Knowledge alters visual contrast sensitivity

Research has shown that the visual system’s sensitivity to variations in luminance (visual contrast) within a particular area of the retina is affected in a bottom-up fashion by the ambient contrast levels in nearby regions. Specifically, changes in the ambient contrast in areas surrounding the target area alter the sensitivity to visual contrast within the target area. More recent research has shown that paying attention to the target or target area modulates contrast sensitivity, suggesting a top-down influence over contrast sensitivity that is mediated by attention. Here we report another form of top-down influence over contrast sensitivity that is unlikely to be mediated by attention. In particular, we show that knowledge and/or expectations about the levels of visual contrast that may appear in upcoming targets also affect how sensitive the observer is to the contrast in the target. This sort of knowledge-driven, top-down contrast sensitivity control could be used to preset the visual system’s contrast sensitivity to maximize discriminability and to protect contrast-sensitive processes from a contrast overload. Overall, our results suggest that existing models of contrast sensitivity might benefit from the inclusion of top-down control mechanisms.     

Perceptual illusions in brief visual presentations

We often feel that our perceptual experience is richer than what we can express. For instance, when flashed with a large set of letters, we feel that we can see them all, while we can report only a few. However, the nature of this subjective impression remains highly debated: while many favour a dissociation between two forms of consciousness (access vs. phenomenal consciousness), others contend that the richness of phenomenal experience is a mere illusion. Here we addressed this question with a classical partial-report paradigm now modified to include unexpected items in the unreported parts of the stimuli. We show that even in the presence of unexpected pseudo-letters, participants still felt that there were only letters. Additionally, we show that this feeling reflects an illusion whereby participants reconstruct letters using partial letter-like information. We propose that the feeling of seeing emerges from the interplay between partially accessible information and expectations.     

Behavioral and neuronal attributes of short- and long-term habituation in the crab Chasmagnathus

Investigations using invertebrate species have led to a considerable progress in our understanding of the mechanisms underlying learning and memory. In this review we describe the main behavioral and neuronal findings obtained by studying the habituation of the escape response to a visual danger stimulus in the crab Chasmagnathus granulatus. Massed training with brief intertrial intervals lead to a rapid reduction of the escape response that recovers after a short term. Conversely, few trials of spaced training renders a slower escape reduction that endures for many days. As predicted by Wagner’s associative theory of habituation, long-term habituation in the crab proved to be determined by an association between the contextual environment of the training and the unconditioned stimulus. By performing intracellular recordings in the brain of the intact animal at the same time it was learning, we identified a group of neurons that remarkably reflects the short- and long-term behavioral changes. Thus, the visual memory abilities of crabs, their relatively simple and accessible nervous system, and the recording stability that can be achieved with their neurons provide an opportunity for uncovering neurophysiological and molecular events that occur in identifiable neurons during learning.     

The axiomatic method,the order of concepts and the hierarchy of sciences: an introduction

We offer an overview of some ways of examining the connections between stance and rationality, by surveying recent work on four central topics: (a) the very idea of a stance, (b) the relations between stances and voluntarism, (c) the metaphysics and epistemology that emerge once stances are brought to center stage, and (d) the role that emotions and phenomenology play in the empirical stance.     

Evaluating expectations about negative emotional states of aggressive boys using Bayesian model selection

Researchers often have expectations about the research outcomes in regard to inequality constraints between, e.g., group means. Consider the example of researchers who investigated the effects of inducing a negative emotional state in aggressive boys. It was expected that highly aggressive boys would, on average, score higher on aggressive responses toward other peers than moderately aggressive boys, who would in turn score higher than nonaggressive boys. In most cases, null hypothesis testing is used to evaluate such hypotheses. We show, however, that hypotheses formulated using inequality constraints between the group means are generally not evaluated properly. The wrong hypotheses are tested, i.e.. the null hypothesis that group means are equal. In this article, we propose an innovative solution to these above-mentioned issues using Bayesian model selection, which we illustrate using a case study.     

