Bridging the gap on Facebook: assessing intergroup contact and its effects for intergroup relations

In line with Allport's contact hypothesis, previous research showed that direct intergroup contact can reduce prejudices. However, establishing face-to-face contact is not always feasible. We postulate that Facebook-groups are a setting where direct and observed intergroup contact can develop, reducing prejudices and increasing mutual acceptance. Analyzing the comments of nine Facebook-groups with the destructive and constructive conflict scale, our results indicated that the expression of prejudices decreased and that of mutual acceptance increased over time, both for in- and outgroup members of the Facebook-groups. Only the expression of less prejudices, but not that of more mutual acceptance was predicted by intergroup contact. The influence of group-based motivations on the engagement in intergroup contact is discussed, and the overall findings are integrated in Steele and Brown's process model of media practices.     

Magnitude of force perception errors during static contractions of the knee extensors in healthy young and elderly individuals

The accuracy of force perception during muscular contraction has not been studied extensively, despite its importance in rehabilitation and training. The purpose of this study was to quantify the errors made by healthy young and elderly individuals in their perceptions of force produced at the knee. Four different tasks were used to evaluate the perception of force and the effect of a sensory-motor reference and simultaneous contraction on the accuracy of perception. The absolute errors were similar between groups, with values of 11.9% to 16.3%, depending on the task. The raw perception errors were greater for high levels of force (>50% of the maximal voluntary contraction, or MVC), indicating an overestimation of the forces produced for both groups. At 70% MVC, the sensory-motor reference reduced raw perception errors, and the simultaneous contraction improved the accuracy of force production. Healthy young and elderly individuals had about the same capacity to judge the muscular force of their knee extensors. Therapists involved in the training of active?elderly?individuals should be aware that the accuracy of force perception is not perfect and that these clients have the same ability as young individuals to perceive their knee extension strength.     

Implicit learning of what comes when and where within a sequence: The time-course of acquiring serial position-item and item-item associations to represent serial order

Much research has been conducted aimed at the representations and mechanisms that enable learning of sequential structures. A central debate concerns the question whether item-item associations (i.e., in the sequence A-B-C-D, B comes after A) or associations of item and serial list position (i.e., B is the second item in the list) are used to represent serial order. Previously, we showed that in a variant of the implicit serial reaction time task, the sequence representation contains associations between serial position and item information (Schuck, Gaschler, Keisler, & Frensch, 2011). Here, we applied models and research methods from working memory research to implicit serial learning to replicate and extend our findings. The experiment involved three sessions of sequence learning. Results support the view that participants acquire knowledge about order structure (item-item associations) and about ordinal structure (serial position-item associations). Analyses suggest that only the simultaneous use of the two types of knowledge acquisition can explain learning-related performance increases. Additionally, our results indicate that serial list position information plays a role very early in learning and that inter-item associations increasingly control behavior in later stages.     

Further evidence for temporal decay in working memory: reply to Lewandowsky and Oberauer (2009)

The sources of forgetting in working memory (WM) are a matter of intense debate: Is there a time-related decay of memory traces, or is forgetting uniquely due to representation-based interference? In a previous study, we claimed to have provided evidence supporting the temporal decay hypothesis (S. Portrat, P. Barrouillet, & V. Camos, 2008). However, reanalyzing our data, S. Lewandowsky and K. Oberauer (2009) demonstrated that they do not provide compelling evidence for temporal decay and suggested a class of alternative models favoring a representation-based interference account. In this article, we develop from the most recent proposals made by Lewandowsky and Oberauer 2 of the most plausible extensions of these alternative models. We show that neither of these extensions can account for recent findings related to between-domain WM performance and that both lead to predictions that are contradicted by new empirical evidence. Finally, we show that recent studies that have been claimed to rule out the temporal decay hypothesis do not resist close scrutiny. We conclude that the time-based resource-sharing model remains the most parsimonious way to account for forgetting and restoration of memory traces in WM.     

Attention and cognitive control networks assessed in a dichotic listening fMRI study

A meaningful interaction with our environment relies on the ability to focus on relevant sensory input and to ignore irrelevant information, i.e. top-down control and attention processes are employed to select from competing stimuli following internal goals. In this, the demands for the recruitment of top-down control processes depend on the relative perceptual salience of the competing stimuli. In the present functional magnetic resonance imaging (fMRI) study, we investigated the recruitment of top-down control processes in response to varying degrees of control demands in the auditory modality. For this purpose, we tested 20 male and 20 female subjects with a dichotic listening paradigm, in which the relative perceptual salience of two simultaneously presented stimuli was systematically manipulated by varying the inter-aural intensity difference (IID) and asking the subjects to selectively attend to either ear. The analysis showed that the interaction between IID and attentional direction involves two networks in the brain. A fronto-parietal network, including the pre-supplementary motor area, anterior cingulate cortex, inferior frontal junction, insula and inferior parietal lobe, was recruited during cognitively demanding conditions and can thus be seen as a top-down cognitive control network. In contrast, a second network including the superior temporal and the post-central gyri was engaged under conditions with low cognitive control demands. These findings demonstrate how cognitive control is achieved through the interplay of distinct brain networks, with their differential engagement determined as a function of the level of competition between the sensory stimuli.     

