How a group goal may reduce social matching in group performance: shifts in standards for determining a fair contribution of effort

The authors investigated whether the presence of a specific group goal would reduce social matching (i.e., matching one's own performance to the performance expected from others) by serving as an alternative standard. As predicted, when there was no specific goal, the participants matched their own performance to the performance expected from other group members. When there was a specific group goal, the women no longer engaged in social matching, although that effect did not emerge among the men. Instead, the women's mean personal performance was close to the performance level representing an equal share of the group goal. Moreover, the participants' perceptions of a fair contribution mediated the performance of the men and the women, both in the presence and in the absence of a goal.     

Deformation of the useful visual field with state of vigilance,task priority,and central task complexity

In a dual-task situation, peripheral perception can deteriorate due to different variables related to the experimental situation, such as central task complexity and the relative priority given to the two tasks. Recent studies have also shown that individual characteristics (such as the state of vigilance) can alter the useful visual field. The ability to perceive signals presented at different places in the visual field decreases in situations that lead to episodes of low vigilance. In Exp. 1, 27 subjects (18-29 years) had to perform a monotonous and prolonged dual-monitoring task involving central and peripheral vision. The test was carried out with two different sets of instructions regarding priority: the more important task was either the central task or the peripheral one. In Exp. 2, 18 subjects (18-30 years) performed the same test, but this time with two levels of complexity of the central task, either a simple monitoring activity or the same monitoring task coupled with a counting activity. Elliptical interpolation of the data enabled assessment of the deformation of the useful visual field in both experiments. The analysis of the parameters of the elliptical model indicated that the useful visual field mainly shrinks on the vertical axis, as the individual becomes drowsy. The useful visual field also shrinks on the horizontal axis when the peripheral task has priority and the monitoring activity is prolonged, or when the central task is complex.     

Lexical and relational influences on the processing of novel compounds

To interpret a novel compound (e.g., chocolate twig), one must access the concepts denoted by the words and select a relation that links them together. To examine the role of lexical and relation information on conceptual combination, target combinations were preceded by one of three prime combinations. In Experiment 1, the prime used a semantically similar head noun and either the same or different relation. The third prime was semantically unrelated to the target. Experiment 2 was identical, except the modifier was the semantically related constituent. Although semantic priming was observed in both experiments, relation priming was obtained only when the modifier was similar.     

Postural orientation: age-related changes in variability and time-to-boundary

The relation between age-specific postural instability and the detection of stability boundaries was examined. Balance control was investigated under different visual conditions (eyes open/closed) and postural orientations (forward/backward lean) while standing on a force platform. Dependent variables included center of pressure variability and the time-to-contact of the center of pressure with the stability boundaries around the feet (i.e., time-to-boundary). While leaning maximally, older individuals (ages 55-69) showed increased center of pressure variability compared to no lean, while younger subjects (ages 24-38) showed a decrease. These significant differences were found only in anterior-posterior direction. No significant age-specific differences were found between eyes open and eyes closed conditions. Time-to-boundary analysis revealed reduced spatio-temporal stability margins in older individuals in both anterior-posterior and medio-lateral directions. Time-to-boundary variability, however, was not significantly different between the groups in both medio-lateral and anterior-posterior direction. These results show the importance of boundary relevant center of pressure measures in the study of postural control, especially concerning the lateral instability often observed in older adults.     

Memory for multidimensional source information

Source memory may comprise recollection of multiple features of the encoding episode. To analyze the simultaneous representation and retrieval of those multiple features, a multinomial memory model is presented that measures memory for crossed dimensions of source information. The first experiment investigated the validity of the new model. The model showed an excellent statistical fit to empirical data, and the parameters of multidimensional source memory were sensitive to manipulations of source similarity on distinct dimensions. The second experiment used the model to test the hypothesis that source memory for individual context attributes is stochastically related in the case of conscious recollection but independent in the case of familiarity-based recognition judgments. The prediction was supported by the introduction of a "remember"-"know" distinction in a multidimensional source memory test.     

