Do chickens (Gallus gallus f. domestica) decompose visual figures?

To investigate whether learning to discriminate between visual compound stimuli depends on decomposing them into constituting features, hens were first trained to discriminate four features (red, green, horizontal, vertical) from two dimensions (colour, line orientation). After acquisition, hens were trained with compound stimuli made up from these dimensions in two ways: a separable (line on a coloured background) stimulus and an integral one (coloured line). This compound training included a reversal of reinforcement of only one of the two dimensions (half-reversal). After having achieved the compound stimulus discrimination, a second dimensional training identical to the first was performed. Finally, in the second compound training the other dimension was reversed. Two major results were found: (1) an interaction between the dimension reversed and the type of compound stimulus: in compound training with colour reversal, separable compound stimuli were discriminated worse than integral compounds and vice versa in compound training with line orientation reversed. (2) Performance in the second compound training was worse than in the first one. The first result points to a similar mode of processing for separable and integral compounds, whereas the second result shows that the whole stimulus is psychologically superior to its constituting features. Experiment 2 repeated experiment 1 using line orientation stimuli of reversed line and background brightness. Nevertheless, the results were similar to experiment 1. Results are discussed in the framework of a configural exemplar theory of discrimination that assumes the representation of the whole stimulus situation combined with transfer based on a measure of overall similarity.     

Use of interactive voice response (IVR) technology in health research with children

This article reports on the feasibility of using interactive voice response (IVR) technology to obtain daily reports of attitudes toward alcohol and tobacco use among children 9–13 years of age. Two studies were conducted. The first was an investigation of the use of IVR technology to obtain daily data from a sample of primary school children over a period of 8 weeks. The second was an extension of the research to a large sample of primary and secondary school children in urban and rural areas who provided daily data over a 4-week period. Retention and compliance rates comparable to those obtained with adults were evident in both studies, supporting the feasibility of this technology with children. The results are discussed in relation to the benefits of this methodology for health research, particularly for studies of sensitive topics conducted with children and adolescents.     

Immediate spatial distortions of pointing movements induced by visual landmarks

We tested the influence of two horizontally aligned visual landmarks on pointing movements to memorized targets, to investigate whether the visuomotor system can make use of an egocentric representation unaffected by visual context. The endpoints of pointing movements were systematically distorted toward the nearest visual landmark, indicating that spatial representations included both target and nontarget information. These distortions were not due to the presence of the landmarks during the movement but, rather, to their presence in the encoding phase. Qualitatively similar distortions were present even with the shortest possible retention phase, when the target was extinguished at movement onset. Finally, we found the same pattern of distortion when participants were forced to remember the target within an allocentric frame of reference. We argue that even early memory representations for pointing movements are influenced by visual information in the surrounding visual field.     

Sex differences for selective forms of spatial memory

In the present study, a systematic comparison of sex differences for several tests of spatial memory was conducted. Clear evidence for more accurate male performance was obtained for precise metric positional information in a wayfinding task and in an object location memory task. In contrast, no sex difference characterized topological information processing (object-to-position assignment). Together, these findings provide further insight in the specificity of sex differences in spatial memory and in the functional architecture of spatial memory. Implications for the relevant evolutionary basis are discussed.     

Decision-making impairments in patients with Parkinson's disease

A high percentage of Parkinson's disease (PD) patients show cognitive impairments in addition to the cardinal motor symptoms. These deficits primarily concern executive functions most probably linked to dysfunctions in prefrontal regions due to decreased dopaminergic transmission in fronto-striatal loops. To investigate possible associations between decision-making and executive functions in PD, we examined 20 non-demented PD patients and 20 healthy control subjects with a neuropsychological test battery and the Game of Dice Task. In this computerised decision-making task, the rules for gains and losses and the winning probabilities are obvious and stable. Thus, strategic components besides feedback processing might influence decision-making in this task. We found that PD patients were impaired in the Game of Dice task performance and that the frequency of disadvantageous choices correlated with both executive functions and feedback processing. We suggest that decision-making deficits of PD patients in explicit gambling situations might be associated with dysfunctions in two different fronto-striatal loops: the limbic-orbitofrontal-striatal loop, involved in feedback processing, and the dorsolateral prefrontal-striatal loop, involved in executive functions.     

