid-19th century. It shows how the mind-brain problematique of the Cartesian tradition troubled him throughout his career, leading him finally to a solution in terms of quantum microphysics and microphysiology. This position, which has subsequently become fashionable, is discussed and shown (at least in the form Eccles espoused) to provide no solution to the problem posed by Descartes in the early 17th century.     

Statistical properties of the rWG(J) index of agreement

L. R. James, R. G. Demaree, and G. Wolf (1984) introduced rWG(J) to estimate interrater agreement for a group. This index is calculated by comparing an observed group variance with an expected random variance. As researchers have gained experience using this index, several questions have arisen. What are the consequences of replacing values beyond the unit interval by 0? What is the dependence of rWG(J) on the group size? The authors' simulations show that a positive bias is caused by the truncation, but for large population values of rWG(J) it is negligible. Also, in this case, the group size has no effect on the expected value of rWG(J). For inference on rWG(J), researchers can exploit the availability of computers to simulate data from the hypothesized distribution and then compare the simulation results for rWG(J) with the actual values. In addition, it is shown how the bootstrap method can be used for comparing the indices of 2 groups.