The Supervenience Argument and the Generalization Problem

This paper tries to show that Kims strategy of preventing the problem of generalization of mental causation is not successful and that his original supervenience argument can be applied to cases of nonmental macrolevel causation, with the effect that nonmental macroproperties which only supervene on, but are not identical with, configurations of microproperties turn out to be epiphenomenal after all.     

Global visual completion of quasi-regular shapes

The topic of amodal completion has often been investigated by using partly occluded shapes that are regular. In research that has typically been done with displays such as these regular shapes, it has been shown that global aspects of a shape can determine completion. To see how robust these global influences in the completion process are, we investigated quasi-regular shapes, ie shapes with a certain overall regularity but not based on metrical identities. First, in experiment 1 participants had to complete quasi-regular shapes in a drawing task. Then, in experiment 2 the primed-matching paradigm was used. Results from both experiments provided evidence for global completions. In experiment 3 we found that multiple global completions can be primed, which, as a control experiment showed, cannot be explained by some inability of the visual system to see the difference between the different completions. These data support the notion that global influences on visual occlusion are apparent even when the partly occluded stimulus is outside the domain of regular shapes. Implications for a global approach are provided.     

When timing the mind one should also mind the timing: biases in the measurement of voluntary actions

Trevena and Miller (2002, this issue) provide further evidence that readiness potentials occur in the brain prior to the time that participants claim to have initiated a voluntary movement, a contention originally forwarded by Libet, Gleason, Wright, and Pearl (1983). In their examination of this issue, though, aspects of their data lead them to question whether their measurement of the initiation of a voluntary movement was accurate. The current article addresses this concern by providing a direct analysis of biases in this task. This was done by asking participants to make subjective timing decisions regarding a stimulus that could be measured objectively. Our findings suggest that their timing task was indeed biased such that participants' tend to report events as happening approximately 70 ms later than they actually happened. Implications for the original Libet et al. claims are discussed.     

Physical,neural, and mental timing

The conclusions drawn by Benjamin Libet from his work with colleagues on the timing of somatosensorial conscious experiences has met with a lot of praise and criticism. In this issue we find three examples of the latter. Here I attempt to place the divide between the two opponent camps in a broader perspective by analyzing the question of the relation between physical timing, neural timing, and experiential (mental) timing. The nervous system does a sophisticated job of recombining and recoding messages from the sensorial surfaces and if these processes are slighted in a theory, it might become necessary to postulate weird operations, including subjective back-referral. Neuroscientifically inspired theories are of necessity still based on guesses, extrapolations, and philosophically dubious manners of speech. They often assume some neural correlate of consciousness (NCC) as a part of the nervous system that transforms neural activity in reportable experiences. The majority of neuroscientists appear to assume that the NCC can compare and bind activity patterns only if they arrive simultaneously at the NCC. This leads to a search for synchrony or to theories in terms of the compensation of differences in neural delays (latencies). This is the main dimension of the Libet discussion. Examples from vision research, such as "temporal-binding-by-synchrony" and the "flash-lag" effect, are then used to illustrate these reasoning patterns in more detail. Alternatively one could assume symbolic representations of time and space (symbolic "tags") that are not coded in their own dimension (not time in time and space in space). Unless such tags are multiplexed with the quality message (tickle, color, or motion), one gets a binding problem for tags. One of the hidden aspects of the discussion between Libet and opponents appears to be the following. Is the NCC smarter than the rest of the nervous system, so that it can solve the problems of local sign (e.g., "where is the event"?) and timing (e.g., "when did it occur?" and "how long did it last?") on its own, or are these pieces of information coded symbolically early on in the system? A supersmart NCC appears to be the assumption of Libet's camp (which includes Descartes, but also mystics). The wish to distribute the smartness evenly across all stages of processing in the nervous system (smart recodings) appears to motivate the opponents. I argue that there are reasons to side with the latter group.