Stable implicit motor processes despite aerobic locomotor fatigue

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. (1992). The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93-133.]. Previous work (e.g., [Masters, R. S. W. (1992). Knowledge, (k)nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343-358.]) has shown that implicitly learned motor skills remain stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. (2007). Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16(2), 456-468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system (the aerobic system), but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless (implicit) learning method or an errorful (explicit) method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber's evolutionary distinction between implicit and explicit processes.     

Easy on the mind, easy on the wallet: The roles of familiarity and processing fluency in valuation judgments

Although people routinely estimate the value of items in their environment, from goods and services to natural resources and lost earnings following an accident, the processes that underlie human valuation estimates are not well understood. We show that people use familiarity and fluency-the ease with which they process information-to determine an item's value. In three experiments, participants believed that familiar forms of currency (e.g., a familiar $1 bill) had greater purchasing power than their unfamiliar counterparts (e.g., a rare and unfamiliar coin). Mechanistic analyses showed a positive correlation between participants' familiarity with the unfamiliar currency and their estimates of its value. We conclude by discussing the theoretical and practical implications of our findings for researchers, marketing experts, and policymakers alike.     

Validation of scales from the Deployment Risk and Resilience Inventory in a sample of Operation Iraqi Freedom veterans

The Deployment Risk and Resilience Inventory (DRRI) is a suite of scales that can be used to assess deployment-related factors implicated in the health and well-being of military veterans. Although initial evidence for the reliability and validity of DRRI scales based on Gulf War veteran samples is encouraging, evidence with respect to a more contemporary cohort of Operation Iraqi Freedom (OIF) veterans is not available. Therefore, the primary goal of the present study was to validate scales from the DRRI in a large sample of OIF army personnel diversified in occupational and demographic characteristics. In general, results supported the use of these DRRI scales in this population. Internal consistency reliability estimates were quite strong. Additionally, support was obtained for criterion-related validity, as demonstrated by associations with mental and physical health measures, and discriminative validity, as demonstrated by differences between key military subgroups.     

Publication trends in behavioral gerontology in the past 25 years: are the elderly still an understudied population in behavioral research?

The case is made that issues facing the elderly are problems of social importance that should be of interest to applied behavior analysts. An electronic review of eight prominent behaviorally‐oriented journals was conducted in order to examine the frequency of publications over the past 25 years that were concerned with issues related to aging. A total of 109 articles were devoted to aging across the eight journals, with about 30% of these involving participants with cognitive impairments. Results also indicate that each of these journals has published less than one article per year related to aging. The role behavior analysts can play in serving both the elderly and their caregivers is discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Camera perspective bias in videotaped confessions: evidence that visual attention is a mediator

Several experiments have demonstrated a camera perspective bias in evaluations of videotaped confessions: videotapes with the camera focused on the suspect lead to judgments of greater voluntariness than alternative presentation formats. The present research investigated potential mediators of this bias. Using eye tracking to measure visual attention, Experiment 1 replicated the bias and revealed that changes in camera perspective are accompanied by corresponding changes in duration of fixation on the suspect and interrogator. A path analysis indicated that visual attention partially mediated the bias, with at least one additional factor independently contributing to it. A proposed second factor was changes in available visual content that naturally coincide with alterations in camera perspective. Experiment 2 directly manipulated observers' focus and thus more conclusively established visual attention as one mediator of the camera perspective bias. Together the two experiments provide plausible evidence that differences in visual content may also mediate the bias.     

Domain-specific and domain-general changes in children's development of number comparison

The numerical distance effect (inverse relationship between numerical distance and reaction time in relative number comparison tasks) has frequently been used to characterize the mental representation of number. The size of the distance effect decreases over developmental time. However, it is unclear whether this reduction simply reflects developmental changes in domain-general speed of processing and whether it is specific to numerical compared with non-numerical magnitude. To examine these open questions, we conducted a cross-sectional study with 6-, 7-, and 8-year-old children as well as adult college students. Participants performed comparisons on Arabic numerals, arrays of squares, squares of varying luminance and bars of varying height. To control for general age-related changes in reaction time, a measure of speed of processing was used as a covariate in the analysis. A significant developmental decrease in the distance effect was found across numerical and non-numerical comparison tasks over and above general changes in processing speed. However, this change was not found to differ as a function of format. These data suggest that developmental changes in the distance effect are reflective of changes in a domain-general comparison process, rather than domain-specific developmental changes in number representations. However, analysis of overall reaction times revealed significantly greater developmental changes for numerical relative to non-numerical comparison tasks. These findings highlight the importance of taking multiple measures into account when characterizing developmental changes in numerical magnitude processing. Implications for theories of numerical cognition and its development are discussed.     

Small and large number processing in infants and toddlers with Williams syndrome

Previous studies have suggested that typically developing 6‐month‐old infants are able to discriminate between small and large numerosities. However, discrimination between small numerosities in young infants is only possible when variables continuous with number (e.g. area or circumference) are confounded. In contrast, large number discrimination is successful even when variables continuous with number are systematically controlled for. These findings suggest the existence of different systems underlying small and large number processing in infancy. How do these develop in atypical syndromes? Williams syndrome (WS) is a rare neurocognitive developmental disorder in which numerical cognition has been found to be impaired in older children and adults. Do impairments of number processing have their origins in infancy? Here this question is investigated by testing the small and large number discrimination abilities of infants and toddlers with WS. While infants with WS were able to discriminate between 2 and 3 elements when total area was confounded with numerosity, the same infants did not discriminate between 8 and 16 elements, when number was not confounded with continuous variables. These findings suggest that a system for tracking the features of small numbers of object (object‐file representation) may be functional in WS, while large number discrimination is impaired from an early age onwards. Finally, we argue that individual differences in large number processing in infancy are more likely than small number processing to be predictive of later development of numerical cognition.     

Vision for perception and vision for action: normal and unusual development

Evidence suggests that visual processing is divided into the dorsal ('how') and ventral ('what') streams. We examined the normal development of these streams and their breakdown under neurological deficit by comparing performance of normally developing children and Williams syndrome individuals on two tasks: a visually guided action ('how') task, in which participants posted a card into an oriented slot, and a perception ('what') task, in which they matched a card to the slot's orientation. Results showed that all groups performed worse on the action task than the perception task, but the disparity was more pronounced in WS individuals and in normal 3-4-year-olds than in older children. These findings suggest that the 'how' system may be relatively slow to develop and more vulnerable to breakdown than the 'what' system.