The influence of cognitive load on spatial search performance

During search, executive function enables individuals to direct attention to potential targets, remember locations visited, and inhibit distracting information. In the present study, we investigated these executive processes in large-scale search. In our tasks, participants searched a room containing an array of illuminated locations embedded in the floor. The participants’ task was to press the switches at the illuminated locations on the floor so as to locate a target that changed color when pressed. The perceptual salience of the search locations was manipulated by having some locations flashing and some static. Participants were more likely to search at flashing locations, even when they were explicitly informed that the target was equally likely to be at any location. In large-scale search, attention was captured by the perceptual salience of the flashing lights, leading to a bias to explore these targets. Despite this failure of inhibition, participants were able to restrict returns to previously visited locations, a measure of spatial memory performance. Participants were more able to inhibit exploration to flashing locations when they were not required to remember which locations had previously been visited. A concurrent digit-span memory task further disrupted inhibition during search, as did a concurrent auditory attention task. These experiments extend a load theory of attention to large-scale search, which relies on egocentric representations of space. High cognitive load on working memory leads to increased distractor interference, providing evidence for distinct roles for the executive subprocesses of memory and inhibition during large-scale search.     

Attentional sampling of multiple wagon wheels

Attending to a periodic motion stimulus can induce illusory reversals of the direction of motion. This continuous wagon wheel illusion (c-WWI) has been taken to reflect discrete sampling of motion information by visual attention. An alternative view is that it is caused by adaptation. Here, we attempt to discriminate between these two interpretations by asking participants to attend to multiple periodic motion stimuli: The discrete attentional sampling account, but not the adaptation account, predicts a decrease of c-WWI temporal-frequency tuning with set size (with a single periodic motion stimulus the c-WWI is tuned to a temporal frequency of 10 Hz). We presented one to four rotating gratings that occasionally reversed direction while participants counted reversals. We considered reversal overestimations as manifestations of the c-WWI and determined the temporal-frequency tuning of the illusion for each set size. Optimal temporal frequency decreased with increasing set size. This outcome favors the discrete attentional sampling interpretation of the c-WWI, with a sampling rate for each individual stimulus dependent on the number of stimuli attended.     

Self and peer nominations of bullying: An analysis of incident rates,individual differences,and perceptions of the working environment

Within workplace bullying research, the use of different criteria to identify victim samples, and a tendency to rely on self-reported victimization without including reports from other stakeholders have been considered major methodological problems associated with incidence studies (Cowie, Naylor, Rivers, Smith, & Pereira, 2002; Hoel, Rayner, & Cooper, 1999; Randall, 2001). Using diverse criteria to identify victim and perpetrator samples (such as self report, peer report, and self- and peer report), this study found rates of victimization and bullying varied quite considerably. Rates for victims ranged from 3.9% to 39.6% and for perpetrators from 2.7% to 19.3%. Differences in personality and perceptions of the organizational environment were then examined between victim/bully groups and a control sample. Results indicated that all victim samples differed significantly from controls on stability. However, self- and peer-reported victims differed significantly from controls on both the poised and relaxed subscales, whereas self-reported victims only differed significantly on the relaxed subscale. Additionally, self- and peer-reported victims were the only group that significantly differed from controls in their views of the negative aspects of the work environment. The notion that victim and perpetrator samples are not homogenous groups and considerations of why this is the case are discussed.     

On the Advantages and Disadvantages of Reading Heidegger Backwards: White's Time and Death ∗

In Time and Death: Heidegger's Analysis of Finitude, Carol White pursues a strange hermeneutic strategy, reading Heidegger backwards by reading the central ideas of his later work back into his early magnum opus, Being and Time. White follows some of Heidegger's own later directives in pursuing this hermeneutic strategy, and this paper critically explores these directives along with the original reading that emerges from following them. The conclusion reached is that White's creative book is not persuasive as a strict interpretation of Heidegger's early work, but remains extremely helpful for deepening our appreciation of Heidegger's thought as a whole. Most importantly, White helps us to understand the pivotal role that thinking about death played in the lifelong development of Heidegger's philosophy.     

