Rapid categorization of foveal and extrafoveal natural images: associated ERPs and effects of lateralization

Humans are fast and accurate at performing an animal categorization task with natural photographs briefly flashed centrally. Here, this central categorization task is compared to a three position task in which photographs could appear randomly either centrally, or at 3.6 degrees eccentricity (right or left) of the fixation point. A mild behavioral impairment was found with peripheral stimuli with no evidence in support of hemispheric superiority; but enlarging the window of spatial attention to three possible stimuli locations had no behavioral cost on the processing of central images. Performance in the central categorization task has been associated with a large difference between the potentials evoked to target and non-target correct trials, starting about 150 ms after stimulus onset on frontal sites. Present results show that this activity originates within extrastriate visual cortices and probably reflects perceptual stimuli differences processed within areas involved in object recognition. Latencies, slopes, and peak amplitudes of this differential activity were invariant to stimulus position and attentional load. Stimulus location uncertainty and lateralization did not affect speed of visual processing.     

Repeated masked category primes interfere with related exemplars: new evidence for negative semantic priming

In 4 experiments, the authors found evidence for negatively signed masked semantic priming effects (with category names as primes and exemplars as targets) using a new technique of presenting the masked primes. By rapidly interchanging prime and mask during the stimulus onset asynchrony, they increased the total prime exposure to a level comparable with that of a typical visible prime condition without increasing the number of participants having an awareness of the prime. The negative effect was observed for only low-dominance exemplars and not for high-dominance exemplars. The authors found it using lexical decision (Experiments 1 and 2), lexical decision with a response-window procedure (Experiment 3), and the pronunciation task (Experiment 4). The results are discussed with regard to different theories on semantic priming.     

Selection and consolidation of objects and actions

Response selection bottleneck models attribute performance costs under dual-task conditions to the human inability to select more than one response at a time. Consistent with this claim Pashler (1991) found that carrying out a speeded manual choice reaction time (RT) task does not impair the unspeeded report of a cued visual target from a masked display. In contrast, Jolicoeur and DellAcqua (1999, Experiment 2) observed pronounced interference between a speeded manual choice RT task and the unspeeded report of a small number of visually presented letters, a finding they attributed to resource sharing between response selection and stimulus consolidation. We demonstrate that comparable costs are obtained with the same task combination used by Pashler (1991) if only task order is reversed—a manipulation that is likely to increase the necessity of consolidating the target stimulus into working memory. We also found that these costs are not diminished if the location of the target to be reported is cued in advance (reducing demands on spatial focusing) and that they do not vary with the number of target features to be reported. These findings support a consolidation account of costs in dual-task performance.     

Remembering a location makes the eyes curve away

Working memory is a system that keeps limited information on-line for immediate access by cognitive processes. This type of active maintenance is important for everyday life activities. The present study shows that maintaining a location in spatial working memory affects the trajectories of saccadic eye movements toward visual targets, as the eyes deviate away from the remembered location. This finding provides direct evidence for a strong overlap between spatial working memory and the eye movement system. We argue that curvature is the result of the need to inhibit memory-based eye movement activity in the superior colliculus, in order to allow an accurate saccade to the visual target. Whereas previous research has shown that the eyes may deviate away from visually presented stimuli that need to be ignored, we show that the eyes also curve away from remembered stimuli.     

Reasonable Partiality and Animal Ethics

Moral psychology is often ignored in ethical theory, making applied ethics difficult to achieve in practice. This is particularly true in the new field of animal ethics. One key feature of moral psychology is recognition of the moral primacy of those with whom we enjoy relationships of love and friendship – philia in Aristotles term. Although a radically new ethic for animal treatment is emerging in society, its full expression is severely limited by our exploitative uses of animals. At this historical moment, only the animals with whom we enjoy philia – companion animals – can be treated with unrestricted moral concern. This ought to be accomplished, both for its own sake and as an ideal model for the future evolution of animal ethics.     

Recording horizontal rotations of head and eyes in spontaneous shifts,of gaze

In this paper, a method is described for simultaneous recording of horizontal rotation of the eyes in the head and rotation of the head about its natural vertical axis. Angular positions of eyesand head are obtained as proportionate dc voltages that are summed to obtain a record of the horizontal direction of gaze sensitive to l-deg saccades and accurate to within ±2 deg for at least the central 90 deg of the visual field. The apparatus is so light that it is hardly felt by the S, who, while seated, is free to move in any way he chooses and to perform any task. In addition, the angular position of a target rotating around the head may also be recorded for observation of visual-pursuit behavior.     

Further observations on overt “mediating” behavior and the discrimination of time

When the lever-pressing behavior of five rats was maintained by a DRL schedule (reinforcement was scheduled only when a specified waiting time between successive responses was exceeded), collateral behavior developed that apparently served a mediating function. In two cases this behavior did not arise until the experimental environment included pieces of wood that the rats started to nibble. When collateral behavior first appeared, it was always accompanied by an increase in responses spaced far enough apart to earn reinforcement. If collateral behavior was prevented, the number of reinforced responses always decreased. Extinction of lever pressing extinguished the collateral behavior. Adding a limited-hold contingency to the schedule did not extinguish collateral behavior. It appears that the rat can better space its responses appropriately when concurrently performing some overt collateral activity. The amount of this activity apparently comes to serve as a discriminative stimulus. To assume the existence of internal events that serve as discriminative stimuli in temporal discriminations is, at least under some circumstances, unnecessary.     

Belief,attitude and critical understanding. A systematic review of social justice in Service-Learning experiences

This systematic review examined the role of Service-Learning experiences promoted by higher education institutions to strengthen the achievement of social justice outcomes among youth. We screened and coded studies following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Of the 555 articles found in the database search, 47 peer-reviewed studies were included in the final sample. Social justice construct, together with research location, participants, target community and outcomes, were coded. Results show effects of Service-Learning experiences on (a) fostering significant improvement of students' social justice beliefs, (b) stimulating significant changes in students' attitudes with respect to the development of altruistic behaviours and their commitment to social justice, and (c) increasing students' critical understanding by sparking questioning processes related to personal assumptions of inequalities. This systematic review provides insights into the strengths and challenges of implementing social justice-oriented Service-Learning experiences.