Attention and the multiple stages of multisensory integration: A review of audiovisual studies

Multisensory integration and crossmodal attention have a large impact on how we perceive the world. Therefore, it is important to know under what circumstances these processes take place and how they affect our performance. So far, no consensus has been reached on whether multisensory integration and crossmodal attention operate independently and whether they represent truly automatic processes. This review describes the constraints under which multisensory integration and crossmodal attention occur and in what brain areas these processes take place. Some studies suggest that multisensory integration and crossmodal attention take place in higher heteromodal brain areas, while others show the involvement of early sensory specific areas. Additionally, the current literature suggests that multisensory integration and attention interact depending on what processing level integration takes place. To shed light on this issue, different frameworks regarding the level at which multisensory interactions takes place are discussed. Finally, this review focuses on the question whether audiovisual interactions and crossmodal attention in particular are automatic processes. Recent studies suggest that this is not always the case. Overall, this review provides evidence for a parallel processing framework suggesting that both multisensory integration and attentional processes take place and can interact at multiple stages in the brain.     

Gaze avoidance in social phobia: Objective measure and correlates

Gaze aversion could be a central component of the physiopathology of social phobia. The emotions of the people interacting with a person with social phobia seem to model this gaze aversion. Our research consists of testing gaze aversion in subjects with social phobia compared to control subjects in different emotional faces of men and women using an eye tracker. Twenty-six subjects with DSM-IV social phobia were recruited. Twenty-four healthy subjects aged and sex-matched constituted the control group. We looked at the number of fixations and the dwell time in the eyes area on the pictures. The main findings of this research are: confirming a significantly lower amount of fixations and dwell time in patients with social phobia as a general mean and for the 6 basic emotions independently from gender; observing a significant correlation between the severity of the phobia and the degree of gaze avoidance. However, no difference in gaze avoidance according to subject/picture gender matching was observed. These findings confirm and extend some previous results, and suggest that eye avoidance is a robust marker of persons with social phobia, which could be used as a behavioral phenotype for brain imagery studies on this disorder.     

Visual working memory and threat monitoring: Spider fearfuls show disorder-specific change detection

Previous studies of biased information processing in anxiety addressed biases of attention and memory, but little is known about the processes taking place between them: visual working memory (VWM) and monitoring of threat. We investigated these processes with a change detection paradigm. In Experiment 1, spider fearfuls (SF) and non-anxious controls (NAC) judged two subsequently presented displays as same or different. The displays consisted of several pictures, one of which could depict a spider. In Experiment 2, SF and NAC, both without snake fear, were tested with displays including either a spider or a snake image to determine the material-specificity of biased VWM. Both groups showed increased change detection for threat images. This effect was significantly stronger in SF, for spider images only, indicating a threat-specific VWM bias. Thus, contrary to the assumptions made by most cognitive models of anxiety, an explicit memory bias was found.     

Looking away from death: Defensive attention as a form of terror management

Previous research has suggested that the physical aspects of human nature in general, and physical human frailties in particular become disagreeable and repugnant following death primes. The current research tested this hypothesis in two studies using an eye-tracking methodology. Participants were subliminally primed with death or with a control word and then viewed a series of arrays containing four pictures each, during which their eye-movements were monitored. In Study 1, the arrays included pictures of physical injury or neutral objects, and in Study 2 pictures of physical injury, threatening images, and neutral objects. The results indicated that in both studies death primes significantly decreased gaze duration towards pictures of physical injury, and did not have a significant effect on gaze duration towards neutral images. However, in Study 2 death primes increased gaze duration towards threatening images. The discussion examines the role of motivated unconscious attention in terror management processes.     

Structural relaxation and rejuvenation in a metallic glass induced by shot-peening

The metallic glass Pd₄₀Cu₃₀Ni₁₀P₂₀ in as-cast or pre-annealed states was shot-peened successively at room temperature or at 77 K. The structural state of the glass was characterized by the relaxation spectrum measured in a differential scanning calorimeter. Mechanically induced relaxation of the as-cast glass and mechanically induced rejuvenation of pre-annealed samples are both more evident at 77 K than at 298 K, enabling deductions about the underlying mechanisms. The relaxation spectrum of the glass as a function of temperature displays two broad maxima, which occurring at the higher temperature is attributed to the part of the free-volume distribution associated with flow defects. In samples shot-peened at 77 K, the stored energy after deformation can be as high as 20% of the cold work. Shot-peening simultaneously generates flow defects within shear bands and destroys them in the matrix between bands: whose effect dominates is principally dependent on the initial state of relaxation of the glass. Shot-peening of partially crystallized samples appears capable of breaking up and dispersing crystallites without inducing any further significant crystallization.     

