Visual temporal processing in dyslexia and the magnocellular deficit theory: the need for speed?

A controversial question in reading research is whether dyslexia is associated with impairments in the magnocellular system and, if so, how these low-level visual impairments might affect reading acquisition. This study used a novel chromatic flicker perception task to specifically explore temporal aspects of magnocellular functioning in 40 children with dyslexia and 42 age-matched controls (aged 7-11). The relationship between magnocellular temporal resolution and higher-level aspects of visual temporal processing including inspection time, single and dual-target (attentional blink) RSVP performance, go/no-go reaction time, and rapid naming was also assessed. The Dyslexia group exhibited significant deficits in magnocellular temporal resolution compared with controls, but the two groups did not differ in parvocellular temporal resolution. Despite the significant group differences, associations between magnocellular temporal resolution and reading ability were relatively weak, and links between low-level temporal resolution and reading ability did not appear specific to the magnocellular system. Factor analyses revealed that a collective Perceptual Speed factor, involving both low-level and higher-level visual temporal processing measures, accounted for unique variance in reading ability independently of phonological processing, rapid naming, and general ability.     

Self-leadership and physical vitality

The current study examined the extension of an approach to self-leadership using strategies which focus on (1) constructive thoughts, (2) natural rewards, and (3) effective behavior. The suggested extension refers to strategies which improve physical vitality, fitness, and well-being. A sample of 163 students answered scale items selected and composed to measure the four categories of self-leadership strategies. Confirmatory factor analyses and structural equation modelling indicated that strategies focusing on physical vitality, fitness, and well-being represent an independent category of self-leadership strategies. Implications for research and application were discussed.     

Different importance of the volatile and non-volatile fractions of an olfactory signature for individual social recognition in rats versus mice and short-term versus long-term memory

When tested in the olfactory cued social recognition/discrimination test, rats and mice differ in their retention of a recognition memory for a previously encountered conspecific juvenile: Rats are able to recognize a given juvenile for approximately 45 min only whereas mice show not only short-term, but also long-term recognition memory (≥ 24 h). Here we modified the social recognition/social discrimination procedure to investigate the neurobiological mechanism(s) underlying the species differences. We presented a conspecific juvenile repeatedly to the experimental subjects and monitored the investigation duration as a measure for recognition. Presentation of only the volatile fraction of the juvenile olfactory signature was sufficient for both short- and long-term recognition in mice but not rats. Applying additional volatile, mono-molecular odours to the "to be recognized" juveniles failed to affect short-term memory in both species, but interfered with long-term recognition in mice. Finally immunocytochemical analysis of c-Fos as a marker for cellular activation, revealed that juvenile exposure stimulated areas involved in the processing of olfactory signals in both the main and the accessory olfactory bulb in mice. In rats, we measured an increased c-Fos synthesis almost exclusively in cells of the accessory olfactory bulb. Our data suggest that the species difference in the retention of social recognition memory is based on differences in the processing of the volatile versus non-volatile fraction of the individuals' olfactory signature. The non-volatile fraction is sufficient for retaining a short-term social memory only. Long-term social memory - as observed in mice - requires a processing of both the volatile and non-volatile fractions of the olfactory signature.     

The relationship between acceptance,fatigue, and subjective cognitive impairment in hematologic cancer survivors

Background/Objective: Cancer and its treatment can have a detrimental impact on psychological well-being. Acceptance as the basis of acceptance and commitment therapy (ACT) has shown beneficial effects on depression and anxiety. However, its relationship to fatigue and cognitive impairment has not been investigated. A protective effect of acceptance may open up a new target for psychological intervention.Method: A cross-sectional postal survey was undertaken. 922 hematological cancer survivors (≥ 2.5 years post diagnosis) were recruited through two regional cancer registries in Germany. Acceptance (AAQ-II), fatigue (BFI) and subjective cognitive impairment (AFI) were assessed.Results: Higher levels of acceptance were negatively associated with fatigue and subjective cognitive impairment (R²= .34 and R²= .26, respectively). The relationship between fatigue and fatigue-related impairment of daily life was weaker for survivors with high acceptance.Conclusions: Acceptance is strongly associated with fatigue and subjective cognitive impairment. ACT may be useful to reduce symptoms of fatigue and subjective cognitive impairment in cancer survivors.     

Reference-related inhibition produces enhanced position discrimination and fast repulsion near axes of symmetry

Models proposed to account for reference frame effects in spatial cognition often account for performance in some tasks well, but fail to generalize to other tasks. Here, we demonstrate that a new process account of spatial working memory--the dynamic field theory (DFT)--can bridge the gap between perceptual and memory processes in position discrimination and spatial recall, highlighting that the processes underlying spatial recall also operate in position discrimination. In six experiments, we tested two novel predictions of the DFT: first, that discrimination is enhanced near symmetry axes, especially when the perceptual salience of the axis is increased; and second, that performance far from a reference axis depends on the direction in which the second stimulus is presented. The DFT also predicts the magnitude of this direction-dependent modulation. These effects arise from reference-related inhibition in the theory. We discuss how the processes captured by the DFT relate to existing psychophysical models and operate across a diverse array of spatial tasks.     

Hemispheric differences for the integration of stimulus levels and their contents: evidence from bilateral presentations

Several studies have demonstrated that hemispheric differences for the processing of hierarchical letter stimuli are more likely to occur when the letters at the levels are associated with conflicting responses. Typically, a single stimulus is presented, so that the conflict occurs between the global and the local levels of the same stimulus. Our hypothesis is that in this situation, conflict resolution requires integration of the letters and their respective levels and that the hemispheres differ in this integration process. According to this integration theory, the favorable effect of response conflict on hemispheric differences should vanish if other features, such as location, can also serve for conflict resolution. This prediction was tested in the present study by simultaneously presenting an individual hierarchical stimulus to each visual field. Conflicting letters either were arranged within one stimulus or were placed in different stimuli. In the latter case, a response conflict could also be resolved by integrating letters and locations. As was expected, there were no visual field effects in these conditions. On the other hand, visual field effects showed up when the conflicting letters were located within the same stimulus. These results support the idea that the hemispheres differ in their capacity for integrating level and form.