Space-based visual attention models and object selection: Constraints,problems, and possible solutions

Summary One of the functions of visual attention is the selection of object information. This seems to be in line with an influential group of attentional models that assume that attentional selection is space based. These models assume that the selection of an object in vision is realized by selection of the location of that object. Whether this relatively simple idea of space-based attention and the corresponding, more elaborated space-based models are sufficient to handle selected constraints and problems of object selection is the main issue of this article. The first step toward an answer is to describe the common computational structure of space-based attentional models. Two model classes will be distinguished: capacity-limited models (e.g., Treisman, 1988; LaBerge & Brown, 1989) and models that do not assume a capacity limitation (e. g., Van der Heijden, 1992). Next, three kinds of task and data on object selection are introduced that are especially challenging for space-based models. The first type of data refers to experiments that require selection between overlapping objects. The second type of data concerns the influence of early perceptual grouping - a strong object-defining factor- on late response competition, and the third type consists of a selection task in which a high-level (semantic) attribute defines an object and controls selection. In all three cases, problems of space-based models are analyzed and possible solutions are sketched. Finally, a brief evaluative summary is given.     

Motor skill acquisition and retention as a function of average feedback, summary feedback, and performance variability

Summary feedback involves withholding feedback from subjects until the last trial in a block is completed, and then presenting feedback about each trial. A variation of this method, called average feedback (Young & Schmidt, 1992), presents subjects with only the mean of the trial block. We investigated whether these methods have similar effects on acquisition and retention of a simple motor skill. Five groups of subjects (n = 16 per group) performed 60 acquisition trials of an aiming task involving both spatial and temporal accuracy. We presented average and summary feedback based on either 5-trial blocks or 15-trial blocks and compared these schedules with every-trial feedback. During acquisition, all groups improved with practice, with a slight tendency for the every-trial condition to have less absolute error than the longer summary and average conditions. Analysis of delayed no-feedback retention tests, however, revealed a strong advantage for the 5-trial summary and average conditions compared with the every-trial condition. In addition, we found that for long blocks of acquisition trials without augmented feedback, the performance variability of those trials was associated with retention performance. Results are discussed in terms of how these different manipulations may make feedback less useful during acquisition, but foster the use of certain information processing activities that enhance overall learning.     

A revised list of Spanish translations of operant terminology

The experimental analysis of behavior has grown enormously in Latin America within the last decade. This paper offers an updating revision of suggested Spanish translations of operant expressions.     

Manual discrimination of force using active finger motion

In these experiments, two plates were grasped between the thumb and forefinger and squeezed together along a linear track. An electromechanical system presented a constant resistance force during the squeeze up to a predetermined location on the track, whereupon the force effectively went to infinity (simulating a wall) or to zero (simulating a cliff). The task of the subject was to discriminate between two alternative levels of the constant resistance force (a reference level and a reference-plus-increment level). Results of these experiments indicate a just noticeable difference of roughly 7% of the reference force using a one-interval paradigm with trial-by-trial feedback over the ranges 2.5≤F _o≤10.0 newtons, 5≤D≤30 mm, 45≤S≤125 mm, and 25≤V≤160 mm/sec, whereF _o is the reference force,D is the distance squeezed,S is the initial finger-span, andV is the mean velocity of the squeeze. These results, based on tests with 5 subjects, are consistent with a wide range of previous results, some of which are associated with other body surfaces and muscle systems and many of which were obtained with different psychophysical methods.     

Sexual experience, sex guilt, and sexual moral reasoning

Two studies are described in which the relations between sexual experience, sex guilt, and sexual moral reasoning were examined. Subjects were asked to articulate their opinions on each of six sexual activities, and then choose one of six statements (corresponding to Kohlberg's six stages of reasoning) that most clearly reflected why they had, or had not, engaged in three of those activities. An analysis of the moral reasoning present in each of the six articulated responses indicated that level of reasoning was inversely related to sex guilt. Analysis of the preference data indicated that subjects endorsed reasoning (statements) at a higher stage than they had articulated, and that this “gap” between articulation and preference was much greater for less experienced subjects. Results are discussed in terms of the utility of using situation-specific moral dilemmas when assessing moral reasoning, and in terms of the possible role that lack of sexual experience plays in inhibiting sexual moral development.     

Integrated learning communities as a peer support initiative for first year university students

Peer Mentoring schemes tend to be developed as retention strategies, however, they can also serve other purposes (psychosocial or career-related). However, evidence of the effectiveness of these presents mixed results and less is known about the horizontal peer support schemes which may help students capitalize on existing peer relationships. We developed an integrated learning communities (ILC) peer support scheme, building on the theoretical principles of social identity theory, which we embedded within our existing teaching framework and designed functional activities. Collective activities were undertaken to promote the processes of social identity with the intention that these may foster social and academic integration experiences. This intervention was undertaken with an entire cohort of first year undergraduate psychology students. We conducted semi-structured interviews with a self-selected sample of these students (N = 17). Thematic analysis revealed two main themes, each with two sub-themes. These were: “Divergent Experiences” with the sub-themes of “dependent on people” and “types of support”, and “Good idea in principle” with the sub-themes of “Theory ≠ Practice” and “Dependent on student engagement”. Although identifying with a peer group was not transparent in the interviews, the existence of a peer support scheme was perceived positively by students which might explain the success of the newly developed student-led Psychology Society. Indeed, this Psychology Society can provide a lasting framework for further amplification of the student voice. We conclude that our embedded ILC was both feasible and potentially valuable, but it is crucial for the peer support approach to have transactional significance.     

Effects of stress on nonassociative learning processes in male and female rats

In this study we assessed habituation and sensitization of the acoustic startle response (ASR) to discern whether intense, inescapable stress affects nonassociative learning differently in male and female rats. Rats were inescapably stressed 2 hours per day over 3 consecutive days. ASR magnitudes were measured at several times post-stress (1, 4, 8, and 15 days after cessation). Females generally showed greater ASR magnitudes (compared to males), but both sexes exhibited short and long-term habituation across the testing days. ASR magnitudes were only affected by stress in male subjects. The effect in males was an increase in short-term sensitization of the ASR on post-stress day-4. The results suggest that stressed males and females react differently to ASR testing, in that stress males appear to develop an exaggerated ASR response over repeated test sessions due to short-term sensitization. The source of the short-term sensitization is discussed with regards to possible stress-induced enhanced contextual learning during ASR testing on post-stress day-1.