Eye—response lags during a continuous monitoring task

We measured the temporal relationship between eye movements and manual responses while experts and novices watched a videotaped football match. Observers used a joystick to continuously indicate the likelihood of an imminent goal. We measured correlations between manual responses and between-subjects variability in eye position. To identify the lag magnitude, we repeated these correlations over a range of possible delays between these two measures and searched for the most negative correlation coefficient. We found lags in the order of 2 sec and an effect of expertise on lag magnitude, suggesting that expertise has its effect by directing eye movements to task-relevant areas of a scene more quickly, facilitating a longer processing duration before behavioral decisions are made. This is a powerful new method for examining the eye movement behavior of multiple observers across complex moving images.     

Ethical Research in Delirium: Arguments for Including Decisionally Incapacitated Subjects

Here we describe how more important findings were obtained in a delirium study by using an informal assessment of mental capacity, and, in those who lacked capacity, obtaining consent later when or if capacity returned or a proxy was found. From a total of 233 patients 23 patients lacked capacity as judged by our informal capacity judgment and 210 did not. Of those who lacked capacity, 13 agreed to enter in the study. Six of them regained capacity later. When these 13 participants were excluded from analysis, significant findings were no longer evident. These results show that by the inclusion of subjects who lacked capacity the results of analyses of the condition from whish they suffer are altered. We suggest that this approach to the study of delirium is more ethical than the usual system of strict exclusion of people who lack capacity to give consent and for whom assent is not available.     

More about linda or conjunctions in context

Abstract

Tversky and Kahneman (1982; 1983) reported that subjects rated the con junction of two events as more likely than one of the component events. This “conjunction effect” is an error in terms of formal probability, where the probability of more happening is always smaller than the probability of less. They explained this effect in terms of a “representativeness” heuristic. This paper focuses on the context of the problem and the suggestions implied by the questions in the task. The three studies reported here provide evidence that context effects and implicit suggestions alter subjects' judgements. Tvenky and Kahneman's models take no account of such factors. Two studies show that when implicit suggestions are reduced, subjects are much less prone to the conjunction “effect”. Subjects take being asked the question “Is person X a Y?”, as providing evidence that X may be Y.     

Surface and Edge Information for Spatial Integration: A Saccadic-selection Search Task

Three experiments are described that investigate visual integration across space using a saccade selection paradigm. Subjects saccaded to a vertical target in the presence of a number of horizontal distractor items. Both horizontal and vertical items were composed of two identical elements, so, in order to locate the target, subjects had to integrate the pairs of elements together. We measured saccade accuracy, the proportion of saccades directed to the vertical target, together with saccade latency following display appearance. In Experiment 1 we found that saccade accuracy was improved by the items having either common surface properties or collinear edges. These effects were not a resultof increased display heterogeneity (Experiment 2), or a result of the introduction of a strong internal contour between the items (Experiment 3). These results show that for saccadic selection both surface and edge properties of items are processed. This in turn suggests thatearly visual processing encodes and exploits both types of information.     

Books Received

In Questioning Technology, Feenberg accuses Heidegger of an untenable 'technological essentialism'. Feenberg's criticisms are addressed not to technological essentialism as such, but rather to three particular kinds of technological essentialism: ahistoricism, substantivism, and one-dimensionalism. After these three forms of technological essentialism are explicated and Feenberg's reasons for finding them objectionable explained, the question whether Heidegger in fact subscribes to any of them is investigated. The conclusions are, first, that Heidegger's technological essentialism is not at all ahistoricist, but the opposite, an historical conception of the essence of technology which serves as the model for Feenberg's own view. Second, that while Heidegger does indeed advocate a substantivist technological essentialism, he offers a plausible, indirect response to Feenberg's voluntaristic, Marcusean objection. Third, that Heidegger's one-dimensional technological essentialism is of a non-objectionable variety, since it does not force Heidegger to reject technological devices in toto. These conclusions help vindicate Heidegger's ground-breaking ontological approach to the philosophy of technology.     

The expressibility of fragments of Hybrid Graph Logic on finite digraphs

Hybrid Graph Logic is a logic designed for reasoning about graphs and is built from a basic modal logic, augmented with the use of nominals and a facility to verify the existence of paths in graphs. We study the finite model theory of Hybrid Graph Logic. In particular, we develop pebble games for Hybrid Graph Logic and use these games to exhibit strict infinite hierarchies involving fragments of Hybrid Graph Logic when the logic is used to define problems involving finite digraphs. These fragments are parameterized by the quantifier-rank of formulae along with the numbers of propositional symbols and nominals that are available. We ascertain exactly the relative definability of these parameterized fragments of the logic.