Mechanical invariants are implicated in dynamic touch as a function of their salience in the stimulus flow.

The authors investigated the mechanical basis of length perception through dynamic touch using specially designed rods in which the various moments of mass distribution (mass, static moment, and rotational inertia) were varied independently. In a series of 4 experiments, exploration style and rod orientation were manipulated such that the relative salience of moments of mass distribution varied markedly. Results showed that perceived length was based on the most salient moments. The authors concluded that the notion of salience is crucial for understanding the implication of moments of mass distribution in length perception and that it should play a pivotal role in developing an encompassing theory of dynamic touch. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of fractality in perceptual learning: Exploration in dynamic touch.

Perceptual systems must learn to explore and to use the resulting information to hone performance. Optimal performance depends on using information available at many time scales, from the near instantaneous values of variables underlying perception (i.e., detection), to longer term information about appropriate scaling (i.e., calibration), to yet longer term information guiding variable use (i.e., attunement). Fractal fluctuations in explorations would entail fluctuation at all time scales, allowing perceptual systems a flexible way to detect information at all time scales. We tested whether perceptual learning in dynamic touch is related to the fractality of wielding behaviors. A reanalysis of wielding behaviors from Arzamarski, Isenhower, Kay, Turvey, and Michaels (2010) revealed that exploratory movements were fractal and that a fractal-scaling exponent predicts individual differences in haptic judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Which Mechanical Invariants Are Associated With the Perception of Length and Heaviness of a Nonvisible Handheld Rod? Testing the Inertia Tensor Hypothesis.

It has been suggested that the inertia tensor governs many instances of haptic perception. However, the evidence is inconclusive because other candidate mechanical parameters (i.e., invariants) were not or were insufficiently controlled for in pertinent experiments. By independently varying all candidate mechanical parameters, the authors were able to test the role of the inertia tensor relative to that of other mechanical parameters. The results showed that length perception during rod wielding is not governed by the inertia tensor alone but also by the static moment. In contrast to previous reports, length perception during rod holding and heaviness perception during rod wielding were found to be unrelated to the inertia tensor and strongly related to the static moment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The inertia tensor versus static moment and mass in perceiving length and heaviness of hand-wielded rods.

In 2 experiments, participants haptically estimated length and heaviness of handheld rods while wielding without seeing them. The sets of rods had been constructed such that variation of static moment and the 1st eigenvalue of the inertia tensor (It) were separated. Consistent with previous findings, perceived rod length correlated strongly with It. However, multiple regressions on current data as well as data from previous studies showed a comparable strong correlation between perceived rod length and static moment plus mass. Contrary to previous findings, perceived heaviness correlated strongly with static moment and only weakly with the eigenvalues of the inertia tensor. These results suggest that the inertia tensor does not provide the sole foundation for a theory of dynamic touch. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual discrimination in static and dynamic noise: The temporal relation between perceptual encoding and decision making.

The authors report 9 new experiments and reanalyze 3 published experiments that investigate factors affecting the time course of perceptual processing and its effects on subsequent decision making. Stimuli in letter-discrimination and brightness-discrimination tasks were degraded with static and dynamic noise. The onset and the time course of decision making were quantified by fitting the data with the diffusion model. Dynamic noise and, to a lesser extent, static noise, produced large shifts in the leading edge of the response-time distribution in letter discrimination but had little effect in brightness discrimination. The authors interpret these shifts as changes in the onset of decision making. The different pattern of shifts in letter discrimination and brightness discrimination implies that decision making in the 2 tasks was affected differently by noise. The changes in response-time distributions found with letter stimuli are inconsistent with the hypothesis that noise increases response times to letter stimuli simply by reducing the rate at which evidence accumulates in the decision process. Instead, they imply that noise also delays the time at which evidence accumulation begins. The delay is shown not to be the result of strategic processes or the result of using different stimuli in different tasks. The results imply, rather, that the onset of evidence accumulation in the decision process is time-locked to the perceptual encoding of the stimulus features needed to do the task. Two mechanisms that could produce this time-locking are described. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Contributions of invariants, heuristics, and exemplars to the visual perception of relative mass.