Lying to insurance companies: the desire to deceive among physicians and the public

This study examines the public's and physicians' willingness to support deception of insurance companies in order to obtain necessary healthcare services and how this support varies based on perceptions of physicians' time pressures. Based on surveys of 700 prospective jurors and 1617 physicians, the public was more than twice as likely as physicians to sanction deception (26%versus 11%) and half as likely to believe that physicians have adequate time to appeal coverage decisions (22%versus 59%). The odds of public support for deception compared to that of physicians rose from 2.48 to 4.64 after controlling for differences in time perception. These findings highlight the ethical challenge facing physicians and patients in balancing patient advocacy with honesty in the setting of limited societal resources.     

Countermanding saccades: evidence against independent processing of go and stop signals

In a stop signal paradigm, subjects were instructed to make a saccade to a visual target appearing left or right of the fixation point. In 25% of the trials, an auditory stop signal was presented after a variable delay that required the subject to inhibit the saccade. Observed saccadic response times in stop failure trials were longer than predicted by Logan and Cowan's (1984) race model. Saccadic response time and amplitude decreased with the time between stop signal presentation and saccade execution, suggesting an inhibitory effect between the stop signal and the go signal processes that is not compatible with an independent race assumption. Moreover, countermanding a saccade was more difficult when stop and go signals appeared at the same location.     

Anomalous induction of brightness and surface qualities: a new illusion due to radial lines and chromatic rings

When a chromatic (eg light-blue) annulus surrounds the central gap of an Ehrenstein figure so as to connect the inner ends of the radial lines, a striking new lightness effect emerges: the central white disk has both a self-luminous quality (brighter than in the regular Ehrenstein figure) and a surface quality (dense, paste-like). Self-luminous and surface qualities do not ordinarily appear co-extensively: hence, the brightness induction is called anomalous. In experiment 1, subjects separately scaled self-luminous and surface properties, and in experiment 2, brightness was nulled by physically darkening the central gap. Experiments 3 and 4 were designed to evaluate the importance of chromatic versus achromatic properties of the annulus; other aspects of the annulus (width or the inclusion of a thin black ring inside or outside the chromatic annulus) were tested in experiments 5-7. In experiments 8-12, subjects rated the brightness of modified Ehrenstein figures varying the radial lines (number, length, width, contrast, arrangement). Variation of these parameters generally affected brightness enhancement in the Ehrenstein figure and anomalous brightness induction in a similar manner, but was stronger for the latter effect. On the basis of these results, anomalous brightness induction is attributed to a surface induction process triggered by an interaction between illusory brightness enhancement (due to the radial lines) and border ownership (due to the blue annulus).     

Ethanol reduces rCFB activation of left dorsolateral prefrontal cortex during a verbal fluency task

In a previous study in normal subjects (Wendt et al., 1994), using a reversing checkerboard as activation stimulus, we found that the coupling between local neuronal activity and regional cerebral blood flow was preserved following ethanol, and that a right-sided occipital activation response seen during sobriety became symmetrical during inebriation. In the present study we investigated if ethanol has a detrimental effect also on the activation of the left dorsolateral prefrontal cortex found in normals during verbal fluency. Measurements of regional cerebral blood flow in 20 healthy, young, male, right-handed volunteers during rest and verbal fluency were made during sobriety and inebriation (0.06% blood alcohol concentration) with a 1-week interval. We found a decrease in word production during inebriation. The normal activation within the frontotemporal part of the left dorsolateral prefrontal cortext was preserved during inebriation. The activation of this region seems thus to be robust to the effects of ethanol. During inebriation no activation response to the word fluency test was found in the anterior prefrontal part of the dorsolateral prefrontal cortex. This region is important for working, temporal, and short-term memory functions, processes that are affected by ethanol. Hemispheric functioning and specialization seem to be adversely affected by ethanol, regardless of which hemisphere is most involved while sober.     

Relation of maternal responsiveness during infancy to the development of behavior problems in high-risk youths

Although problematic parenting has been consistently associated with behavior problems in youths, prospective links between early parenting and childhood behavior problems are less well established. This study examined the association of maternal responsiveness (MRes) during infancy and behavior problems in middle childhood (N = 77). MRes was significantly associated with disruptive behavior problems but was unrelated to attention problems. Absence of MRes during infancy increased the risk of disruptive behavior problems in middle childhood, even with concurrent parenting and established risk factors for disruptive behavior controlled. MRes also interacted with concurrent family risk to predict disruptive behavior symptoms. These findings underscore the importance of early parenting for developmental pathways to disruptive behavior disorders in high-risk youths. The identification of a relatively modifiable early risk factor for disruptive behavior problems has important implications for prevention.