Mirror self-recognition beyond the face

Three studies (N=144) investigated how toddlers aged 18 and 24 months pass the surprise-mark test of self-recognition. In Study 1, toddlers were surreptitiously marked in successive conditions on their legs and faces with stickers visible only in a mirror. Rates of sticker touching did not differ significantly between conditions. In Study 2, toddlers failed to touch a sticker on their legs that had been disguised before being marked. In Study 3, having been given 30-s exposure to their disguised legs before testing, toddlers touched the stickers on their legs and faces at equivalent levels. These results suggest that toddlers pass the mark test based on expectations about what they look like, expectations that are not restricted to the face.

Neuromuscular-skeletal constraints on the acquisition of skill in a discrete torque production task

The organisation of the human neuromuscular-skeletal system allows an extremely wide variety of actions to be performed, often with great dexterity. Adaptations associated with skill acquisition occur at all levels of the neuromuscular-skeletal system although all neural adaptations are inevitably constrained by the organisation of the actuating apparatus (muscles and bones). We quantified the extent to which skill acquisition in an isometric task set is influenced by the mechanical properties of the muscles used to produce the required actions. Initial performance was greatly dependent upon the specific combination of torques required in each variant of the experimental task. Five consecutive days of practice improved the performance to a similar degree across eight actions despite differences in the torques required about the elbow and forearm. The proportional improvement in performance was also similar when the actions were performed at either 20 or 40% of participants' maximum voluntary torque capacity. The skill acquired during practice was successfully extrapolated to variants of the task requiring more torque than that required during practice. We conclude that while the extent to which skill can be acquired in isometric actions is independent of the specific combination of joint torques required for target acquisition, the nature of the kinetic adaptations leading to the performance improvement in isometric actions is influenced by the neural and mechanical properties of the actuating muscles.

Neuromuscular-skeletal origins of predominant patterns of coordination in a rhythmic two-joint arm movement

The authors tested for predominant patterns of coordination in the combination of rhythmic flexion-extension (FE) and supination-pronation (SP) at the elbow-joint complex. Participants (N = 10) spontaneously established in-phase (supination synchronized with flexion) and antiphase (pronation synchronized with flexion) patterns. In addition, the authors used a motorized robot arm to generate involuntary SP movements with different phase relations with respect to voluntary FE. The involuntarily induced in-phase pattern was accentuated and was more consistent than other patterns. That result provides evidence that the predominance of the in-phase pattern originates in the influence of neuro-muscular-skeletal constraints rather than in a preference dictated by perceptual-cognitive factors implicated in voluntary control. Neuromuscular-skeletal constraints involved in the predominance of the in-phase and the antiphase patterns are discussed.

Position information but not force information is used in adapting to changes in environmental dynamics

This study investigated how movement error is evaluated and used to change feedforward commands following a change in the environmental dynamics. In particular, we addressed the question of whether only position-error information is used or whether information about the force-field direction can also be used for rapid adaptation to changes in the environmental dynamics. Subjects learned to move in a position-dependent force field (PF) with a parabolic profile and the dynamics of a negative spring, which produced lateral force to the left of the target hand path. They adapted very rapidly, dramatically reducing lateral error after a single trial. Several times during training, the strength of the PF was unexpectedly doubled (PF2) for two trials. This again created a large leftward deviation, which was greatly reduced on the second PF2 trial, and an aftereffect when the force field subsequently returned to its original strength. The aftereffect was abolished if the second PF2 trial was replaced by an oppositely directed velocity-dependent force field (VF). During subsequent training in the VF, immediately after having adapted to the PF, subjects applied a force that assisted the force field for similar to 15 trials, indicating that they did not use information about the force-field direction. We concluded that the CNS uses only the position error for updating the internal model of the environmental dynamics and modifying feedforward commands. Although this strategy is not necessarily optimal, it may be the most reliable strategy for iterative improvement in performance.

Toddler subtraction with large sets: further evidence for an analog-magnitude representation of number

Two experiments were conducted to test the hypothesis that toddlers have access to an analog-magnitude number representation that supports numerical reasoning about relatively large numbers. Three-year-olds were presented with subtraction problems in which initial set size and proportions subtracted were systematically varied. Two sets of cookies were presented and then covered The experimenter visibly subtracted cookies from the hidden sets, and the children were asked to choose which of the resulting sets had more. In Experiment 1, performance was above chance when high proportions of objects (3 versus 6) were subtracted from large sets (of 9) and for the subset of older participants (older than 3 years, 5 months; n = 15), performance was also above chance when high proportions (10 versus 20) were subtracted from the very large sets (of 30). In Experiment 2, which was conducted exclusively with older 3-year-olds and incorporated an important methodological control, the pattern of results for the subtraction tasks was replicated In both experiments, success on the tasks was not related to counting ability. The results of these experiments support the hypothesis that young children have access to an analog-magnitude system for representing large approximate quantities, as performance on these subtraction tasks showed a Webers Law signature, and was independent of conventional number knowledge.