Orientation-specific aftereffects to mentally generated lines

After staring at a pattern of tilted lines, subsequent lines appear to be tilted in the opposite direction (direct tilt aftereffect, TAE). In a previous fMRI study we have demonstrated a direct TAE solely induced by the mental imagination accompanied by adaptation of orientation-selective neurons located in the extrastriate cortex, supporting the assumption of a perception-like coding of mental images. In this study we enlarge and specify the evidence for a perception-like coding of orientation-imagination. First, we replicated the previously detected direct TAE induced by line imagination with altered design-variations to control possible perceptual task confounds. Second, we tried to induce two other orientation-specific aftereffects: indirect TAE and contrast-threshold elevation aftereffect by mental imagery. The results replicate a robust direct TAE by mental imagery and by visual stimulation, with no influence of attentional resource allocation or perceptual task confounds. We could not induce an indirect TAE, but observed a perception bias in the opposite direction of the indirect TAE. The mental imagery of lines induced no orientation-selective contrast-threshold elevation aftereffect. In general, mental imagery seems to influence visual perception, indicating that perceptual resources are used by mental imagery. However, the utilisation of visual resources seems to be somewhat different from utilisation by perception.     

Motor skill learning in the middle-aged: limited development of motor chunks and explicit sequence knowledge

The present study examined whether middle-aged participants, like young adults, learn movement patterns by preparing and executing integrated sequence representations (i.e., motor chunks) that eliminate the need for external guidance of individual movements. Twenty-four middle-aged participants (aged 55–62) practiced two fixed key press sequences, one including three and one including six key presses in the discrete sequence production task. Their performance was compared with that of 24 young adults (aged 18–28). In the middle-aged participants motor chunks as well as explicit sequence knowledge appeared to be less developed than in the young adults. This held especially with respect to the unstructured 6-key sequences in which most middle-aged did not develop independence of the key-specific stimuli and learning seems to have been based on associative learning. These results are in line with the notion that sequence learning involves several mechanisms and that aging affects the relative contribution of these mechanisms.     

The extent of working memory deficits associated with Williams syndrome: exploration of verbal and spatial domains and executively controlled processes

The present study investigated verbal and spatial working memory (WM) functioning in individuals with the neuro-developmental disorder Williams syndrome (WS) using WM component tasks. While there is strong evidence of WM impairments in WS, previous research has focused on short-term memory and has neglected assessment of executive components of WM. There is a particular lack of consensus concerning the profile of verbal WM functioning in WS. Here, WS participants were compared to typically developing participants matched for (1) verbal ability and (2) spatial ability (N = 14 in each of the 3 groups). Individuals with WS were impaired on verbal WM tasks, both those involving short-term maintenance of information and executive manipulation, in comparison to verbal-matched controls. Surprisingly, individuals with WS were not impaired on a spatial task assessing short-term maintenance of information in memory (remembering spatial locations) compared to spatial-matched controls. They were, however, impaired on a spatial executive WM task requiring the manipulation of spatial information in memory. The present study suggests that individuals with WS show WM impairments that extend to both verbal and spatial domains, although spatial deficits are selective to executive aspects of WM function.     

Short-term memory performances during sustained wakefulness in patients with obstructive sleep apnea-hypopnea syndrome

Both working and immediate memories were assessed every 4h by specific short-term memory tasks over sustained wakefulness in 12 patients with obstructive sleep apnea and hypopnea syndrome (OSAHS) and 10 healthy controls. Results indicated that OSAHS patients exhibited lower working memory performances than controls on both backward digit span and complex Sternberg tasks. Speed and accuracy on Sternberg tasks were affected by memory load in both groups. However, immediate memory was not impaired in OSAHS patients. Diurnal and nocturnal SaO(2) were correlated with speed and accuracy high-speed memory scanning performance on Sternberg tasks in patients. These results suggest specific working memory deficits associated with OSAHS over sustained wakefulness with a possible deficiency in the central executive responsible for the higher information processing, in addition to a potentially insufficient storage capacity. Among OSAHS patients, working memory ability involved in high-speed memory scanning may be impaired by chronic hypoxemia.