Remapping versus short-term memory in visual stability across saccades

Saccadic eye movements cause displacements of the image of the visual world projected on the retina. Despite the ubiquitous nature of saccades, subjective experience of the world is continuous and stable. In five experiments, we addressed the mechanisms that may support visual stability: matching of pre- and postsaccadic locations of the target by an internal copy of the saccade, or retention of the visual attributes of the target in short-term memory across the saccade. Healthy human adults were instructed to make a saccade to a peripheral Gabor patch. While the saccade was in midflight, the patch could change location, orientation, or both. The change occurred either immediately or following a 250-ms blank during which no visual stimuli were available. In separate experiments, subjects had to report either whether the patch stepped to the left or right or whether the orientation rotated clockwise or counterclockwise. Consistent with previous findings, we found that transsaccadic displacement discrimination was enhanced by the addition of the blank. However, contrary to previous findings reported in the literature, the feature change did not improve performance. Transsaccadic orientation change discrimination did not depend on either an irrelevant temporal blank or a simultaneous irrelevant target displacement. Taken together, these findings suggest that orientation is not a relevant visual feature for transsaccadic correspondence.     

Hermeneutische und hypothetisch-deduktive Methode

Journal for General Philosophy of Science - Der Wissenschaftsbegriff kann nicht einseitig auf den Begriff von „science“ eingeengt werden. Eine strenge Scheidung in...     

Spatial interaction effects in letter processing

The hypothesis of independent processing channels was tested in a letter-recognition task. Letter space and retinal position were varied for both unilateral and bilateral presentations of two-letter configurations. The response latencies indicated contour interference effects for small letter spaces as well as a different type of processing delay which increased rapidly with increased letter distance from the fixation point. The latter effect was assumed to represent an interaction between the feature extraction processes of the adjacent letters. Since the processing capacity decreases as a function of the distance from the fovea, the reaction times were correspondingly lengthened.     

Children and situation models of multiple events

The present study demonstrates that children experience difficulties reaching the correct situation model of multiple events described in temporal sentences if the sentences encode language-external events in reverse chronological order. Importantly, the timing of the cue of how to organize these events is crucial: When temporal subordinate conjunctions (before/after) or converb constructions that carry information of how to organize the events were given sentence-medially, children experienced severe difficulties in arriving at the correct interpretation of event order. When this information was provided sentence-initially, children were better able to arrive at the correct situation model, even if it required them to decode the linguistic information reversely with respect to the actual language external events. This indicates that children even aged 8-12 still experience difficulties in arriving at the correct interpretation of the event structure, if the cue of how to order the events is not given immediately when they start building the representation of the situation. This suggests that children's difficulties in comprehending sequential temporal events are caused by their inability to revise the representation of the current event structure at the level of the situation model.     

“We” are not stressed: Social identity in groups buffers neuroendocrine stress reactions

The presence of others in threatening situations can be a mixed blessing since it is not always perceived as supportive but can also impair well-being. Building on the social identity approach, we tested the idea that the presence of others has a buffering effect on neuroendocrine stress reactions only if a sense of shared social identity is evoked. Therefore, the salience of social versus personal identity was manipulated. To induce social-evaluative stress, the Trier Social Stress Test for groups (TSST-G) was employed, while in the control conditions the Placebo-TSST-G was used. As predicted, social identity salience attenuated the stress-induced cortisol reaction in the TSST-G condition. By contrast, there was no effect of identity salience in the Placebo-TSST-G conditions. These findings provide the first experimental evidence for the idea that being part of a group buffers neuroendocrine stress only if group members develop a sense of shared social identity.     

Motor coordination dynamics underlying graphic motion in 7- to 11-year-old children

Using concepts and tools of a dynamical system approach in order to understand motor coordination underlying graphomotor skills, the aim of the current study was to establish whether the basic coordination dynamics found in adults is already established in children at elementary school, when handwriting is trained and eventually acquired. In the study, 45 children and 9 adults volunteered to copy two series of 13 ellipsoid shapes. These shapes were generated by manipulating the relative phase between 0° and 180° of two orthogonal oscillators in two orientations. Findings showed that although children from an early age onward and adults reproduced straight lines precisely (i.e., 0° and 180°), the former drew ellipsoid shapes in a less eccentric fashion than the latter (i.e., ～90° in all children rather than ～60° and 120° in adults). This tendency to write in a rounder fashion persists until 11 years of age, suggesting that the coordination dynamics underlying graphomotor skills and tentatively shaping the coordinated activity involved in adult handwriting appears only later, probably due to increasing constraints on speed.     

Memory aging and brain maintenance

Episodic memory and working memory decline with advancing age. Nevertheless, large-scale population-based studies document well-preserved memory functioning in some older individuals. The influential ‘reserve’ notion holds that individual differences in brain characteristics or in the manner people process tasks allow some individuals to cope better than others with brain pathology and hence show preserved memory performance. Here, we discuss a complementary concept, that of brain maintenance (or relative lack of brain pathology), and argue that it constitutes the primary determinant of successful memory aging. We discuss evidence for brain maintenance at different levels: cellular, neurochemical, gray- and white-matter integrity, and systems-level activation patterns. Various genetic and lifestyle factors support brain maintenance in aging and interventions may be designed to promote maintenance of brain structure and function in late life.