Understanding the multidimensionality of group development

This article presents a three-dimensional definition space of the group development literature that differentiates group development models on three dimensions: content, population, and path dependency. The multidimensional conceptualization structures and integrates the vast group development literature, enabling direct comparison of competing theories. The utility of this definition space is demonstrated by using the relative positioning of two seemingly competing group development models-the punctuated equilibrium model and the integrative model-to demonstrate their complementarity. The authors also show how organizational researchers and practitioners can use the three-dimensional definition space to select an appropriate theoretical model for the group or group process with which they are working.

Virtual reality exposure therapy: 150-degree screen to desktop PC

Virtual reality exposure therapy (VRET) developed using immersive or semi-immersive virtual environments present a usability problem for practitioners. To meet practitioner requirements for lower cost and portability VRET programs must often be ported onto desktop environments such as the personal computer (PC). However, success of VRET has been shown to be linked to presence, and the environment's ability to evoke the same reactions and emotions as a real experience. It is generally accepted that high-end virtual environments ( VEs) are more immersive than desktop PCs, but level of immersion does not always predict level of presence. This paper reports on the impact on presence of porting a therapeutic VR application for Schizophrenia from the initial research environment of a semi-immersive curved screen to PC. Presence in these two environments is measured both introspectively and across a number of causal factors thought to underlie the experience of presence. Results show that the VR exposure program successfully made users feel they were present in both platforms. While the desktop PC achieved higher scores on presence across causal factors participants reported they felt more present in the curved screen environment. While comparison of the two groups was statistically significant for the PQ but not for the IPQ, subjective reports of experiences in the environments should be considered in future research as the success of VRET relies heavily on the emotional response of patients to the therapeutic program.

When group members admit to being conformist: The role of relative intragroup status in conformity self-reports

Five studies examined the hypothesis that people will strategically portray the self as being more g-roup influenced the more junior they feel within the group. Among social psychologists (Study 1), ratings of self-conformity by g-roup members were greater when the status of the participant was low than when it was high. These effects were replicated in Studies 2, 3, and 4 in which relative intragroup status was manipulated. In Study 3, the authors found junior group members described themselves as more conformist than senior members when they were addressing an ingroup audience, but when they were addressing an outgroup audience the effect disappeared. Furthermore, junior members (but not senior members) rated themselves as more conformist when they were led to believe their responses were public than when responses were private (Study 5). The discussion focuses on the strategic processes underlying low-status group members' self-reports of group influence and the functional role of conformity in groups.

Who will see me? The impact of type of audience on willingness to display group-mediated attitude-intention consistency

The present study examined the role that group norms, group identification, and imagined audience (in-group vs. out-group) play in attitude-behavior processes. University students (N = 187) participated in a study concerned with the prediction of consumer behavior. Attitudes toward drinking their preferred beer, subjective norm, perceived behavioral control, group norm, and group identification were assessed. Intentions and perceived audience reactions to consumption were assessed. As expected, group norms, identification, and imagined audience interacted to influence likelihood of drinking one's preferred beer and perceived audience reactions. High identifiers were more responsive to group norms in the presence of an in-group audience than an out-group audience. The present results indicate that audience concerns impact upon the relationship between attitude., and behavior.

Why do people engage in collective action? Revisiting the role of perceived effectiveness

Research has shown limited support for the notion that perceived effectiveness of collective action is a predictor of intentions to engage in collective action. One reason may be that effectiveness has been in terms of whether the action will influence key decision makers. We argue that the effectiveness of collective action might be judged by other criteria, such as whether it influences third parties, builds an oppositional movement, and expresses values. Two hundred and thirty one attendees at a rally rated the effectiveness of the rally and their intentions to engage in future collective action. For those participants who were not members of an organization, intentions were linked to the perceived effectiveness of the rally in expressing values and influencing the public. For those who were members of an organization, intentions were linked only to the effectiveness of the rally in building an oppositional movement.