Some potential contributions of invariants, heuristics, and exemplars to the perception of dynamic properties in the colliding balls task were explored. On each trial, an observer is asked to determine the heavier of 2 colliding balls. The invariant approach assumes that people can learn to detect complex visual patterns that reliably specify which ball is heavier. The heuristic approach assumes that observers only have access to simple motion cues. The exemplar-based approach assumes that people store particular exemplars of collisions in memory, which are later retrieved to perform the task. Mathematical models of these theories are contrasted in 2 experiments. Observers may use more than 1 strategy to determine relative mass. Although observers can learn to detect and use invariants, they may rely on either heuristics before the invariant has been learned or exemplars when memory demands and similarity relations allow. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Testing a family intervention hypothesis: The contribution of mother-infant skin-to-skin contact (kangaroo care) to family interaction, proximity, and touch.

The provision of maternal-infant body contact during a period of maternal separation was examined for its effects on parent-infant and triadic interactions. Participants were 146 three-month-old preterm infants and their parents, half of whom received skin-to-skin contact, or kangaroo care (KC), in the neonatal nursery. Global relational style and micropatterns of proximity and touch were coded. Following KC, mothers and fathers were more sensitive and less intrusive, infants showed less negative affect, and family style was more cohesive. Among KC families, maternal and paternal affectionate touch of infant and spouse was more frequent, spouses remained in closer proximity, and infant proximity position was conducive to mutual gaze and touch during triadic play. The role of touch as a constituent of the co-regulatory parent-infant and triadic systems and the effects of maternal contact on mothering, co-parenting, and family processes are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress among managers: The importance of dynamic tasks, predictability, and social support in unpredictable times.

In this field study, we examined the importance of dynamic tasks as stressors faced by managers. Predictability of a task and social support by mangers’ supervisors were considered as potential moderators of the interrelation between stressors and stress effects. A total of 142 managers (64 women, 78 men) from 46 German companies took part in our study. As expected, the more tasks were perceived as dynamic, the higher was the irritation level. This correlation was significant, but low as could be expected when choosing a single predictor to explain the level of irritation. Dynamic tasks and predictability were unrelated features of the work task. Predictability of a task had a moderating effect in that the interrelation between dynamic tasks and irritation was stronger when predictability was low. When managers perceived low support from their supervisors, the interrelation between dynamic tasks and irritation was stronger as well. We were able to evaluate the specific demands of managers in a rapidly changing environment. Our results demonstrated that dynamic tasks do not necessarily lead to impaired health. Managers’ supervisors can play an important role by reflecting on how to impose change for the managers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Turning points in dynamic psychotherapy: Initial assessment, boundaries, money, disruptions and suicidal cases and The damaged core: Origins, dynamics, manifestations and treatment.

Reviews the books, Turning points in dynamic psychotherapy: Initial assessment, boundaries, money, disruptions and suicidal cases by Salman Akhtar (2009) and The damaged core: Origins, dynamics, manifestations and treatment by Salman Akhtar (2009). With these books, the author provides fresh perspectives on classic Freudian concepts and presents more modern structures with a contemporary view. In Turning points in dynamic psychotherapy Akhtar provides five situations that are inevitable in the clinical process. They are initial assessment, boundaries, money, disruption, and suicidal crises. While covering topics of ground rules, the structure of the session, and logistics within it, Akhtar simultaneously sets an interpersonal tone in his writing that seems to be parallel to the kind of interpersonal feel one would expect in the room with him. Therapeutically, tone is as important as theory. We will all do well to learn from Akhtar’s style of communication. In the second book of the volume The damaged core, Akhtar discusses a more disturbed patient. Disruptions and their repair are often the the focus of day-to-day clinical work. It is the disruptions within the dyad, not external reality reasons for disruption, that Akhtar focuses on in this volume. There is much to commend and recommend about Turning points in dynamic psychotherapy and The damaged core. Taken together, these two volumes could provide the basis for an involving seminar on the developmental etiology of relatively severe psychopathology as well as the challenges of treatment of these patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)