What Influences Work-Family Conflict? The Function of Work Support and Working from Home

The current study examined how work support resources and working from home influenced forms of work-family conflict (WFC) in employees at a large corporation. Scales measuring employee’s general WFC, time-based WFC, and strain-based WFC were used to evaluate the extent to which employees experienced work-induced conflict at home. Two forms of working at home were assessed, days worked at home and extra hours worked at home, and five variables measured the extent of one’s support resources: work social support, organizational support, individual consideration from one’s manager, idealized influence from one’s manager and contingent reward from one’s manager. We predicted that days worked at home would be negatively related to the three forms of WFC, while the extra hours worked at home would be positively related. Moreover, we hypothesized that the five support variables would moderate the relationship between extra hours worked at home and the types of WFC. The data supported some of the predictions, and the implications of these findings are discussed.     

In the Eye of the Beholder: Eye-tracking Assessment of Social Information Processing in Aggressive Behavior

Acording to social information processing theories, aggressive children are hypersensitive to cues of hostility and threat in other people’s behavior. However, even though there is ample evidence that aggressive children over-interpret others’ behaviors as hostile, it is unclear whether this hostile attribution tendency does actually result from overattending to hostile and threatening cues. Since encoding is posited to consist of rapid automatic processes, it is hard to assess with the selfreport measures that have been used so far. Therefore, we used a novel approach to investigate visual encoding of social information. The eye movements of thirty 10–13 year old children with lower levels and thirty children with higher levels of aggressive behavior were monitored in real time with an eyetracker, as the children viewed ten different cartoon series of ambiguous provocation situations. In addition, participants answered questions concerning encoding and interpretation. Aggressive children did not attend more to hostile cues, nor attend less to non-hostile cues than non-aggressive children. Contrary, aggressive children looked longer at non-hostile cues, but nonetheless attributed more hostile intent than their non-aggressive peers. These findings contradict the traditional bottom-up processing hypotheses that aggressive behavior would be related with failure to attend to non-hostile cues. The findings seem best explained by topdown information processing, where aggressive children’s pre-existing hostile intent schemata (1) direct attention towards schema inconsistent non-hostile cues, (2) prevent further processing and recall of such schema-inconsistent information, and (3) lead to hostile intent attribution and aggressive responding, disregarding the schema-inconsistent non-hostile information.     

Decreased Sensitivity to Phonemic Mismatch in Spoken Word Processing in Adult Developmental Dyslexia

Initial lexical activation in typical populations is a direct reflection of the goodness of fit between the presented stimulus and the intended target. In this study, lexical activation was investigated upon presentation of polysyllabic pseudowords (such as p rocodile for crocodile) for the atypical population of dyslexic adults to see to what extent mismatching phonemic information affects lexical activation in the face of overwhelming support for one specific lexical candidate. Results of an auditory lexical decision task showed that sensitivity to phonemic mismatch was less in the dyslexic population, compared to the respective control group. However, the dyslexic participants were outperformed by their controls only for word-initial mismatches. It is argued that a subtle speech decoding deficit affects lexical activation levels and makes spoken word processing less robust against distortion.     

Sunscreens with Titanium Dioxide (TiO<Subscript>2</Subscript>) Nano-Particles: A Societal Experiment

The risks of novel technologies, such as nano(bio)technology cannot be fully assessed due to the existing uncertainties surrounding their introduction into society. Consequently, the introduction of innovative technologies can be conceptualised as a societal experiment, which is a helpful approach to evaluate moral acceptability. This approach is illustrated with the marketing of sunscreens containing nano-sized titanium dioxide (TiO₂) particles. We argue that the marketing of this TiO₂ nanomaterial in UV protective cosmetics is ethically undesirable, since it violates four reasonable moral conditions for societal experimentation (absence of alternatives, controllability, limited informed consent, and continuing evaluation). To remedy the current way nano-sized TiO₂ containing sunscreens are utilised, we suggest five complementing actions (closing the gap, setup monitoring tools, continuing review, designing for safety, and regulative improvements) so that its marketing can become more acceptable.