Get the picture? The effects of iconicity on toddlers' reenactment from picture books

What do toddlers learn from everyday picture-book reading interactions? To date, there has been scant research exploring this question. In this study, the authors adapted a standard imitation procedure to examine 18- to 30-month-olds' ability to learn how to reenact a novel action sequence from a picture book. The results provide evidence that toddlers can imitate specific target actions on novel real-world objects on the basis of a picture-book interaction. Children's imitative performance after the reading interaction varied both as a function of age and the level of iconicity of the pictures in the book. These findings are discussed in terms of children's emerging symbolic capacity and the flexibility of the cognitive representation.

Reaction time facilitation by acoustic task-irrelevant stimuli is not related to startle

Previous research has been interpreted to suggest that the startle reflex mediates the RT facilitation observed if intense, accessory acoustic stimuli are presented coinciding with the onset of a visual imperative stimulus in a forewarned simple RT task. The present research replicated this finding as well as the facilitation of startle observed during the imperative stimulus. It failed, however, to find any relationship between the size of the blink startle reflex elicited by the accessory acoustic stimuli, which differed in intensity and rise time, and RT or RT facilitation observed on trials with accessory acoustic stimuli. This finding suggests that the RT facilitation is not mediated by the startle reflex elicited by the accessory acoustic stimuli. (c) 2006 Elsevier Ireland Ltd. All rights reserved.

The new reinforcement sensitivity theory: Implications for personality measurement

In this article, we review recent modifications to Jeffrey Gray's (1973, 1991) reinforcement sensitivity theory (RST), and attempt to draw implications for psychometric measurement of personality traits. First, we consider Gray and McNaughton's (2000) functional revisions to the biobehavioral systems of RST Second, we evaluate recent clarifications relating to interdependent effects that these systems may have on behavior, in addition to or in place of separable effects (e.g., Corr 2001; Pickering, 1997). Finally, we consider ambiguities regarding the exact trait dimension to which Gray's It reward system corresponds. From this review, we suggest that future work is needed to distinguish psychometric measures of (a) fear from anxiety and (b) reward-reactivity-from trait impulsivity. We also suggest, on the basis of interdependent system views of RST and associated exploration using formal models, that traits that are based upon RST are likely to have substantial intercorrelations. Finally, we advise that more substantive work is required to define relevant constructs and behaviors in RST before we can be confident in our psychometric measures of them.

Hyperlocomotion associated with transient prenatal vitamin D deficiency is ameliorated by acute restraint

Transient prenatal vitamin D deficiency produces hyperlocomotion in the adult rat. The aim of this study was to examine the effects of acute restraint on the behaviour of DVD and control rats in the open field. Rats were conceived and born to developmentally vitamin D (DVD) deficient or replete (control) dams and, at 8 weeks of age, were monitored for 30 min in an open field using automated video tracking software. Half of the rats were restrained within a towel for 5 min immediately before the open field test. The remainder received minimal handling prior to the open field test. Repeating previous findings, DVD deficient animals had enhanced locomotion during the first 10 min of the open field test compared to control rats. By contrast, there were no differences in locomotor activity after acute restraint stress. The time rats spent in the corners and side of the open field was affected by prenatal diet. DVD rats spent less time in the corners and more time in the side than control rats across the whole 30 min test. This difference was not seen in rats with acute restraint stress. The time spent in the centre was not altered by prenatal diet or acute restraint. Thus, transient prenatal vitamin D deficiency induces a transient spontaneous hyperlocomotion in adulthood that is modulated by acute restraint stress. (c) 2006 Elsevier B.V. All rights reserved.

Spatially localized distortions of event time

A fundamental question about the perception of time is whether the neural mechanisms underlying temporal judgements are universal and centralized in the brain or modality specific and distributed []. Time perception has traditionally been thought to be entirely dissociated from spatial vision. Here we show that the apparent duration of a dynamic stimulus can be manipulated in a local region of visual space by adapting to oscillatory motion or flicker. This implicates spatially localized temporal mechanisms in duration perception. We do not see concomitant changes in the time of onset or offset of the test patterns, demonstrating a direct local effect on duration perception rather than an indirect effect on the time course of neural processing. The effects of adaptation on duration perception can also be dissociated from motion or flicker perception per se. Although 20 Hz adaptation reduces both the apparent temporal frequency and duration of a 10 Hz test stimulus, 5 Hz adaptation increases apparent temporal frequency but has little effect on duration perception. We conclude that there is a peripheral, spatially localized, essentially visual component involved in sensing the duration of visual events.