Visual search and foraging compared in a large-scale search task

It has been argued that visual search is a valid model for human foraging. However, the two tasks differ greatly in terms of the coding of space and the effort required to search. Here we describe a direct comparison between visually guided searches (as studied in visual search tasks) and foraging that is not based upon a visually distinct target, within the same context. The experiment was conducted in a novel apparatus, where search locations were indicated by an array of lights embedded in the floor. In visually guided conditions participants searched for a target defined by the presence of a feature (red target amongst green distractors) or the absence of a feature (green target amongst red and green distractors). Despite the expanded search scale and the different response requirements, these conditions followed the pattern found in conventional visual search paradigms: feature-present search latencies were not linearly related to display size, whereas feature-absent searches were longer as the number of distractors increased. In a non-visually guided foraging condition, participants searched for a target that was only visible once the switch was activated. This resulted in far longer latencies that rose markedly with display size. Compared to eye-movements in previous visual search studies, there were few revisit errors to previously inspected locations in this condition. This demonstrates the important distinction between visually guided and non-visually guided foraging processes, and shows that the visual search paradigm is an equivocal model for general search in any context. We suggest a comprehensive model of human spatial search behaviour needs to include search at a small and large scale as well as visually guided and non-visually guided search.     

Reorientation in the real world: the development of landmark use and integration in a natural environment

An influential series of studies have argued that young children are unable to use landmark information to reorient. However, these studies have used artificial experimental environments that may lead to an underestimation of the children’s ability. We tested whether young children could reorient using landmarks in an ecologically valid setting. Children aged between 3 and 7 years completed a reorientation task in open parkland, and the properties of the search array (size and distinctiveness) were manipulated in a within-subjects design. Responses were recorded using Global Positioning Systems technology. All age groups performed above chance level, demonstrating that young children can reorient using natural landmarks. This behaviour was modulated by the nature of the search array: children were more accurate when the locations were spaced in a large array, and when the search locations were distinctively coloured. This suggests that the integration between landmarks and search locations, at different spatial scales, is a key factor in characterising human reorientation in the real world.     

WEIGHT CONSERVATION IN ZAMBIAN CHILDREN

Pour la première fois, selon L'A., L'étude de la conservation a été réalisée avec une méthode non-verbale sur des enfants de culture non-européenne. Les résultats qui ont été obtenus avec cette méthode dans un groupe contrôle d'enfants d'origine et d'éducation européennes sont comparables á ceux qui ont été trouvés en Suisse et aux Etats-Unis avec la méthode génevoise classique. On peut done s'appuyer avec une certaine confiance sur ce fait pour analyser les resultats obtenus par la méthode non-verbale avec 200 élèves d'école primaire de Zambie et les comparer aux données d'une étude australienne sur des enfants aborigènes dans laquelle la méthode classique a été utilisée. La moitié environ des enfants zambiens atteignent L'adolescence sans réussir les épreuves de conservation du poids; L'A. dégage les implications et les causes possibles d'un tel fait, et spécialement L'influence des facteurs de milieu : par exemple, la langue qui est utilisée comme véhicule d'éducation, également la qualité du matériel scolaire et de L'enseignement réel, enfin, L'effet possible de la malnutrition.     

Grounding Entails Counterpossible Non‐Triviality

This paper outlines a non‐reductive counterfactual account of grounding along interventionist lines, and uses the account to argue that taking grounding seriously requires ascribing non‐trivial truth‐conditions to a range of counterpossible counterfactuals. This result allows for a diagnosis of a route to scepticism about grounding, as deriving at least in part from scepticism about non‐trivial counterpossible truth and falsity.     

Eye remember you two: gaze direction modulates face recognition in a developmental study

The effects of gaze direction on memory for faces were studied in children from three different age groups (6-7, 8-9, and 10-11 years old) using a computerized version of a task devised by Hood, Macrae, Cole-Davies and Dias (2003). Participants were presented with a sequence of faces in an encoding phase, and were then required to judge which faces they had previously encountered in a surprise two-alternative forced-choice recognition test. In one condition, stimulus eye gaze was either direct or deviated at the viewing phase, and eyes were closed at the test phase. In another condition, stimulus eyes were closed at the viewing phase, with either direct or deviated gaze at the test phase. Modulation of gaze direction affected hit rates, with participants demonstrating greater accuracy for direct gaze targets compared to deviated gaze targets in both conditions. Reaction times (RT) to correctly recognized stimuli were faster for direct gaze stimuli at the viewing phase, but not at the test phase. The age group of participants differentially affected these measures: there was a greater hit rate advantage for direct gaze stimuli in older children, although RTs were less affected by age. These findings suggest that while the facilitation of face recognition by gaze direction is robust across encoding and recognition stages, the efficiency of the process is affected by the stage at which gaze is modulated.     

How chance explains

What explains the outcomes of chance processes? We claim that their setups do. Chances, we think, mediate these explanations of outcome by setup but do not feature in them. Facts about chances do feature in explanations of a different kind: higher-order explanations, which explain how and why setups explain their outcomes. In this paper, we elucidate this 'mediator view' of chancy explanation and defend it from a series of objections. We then show how it changes the playing field in four metaphysical disputes concerning chance. First, it makes it more plausible that even low chances can have explanatory power. Second, it undercuts a circularity objection against reductionist theories of chance. Third, it redirects the debate about a prominent argument against epistemic theories of chance. Finally, it sheds light on potential chancy explanations of the Universe's origin.     

A longitudinal exploration of the continuity of children's social participation and social withdrawal across socioeconomic status levels and social settings

The major purpose of this study was to determine the stability across time and social setting of children's social participation and social withdrawal. We followed a sample of Canadian children, aged five years at the beginning of the study, for two years. Children from lower‐SES homes were less involved than those from the higher‐SES in group play after school and during outdoor recess. Across the full sample, social withdrawal was not very stable. There was, however, considerable stability across setting and time among extreme groups of withdrawn participants. Social withdrawal was largely unrelated to parents' initiation of peer contacts for their children. Copyright © 2000 John Wiley & Sons, Ltd.