Rapid categorization of foveal and extrafoveal natural images: associated ERPs and effects of lateralization

Humans are fast and accurate at performing an animal categorization task with natural photographs briefly flashed centrally. Here, this central categorization task is compared to a three position task in which photographs could appear randomly either centrally, or at 3.6 degrees eccentricity (right or left) of the fixation point. A mild behavioral impairment was found with peripheral stimuli with no evidence in support of hemispheric superiority; but enlarging the window of spatial attention to three possible stimuli locations had no behavioral cost on the processing of central images. Performance in the central categorization task has been associated with a large difference between the potentials evoked to target and non-target correct trials, starting about 150 ms after stimulus onset on frontal sites. Present results show that this activity originates within extrastriate visual cortices and probably reflects perceptual stimuli differences processed within areas involved in object recognition. Latencies, slopes, and peak amplitudes of this differential activity were invariant to stimulus position and attentional load. Stimulus location uncertainty and lateralization did not affect speed of visual processing.     

The effects of the dopamine D1 receptor antagonist SCH23390 on memory reconsolidation following reminder-activated retrieval in day-old chicks

This series of experiments examined the involvement of the dopamine D1 receptor antagonist, SCH23390, on memory reconsolidation following reminder-activated retrieval. Day-old male New HampshirexWhite Leghorn chicks were trained on a single trial passive avoidance task. A dose of 0.5 mg/kg of SCH23390 was administered subcutaneously 5 min before reminder trials, which were presented at 30, 60, and 90 min following training. Memory deficits were observed when reminder trials were presented at 30 and 60 min following training, but not when a reminder was presented at 90 min. No effect on memory retention was observed when reminder trials were not presented, suggesting that reconsolidation mechanisms were both contingent on the presentation of the reminder and independent of the consolidation process. Following a reminder presented at 60 min post-training, deficits in memory retention emerged between 45 and 60 min. The deficit was prolonged, lasting for up until 48 h after reminder presentation. The results indicate an important role for the D1 receptor in reconsolidation processes.     

Gender-typed play and amniotic testosterone

Sex differences in play are apparent in a number of mammalian species, including humans. Prenatal testosterone may contribute to these differences. The authors report the first attempt to correlate gender-typed play in a normative sample of humans with measurements of amniotic testosterone (aT). Testosterone was measured in the amniotic fluid of 53 children (31 boys and 22 girls). A strong sex difference was observed in aT and, at ages 4.75 to 5.8 years, on a modified version of the Child Game Participation Questionnaire. Hierarchical regression analyses on the entire group and within-sex correlations suggested that variations in aT did not contribute to individual differences in game participation as reported by the mother. A critique of explanations for this finding is presented.     

MATHEMATICAL EXPLANATION AND INDISPENSABILITY ARGUMENTS

We defend Joseph Melia's thesis that the role of mathematics in scientific theory is to 'index' quantities, and that even if mathematics is indispensable to scientific explanations of concrete phenomena, it does not explain any of those phenomena. This thesis is defended against objections by Mark Colyvan and Alan Baker.     

Giving hope a sporting chance: Hope as distinct from optimism when events are possible but not probable

Popular hope theories treat hope as an expectancy-based construct, with individuals more hopeful the greater their perceived likelihood of success. Consequently, the distinction between hope and other expectancy-based concepts (e.g., optimism) is unclear. The present research aims to identify the unique nature of hope, suggesting hope is invoked in particular when expectations of positive outcomes are low. As long as there is a possibility of those outcomes eventuating, individuals highly invested in them are more likely to hope; but with greater probability hope tends to align with optimism. In Study 1, for supporters of bottom-tier football teams strongly invested in the hoped-for outcome of their team winning, hope’s relationship with likelihood was cubic, accelerating with mere possibility; contrastingly, for optimism the relationship was linear. Study 2 replicated these findings for voters’ hope in state election outcomes. Hope is distinct from optimism and positive expectation; hope is tapped into when odds are low yet individuals are highly invested in the outcome.     

Virtual Selves, Real Relationships: An Exploration of the Context and Role for Social Interactions in the Emergence of Self in Virtual Environments

With the evolution of computer-mediated communication and the arrival of new virtual environments, there are potential implications for how the Self may be conceptualised. This paper considers these implications by examining the continuities and discontinuities between the Self in virtual and non-virtual environments, and contemporary and historical settings. Symbolic Interaction and Activity Theory approaches emphasise the Self as emerging in context, through Self-Other and Self-environment interactions in the minutiae of everyday life, but to some extent foreground physical rather than virtual interactions. Interactions in virtual environments are characterised by specific forms of embodiment and the experience of ??presence??, with avatars providing embodiment for interaction separate from the physical world and interaction with others being one of the determinants of presence. The complexion of Self-Other interactions in virtual environments is circumscribed by the characteristics of communications and relationships that occur in them, which are constrained by reduced social cues but overcome through the invention of techniques driven by the desire to socially interact. This paper highlights the role of symbolic mediation in the emergence of Self in virtual environments and posits that, while emergence of Self is interactive in nature, virtual environments are particular sites for a Self where the specific role of social interaction must be foregrounded.     

Genes, cognition and dyslexia: learning to read the genome

Studies of dyslexia provide vital insights into the cognitive architecture underpinning both disordered and normal reading. It is well established that inherited factors contribute to dyslexia susceptibility, but only very recently has evidence emerged to implicate specific candidate genes. In this article, we provide an accessible overview of four prominent examples--DYX1C1, KIAA0319, DCDC2 and ROBO1--and discuss their relevance for cognition. In each case correlations have been found between genetic variation and reading impairments, but precise risk variants remain elusive. Although none of these genes is specific to reading-related neuronal circuits, or even to the human brain, they have intriguing roles in neuronal migration or connectivity. Dissection of cognitive mechanisms that subserve reading will ultimately depend on an integrated approach, uniting data from genetic investigations, behavioural studies and neuroimaging.     

For efficient navigational search, humans require full physical movement, but not a rich visual scene

During navigation, humans combine visual information from their surroundings with body-based information from the translational and rotational components of their movement. Theories of navigation focus on the role of visual and rotational body-based information, even though experimental evidence shows they are not sufficient for complex spatial tasks. To investigate the contribution of all three sources of information, we asked participants to search a computer-generated virtual room for targets. Participants were provided with only visual information or with visual information supplemented with body-based information for all movement (walk group) or rotational movement (rotate group). The walk group performed the task with near-perfect efficiency, irrespective of whether a rich or impoverished visual scene was provided. The visual-only and rotate groups were significantly less efficient and frequently searched parts of the room at least twice. These results suggest that full physical movement plays a critical role in navigational search, but only moderate visual detail is required.     

The emergence of coherence over the course of decision making

Previous research has indicated that decision making is accompanied by an increase in the coherence of assessments of the factors related to the decision alternatives. In the present study, the authors investigated whether this coherence shift is obtained before people commit to a decision, and whether it is obtained in the course of a number of other processing tasks. College students were presented with a complex legal case involving multiple conflicting arguments. Participants rated agreement with the individual arguments in isolation before seeing the case and after processing it under various initial sets, including playing the role of a judge assigned to decide the case. Coherence shifts were observed when participants were instructed to delay making the decision (Experiment 1), to memorize the case (Experiment 2), and to comprehend the case (Experiment 3). The findings support the hypothesis that a coherence-generating mechanism operates in a variety of processing tasks, including decision making.