Contrast effects in typicality judgements: A hierarchical Bayesian approach

We examine the influence of contrast categories on the internal graded membership structure of everyday concepts using computational models proposed in the artificial category learning tradition. In particular, the generalized context model (Nosofsky, 1986), which assumes that only members of a given category contribute to the typicality of a category member, is contrasted to the similarity-dissimilarity generalized context model (SD-GCM; Stewart & Brown, 2005), which assumes that members of other categories are also influential in determining typicality. The models are compared in a hierarchical Bayesian framework in their account of the typicality gradient of five animal categories and six artefact categories. For each target category, we consider all possible relevant contrast categories. Three separate issue are examined: (a) whether contrast effects can be found, (b) which categories are responsible for these effects, and (c) whether more than one category influences the typicality. Results indicate that the internal category structure is codetermined by dissimilarity towards potential contrast categories. In most cases, only a single contrast category contributed to the typicality. The present findings suggest that contrast effects might be more widespread than has previously been assumed. Further, they stress the importance of characteristics particular of everyday concepts, which require careful consideration when applying computational models of representation of the artificial category learning tradition to everyday concepts.     

The effect of observational learning on students’ performance,processes, and motivation in two creative domains

Background . Previous research has shown that observation can be effective for learning in various domains, for example, argumentative writing and mathematics. The question in this paper is whether observational learning can also be beneficial when learning to perform creative tasks in visual and verbal arts. Aims . We hypothesized that observation has a positive effect on performance, process, and motivation. We expected similarity in competence between the model and the observer to influence the effectiveness of observation. Sample . A total of 131 Dutch students (10^th grade, 15 years old) participated. Method . Two experiments were carried out (one for visual and one for verbal arts). Participants were randomly assigned to one of three conditions; two observational learning conditions and a control condition (learning by practising). The observational learning conditions differed in instructional focus (on the weaker or the more competent model of a pair to be observed). Results . We found positive effects of observation on creative products, creative processes, and motivation in the visual domain. In the verbal domain, observation seemed to affect the creative process, but not the other variables. The model similarity hypothesis was not confirmed. Conclusions . Results suggest that observation may foster learning in creative domains, especially in the visual arts.     

Color constancy and dispositionalism

This article attempts to do two things. The first is to make it plausible that any adequate dispositional view of color will have to associate colors with complex functions from a wide range of normal circumstances to a wide range of (simultaneously) incompatible color appearances, so that there will be no uniquely veridical appearance of any given color. The second is to show that once this move is made, dispositionalism is in a position to provide interesting answers to some of the most challenging objections that have been pressed against it. It explains why colors do not seem to “come on” when the lights come on, and why the right thing to say seems to be that the light causes the objects to reveal their colors. It explains why the content of visual experience need not be problematically circular. It eliminates the problem of intrapersonal variation in color appearance. And it even provides resources for dealing with the problem of interpersonal variation. It is true that in moving to the more complex view, the dispositionalist becomes subject to a new objection, which has been called “the problem of unity.” The paper offers a solution to this problem as well.     

Receiving the Gift of Teaching: From ‘Learning From’ to ‘Being Taught By’

This paper is an enquiry into the meaning of teaching. I argue that as a result of the influence of constructivist ideas about learning on education, teaching has become increasingly understood as the facilitation of learning rather than as a process where teachers have something to give to their students. The idea that teaching is immanent to learning goes back to the Socratic idea of teaching as a maieutic process, that is, as bringing out what is already there. Against the maieutic conception of teaching I argue for an understanding of teaching in terms of transcendence, where teaching brings something radically new to the student. I explore the meaning of the idea of transcendence through a discussion of Kierkegaard and Levinas, who both criticise the maieutic understanding of teaching and, instead, argue for a transcendent understanding of teaching—an understanding of teaching which they refer to as ‘revelation.’ Whereas Kierkegaard argues that revelation—which he understand as a process of ‘double truth giving’—lies beyond the power of the teacher, Levinas interprets revelation as the experience of ‘being taught.’ I use Levinas’s suggestion in order to explore the distinction between ‘learning from’ and ‘being taught by’ and argue that teaching has to be understood in the latter sense, that is, in terms of the experience of ‘being taught.’ To connect the idea of teaching to the experience of ‘being taught’ highlights that teaching can be understood as a process of ‘truth giving’ albeit that (1) this ‘gift’ lies beyond the powers of the teacher, and (2) the truth that is given, has to be understood in terms of what Kierkegaard calls ‘subjective truth’—which is not relativistic truth but existential truth, that is, truth that matters for one’s life. Understanding teaching in these terms also opens up new possibilities for understanding the role of authority in teaching. While my argument implies that teachers cannot simply and straightforwardly ‘produce’ the experience of ‘being taught’—so that what matters has to do with the conditions under which the gift of teaching can be received—their actions and activities nonetheless matter. In the final section of the paper I therefore argue that if we want to give teaching back to education, we need to resist the depiction of the teacher as a disposable and dispensable ‘resource’ that students can learn from or not, and need to articulate and enact a different story about the teacher, the student and the school.     

