No abstract

Biological motion perception is referred to as the ability to recognize a moving human figure from no more than a few moving point lights. Such point-light stimuli contain limited form information about the shape of the body and local image motion signals from the moving points. The contributions of form and motion to the vivid perception of point-light displays are subject to controversy in the discussion. While some studies claim that local motion signals are critical, others emphasize the role of global form cues. Here, we present a template-matching approach to investigate the role of global form analysis. We used a template-matching method that derives biological motion exclusively from form information. The algorithm used static postures monitored from walking humans as stored templates. We compared the simulation results to psychophysical experiments with the commonly used point-light walker and a variant point-light walker with near-absent local motion signals. The common result in all experiments was a high correlation between simulation results and psychophysical data. The results show that the limited form information in point-light stimuli might be sufficient to perceive biological motion. We suggest that it is possible for humans to extract the sparse form information in point-light walkers and to use it to perceive biological motion by integrating dynamic form information over time.

Short-term saccadic adaptation is a mechanism that adjusts saccade amplitude to accurately reach an intended saccade target. Short-term saccadic adaptation induces a shift of perceived localization of objects flashed before the saccade. This shift, being detectable only before an adapted saccade, disappears at some time around saccade onset. Up to now, the exact time course of this effect has remained unknown. In previous experiments, the mislocalization caused by this adaptation-induced shift was overlapping with the mislocalization caused by a different, saccade-related localization error, the peri-saccadic compression. Due to peri-saccadic compression, objects flashed immediately at saccade onset appear compressed towards the saccade target. First, we tested whether the adaptation-induced shift and the peri-saccadic compression were either independent or related processes. We performed experiments with two different luminance-contrast conditions to separate the adaptation-induced shift and the peri-saccadic compression. Human participants had to indicate the perceived location of briefly presented stimuli before, during or after an adapted saccade. Adaptation-induced shift occurred similarly in either contrast condition, with or without peri-saccadic compression. Second, after validating the premise of both processes being independent and superimposing, we aimed at characterizing the time course of the adaptation-induced shift in more detail. Being present up to 1 s before an adapted saccade, the adaptation-induced shift begins to gradually decline from about 150 ms before saccade onset, and ceases during the saccade. A final experiment revealed that visual references make a major contribution to adaptation-induced mislocalization.

During fast, saccadic eye movements visual perception is suppressed. This saccadic suppression prevents erroneous and distracting motion percepts resulting from saccade induced retinal slip. Although saccadic suppression occurs over a substantial time interval around the saccade, there is no "perceptual gap" during saccades. The mechanisms underlying this temporal perceptual filling-in are unknown. When subjects are asked to perform temporal interval judgements of stimuli presented at the time of saccades, the time interval following the termination of the saccade appears longer than subsequent intervals of identical length. This illusion is known as "chronostasis", because a clock presented at the saccade target seemingly stops for a moment. We test whether chronostasis is a global mechanism that may compensate for the temporal gap associated with saccadic suppression. We show that a clock positioned halfway between the initial fixation point and the saccade target does not exhibit prolongation of the interval following the saccade. The characteristical distortion of temporal perception occurred only in the case of a clock being located at the saccade target. This result suggests a local, object-specific mechanism underlying the stopped clock illusion that might originate from a shift in attention immediately preceding the eye movement.

In the contextual model of teacher competence by Blömeke et al. (2015), teachers’ situation-specific skills, like perception, interpretation, and decision-making (PID-skills) are regarded as central aspects that determine the performance of teachers in a classroom and are deemed as processes that revolve around student thinking and learning (Santagata & Yeh, 2016). Teachers’ ability to notice and meet students’ needs, in turn, influences their motivation and engagement in learning. In need-supportive teaching, teachers use instructional behaviors that support students’ basic psychological needs for competence, autonomy, and relatedness. The aim of the current qualitative study was to assess student teachers’ level of PID-skills for needs supportive teaching. Due to the situative characteristics of PID-skills, authentic classroom videos were selected to assess student teachers’ noticing, analyzing and decision-making skills. After watching video clips, semi-structured interviews were carried out. Content analysis was used to discover what aspects student teachers notice; what is the level of their interpretation and decision-making. The study was conducted with 10 first-year MA-level students of several subjects teachers´ programme. The results of the study reveal that although noticing skills are of a good level, interpretation and decision-making skills can be described through lower levels, which indicate the need to pay more attention on the targeted development of student teachers PID-skills in teacher education.