Influence of properties of layered silicate minerals on adsorbed DNA surface affinity,self-assembly and nanopatterning

We report on the specific interaction between DNA and some mica-family minerals and other layered silicate structures. The interaction depends on mineral surface's crystallography, chemistry and potential. These properties are responsible for a remarkable variety of adsorption mechanisms and can be used to modulate surface self-assembly and nanopatterning of DNA. The controlled deposition of DNA onto non-conductive mineral regions with atomically flat boundaries has very attractive applications in nano-biotechnology (for example, microelectronics, microarrays and sensors). In addition, the extreme affinity discovered for some mineral surfaces, together with their ability to organize the DNA molecules, could be an indication of their catalytic potential. It may also have had relevance in the prebiotic environment, with important implications for the earth and life sciences.     

Visual perspective in autobiographical memories: Reliability,consistency, and relationship to objective memory performance

Visual perspective in autobiographical memories was examined in terms of reliability, consistency, and relationship to objective memory performance in a sample of 99 individuals. Autobiographical memories may be recalled from two visual perspectives—a field perspective in which individuals experience the memory through their own eyes, or an observer perspective in which individuals experience the memory from the viewpoint of an observer in which they can see themselves. Participants recalled nine word-cued memories that differed in emotional valence (positive, negative and neutral) and rated their memories on 18 scales. Results indicate that visual perspective was the most reliable memory characteristic overall and is consistently related to emotional intensity at the time of recall and amount of emotion experienced during the memory. Visual perspective is unrelated to memory for words, stories, abstract line drawings or faces.     

Learning to like it: Aesthetic perception of bodies,movements and choreographic structure

Appreciating human movement can be a powerful aesthetic experience. We have used apparent biological motion to investigate the aesthetic effects of three levels of movement representation: body postures, movement transitions and choreographic structure. Symmetrical (ABCDCBA) and asymmetrical (ABCDBCA) sequences of apparent movement were created from static postures, and were presented in an artificial grammar learning paradigm. Additionally, “good” continuation of apparent movements was manipulated by changing the number of movement path reversals within a sequence. In an initial exposure phase, one group of participants saw only symmetrical sequences, while another group saw only asymmetrical sequences. In a subsequent test phase, both groups rated all sequences on an aesthetic evaluation scale. We found that posture, movement, and choreographic structure all influenced aesthetic ratings. Separate ratings for the static body postures presented individually showed that both groups preferred a posture that maximized spatial symmetry. Ratings for the experimental sequences showed that both groups gave higher ratings to symmetrical sequences with “good” continuation and lower ratings to sequences with many path reversals. Further, participants who had been initially familiarized with asymmetrical sequences showed increased liking for asymmetrical sequences, suggesting a structural mere exposure effect. Aesthetic preferences thus depend on body postures, apparent movement continuation and choreographic structure. We propose a hierarchical model of aesthetic perception of human movement with distinct processing levels for body postures, movements and choreographic structure.     

Experimentally-induced dissociation impairs visual memory

Dissociation is a phenomenon common in a number of psychological disorders and has been frequently suggested to impair memory for traumatic events. In this study we explored the effects of dissociation on visual memory. A dissociative state was induced experimentally using a mirror-gazing task and its short-term effects on memory performance were investigated. Sixty healthy individuals took part in the experiment. Induced dissociation impaired visual memory performance relative to a control condition; however, the degree of dissociation was not associated with lower memory scores in the experimental group. The results have theoretical and practical implications for individuals who experience frequent dissociative states such as patients with posttraumatic stress disorder (PTSD).     

Effects of 7.5% CO2 inhalation on allocation of spatial attention to facial cues of emotional expression

Increased vigilance to threat-related stimuli is thought to be a core cognitive feature of anxiety. We sought to investigate the cognitive impact of experimentally induced anxiety, by means of a 7.5% CO₂ challenge, which acts as an unconditioned anxiogenic stimulus, on attentional bias for positive and negative facial cues of emotional expression in the dot-probe task. In two experiments we found robust physiological and subjective effects of the CO₂ inhalation consistent with the claim that the procedure reliably induces anxiety. Data from the dot-probe task demonstrated an attentional bias to emotional facial expressions compared with neutral faces regardless of valence (happy, angry, and fearful). These attentional effects, however, were entirely inconsistent in terms of their relationship with induced anxiety. We conclude that the previously reported poor reliability of this task is the most parsimonious explanation for our conflicting findings and that future research should develop a more reliable paradigm for measuring attentional bias in this field.