Effects of anxiety on the execution of police arrest and self-defense skills

We investigated the effects of anxiety on the execution of police officers' arrest and self-defense skills. Police officers (n=13) performed three tasks in which they kicked, blocked, or restrained an opponent who attacked them with a rubber knife (low anxiety, LA) or a shock knife (high anxiety, HA) in a within-subject design. We analyzed performance (on a 5-point Likert scale), movement times, posture, and movement velocity and acceleration. Results revealed that performance was worse in the HA compared to the LA condition. Furthermore, analysis of full-body movement showed that under increased anxiety, police officers' performance contained characteristics of avoidance behavior, such as faster reactions (to reduce the time being exposed to the threat), leaning further backward (kick), and ducking down (block). In line with recent theoretical developments, it appears that under increased anxiety, police officers were less able to inhibit stimulus-driven processing (fear of getting hit) and enforce goal-directed processing (perform the skill as well as possible) leading to avoidance behavior and a decrease in performance.     

Validation of a novel cognitive bias task based on difference in quantity of reinforcement for assessing environmental enrichment

Cognitive bias tasks purport to assess affective states via responses to ambiguous stimuli. We hypothesized that a novel cognitive bias task based on positive reinforcement using quantity differences would detect changes in affect in captive grizzly bears (Ursus arctos horribilis). We trained bears (n = 8) to respond differently (nose or paw touch) to two stimuli (light or dark gray cue cards), with responses counterbalanced across bears. The two cues signaled a small or large food reward, respectively. Responses to ambiguous probe stimuli (i.e., shades of gray) intermediate to the trained stimuli were classified as either ‘optimistic,’ appropriate for the larger reward, or ‘pessimistic,’ appropriate for the smaller reward. In Experiment 1, we explored the contrast in reward size necessary to detect a change in response across probe stimuli (large reward, 3 or 6 apple slices: small reward, 1 slice). We observed a change in response across probe stimuli, with no difference in response between reward-value groups, indicating that a contrast of 3:1 apple slices was sufficient to affect responses. In Experiment 2, we investigated cognitive bias after 2.1 h of exposure to enrichment items varying in attractiveness. Results were unaffected by enrichment type or time spent interacting with enrichments, indicating that the task failed to demonstrate criterion validity for comparing mood following exposure to different enrichment items. However, greater time spent pacing prior to testing was associated with ‘optimistic’ judgments. The data provide some support for use of cognitive bias tasks based on quantity differences in animal welfare assessments involving captive wildlife.     

The (un)reliability of item-level semantic priming effects

Many researchers have tried to predict semantic priming effects using a myriad of variables (e.g., prime–target associative strength or co-occurrence frequency). The idea is that relatedness varies across prime–target pairs, which should be reflected in the size of the priming effect (e.g., cat should prime dog more than animal does). However, it is only insightful to predict item-level priming effects if they can be measured reliably. Thus, in the present study we examined the split-half and test–retest reliabilities of item-level priming effects under conditions that should discourage the use of strategies. The resulting priming effects proved extremely unreliable, and reanalyses of three published priming datasets revealed similar cases of low reliability. These results imply that previous attempts to predict semantic priming were unlikely to be successful. However, one study with an unusually large sample size yielded more favorable reliability estimates, suggesting that big data, in terms of items and participants, should be the future for semantic priming research.