Coordination changes in the early stages of learning to cascade juggle

The experiment was setup to examine the coordination changes in assembling the movement form of 3-ball cascade juggling. Eight adult participants learned to juggle over 4 weeks of practice. Juggling scores were recorded at each session and performance was videotaped at eight selected sessions for purposes of movement analysis. Once the basic spatial and temporal constraints on cascade juggling were satisfied, and the figure-8 juggling mode was established, temporal modulations of the relative motions of the hands were emphasized. All participants learned to juggle and the increase over practice in the number of consecutive balls caught was best fit with a power law. The non-proportional rate of performance increment was consistent with the qualitative changes in the form of the hand and ball movement kinematics that occurred over practice.     

Put your money where your mouth is! Explaining collective action tendencies through group-based anger and group efficacy

Insights from appraisal theories of emotion are used to integrate elements of theories on collective action. Three experiments with disadvantaged groups systematically manipulated procedural fairness (Study 1), emotional social support (Study 2), and instrumental social support (Study 3) to examine their effects on collective action tendencies through group-based anger and group efficacy. Results of structural equation modeling showed that procedural fairness and emotional social support affected the group-based anger pathway (reflecting emotion-focused coping), whereas instrumental social support affected the group efficacy pathway (reflecting problem-focused coping), constituting 2 distinct pathways to collective action tendencies. Analyses of the means suggest that collective action tendencies become stronger the more fellow group members "put their money where their mouth is." The authors discuss how their dual pathway model integrates and extends elements of current approaches to collective action.     

Space- and object-based attention depend on motor intention

The authors investigated the impact of different motor demands on space- and object-based attention allocation. Responses to targets were either lifting a finger, or pointing to the target, or grasping a clay object placed on the target location. Reaction times and movement times were recorded to assess covert and overt attention, respectively. Both reaction times and movement times showed more space-based attention for pointing than for finger lifting and more object-based attention for grasping than for pointing. That result supports the view that visual selectivity is tuned to specific motor intentions (H. Bekkering & F. W. Neggers, 2002) and illustrates the tight coupling of perception and action.     

Illusory illusions: the significance of fixation on the perception of geometrical illusions

Some well-known geometrical illusions disappear when the eyes are fixating and saccades are suppressed for a period of time. This disappearance is not accompanied by fading due to stabilisation of the retinal image. Any saccade made on purpose restores the illusion immediately. The fixation time after which some illusions disappeared was measured for four illusions and four subjects each. Effects of practice have been observed after measurements were repeated on successive days. Present theories of vision cannot readily explain the effect.     

Hindsight bias in political elections

Two studies on political hindsight bias were conducted on the occasions of the German parliament election in 1998 and the Nordrhein-Westfalen state parliament election in 2000. In both studies, participants predicted the percentage of votes for several political parties and recalled these predictions after the election. The observed hindsight effects were stronger than those found in any prior study on political elections (using percentage of votes as the dependent variable). We argue that the length of the retention interval between original judgement and recollection is mainly responsible for this difference. In our second study, we investigated possible artifacts in political hindsight biases using a control-group design where half of the participants recalled their predictions shortly before or after the election. Hindsight bias was preserved, reinforcing the results of earlier studies with non-control-group designs. Finally, we discuss the possibility that the hindsight experience (in political judgement and in general) actually consists of three different, partly independent components.     

Time scales in motor learning and development

A theoretical framework based on the concepts and tools of nonlinear dynamical systems is advanced to account for both the persistent and transitory changes traditionally shown for the learning and development of motor skills. The multiple time scales of change in task outcome over time are interpreted as originating from the system's trajectory on an evolving attractor landscape. Different bifurcations between attractor organizations and transient phenomena can lead to exponential, power law, or S-shaped learning curves. This unified dynamical account of the functions and time scales in motor learning and development offers several new hypotheses for future research on the nature of change in learning theory.     

Promoting responsible conduct in research through “survival skills” workshops: Some mentoring is best done in a crowd

For graduate students to succeed as professionals, they must develop a set of general "survival skills". These include writing research articles, making oral presentations, obtaining employment and funding, supervising, and teaching. Traditionally, graduate programs have offered little training in many of these skills. Our educational model provides individuals with formal instruction in each area, including their ethical dimensions. Infusion of research ethics throughout a professional skills curriculum helps to emphasize that responsible conduct is integral to succeeding as a researcher. It also leads to the consideration of ethical dimensions of professional life not covered in traditional ethics courses.     

Probing spatial working memory with the Corsi Blocks task

The Corsi Blocks task (CBT) measures spatial memory span, but methodological differences across previous studies prevent a clear appreciation of perceptual, memory, and motor contributions to spatial span. CBT performance in a standard condition was compared to performance with longer encoding intervals (3 vs 1 s), longer memory intervals (9 vs 1 s), or fewer response alternatives (all nine vs only the relevant positions). All experiments also contrasted ascending vs descending order of item difficulty and recorded response-initiation times. Performance improved with longer encoding and maintenance intervals and with fewer response alternatives. Item order had no reliable effects. Response-initiation times were a useful additional measure of spatial span. Implications of these findings for research using the CBT are discussed.     

Family, personality, and social risk factors impacting the retention rates of first-year Hispanic and Anglo college students

This study investigated familial and behavioral differences between Hispanic and Anglo-American first-year college students. Analyses of variance and chi-square analyses were used to test for ethnic differences in (a) risk factors associated with family dysfunction, family addictions, personality factors, and social experiences, (b) student problem behaviors, namely alcohol use, drug use, and eating disorders, (c) a one-year follow-up of student retention, and (d) specific factors related to retention at the one-year follow-up. The Hispanic freshmen appeared to demonstrate resilience despite a lack of mentoring and greater paternal addiction. However, the one-year follow-up suggested that Hispanic females were at particular risk for leaving school. To improve college retention rates, social policy should focus on Hispanic students' vulnerabilities and strengths in making important developmental transitions.     

Viewpoint dependence in visual and haptic object recognition

On the whole, people recognize objects best when they see the objects from a familiar view and worse when they see the objects from views that were previously occluded from sight. Unexpectedly, we found haptic object recognition to be viewpoint-specific as well, even though hand movements were unrestricted. This viewpoint dependence was due to the hands preferring the back "view" of the objects. Furthermore, when the sensory modalities (visual vs. haptic) differed between learning an object and recognizing it, recognition performance was best when the objects were rotated back-to-front between learning and recognition. Our data indicate that the visual system recognizes the front view of objects best, whereas the hand recognizes objects best from the back.