ATC-lab: An air traffic control simulator for the laboratory

Air Traffic Control Laboratory Simulator (ATC-lab) is a new low- and medium-fidelity task environment that simulates air traffic control. ATC-lab allows the researcher to study human performance of tasks under tightly controlled experimental conditions in a dynamic, spatial environment. The researcher can create standardized air traffic scenarios by manipulating a wide variety of parameters. These include temporal and spatial variables. There are two main versions of ATC-lab. The medium-fidelity simulator provides a simplified version of en route air traffic control, requiring participants to visually search a screen and both recognize and resolve conflicts so that adequate separation is maintained between all aircraft. The low-fidelity simulator presents pairs of aircraft in isolation, controlling the participant’s focus of attention, which provides a more systematic measurement of conflict recognition and resolution performance. Preliminary studies have demonstrated that ATC-lab is a flexible tool for applied cognition research.     

Cross-dimensional interference and cross-trial inhibition

In two experiments, we examined whether one source of cross-dimensional interference in visual search involves cross-trial position priming. In Experiment 1, we demonstrated cross-dimensional interference in search for an orientation-defined target: Search for a left-tilted target among right-tilted non-targets was disrupted by the presence of a singleton color distractor. In all conditions, search was facilitated when a target was presented at the same position as a target in the previous trial (positive position priming). In addition, there were negative effects of position priming on orientation targets that fell on the same side as singleton distractors on the previous trial. In Experiment 2, to examine the impact of negative position priming on cross-dimensional interference, trials with and without singleton distractors were presented in a single trial block. The chance of a singleton distractor's being present on a preceding trial was then equated across displays when the distractor was and when it was not subsequently present. Cross-dimensional interference was eliminated under this mixed presentation condition, suggesting that the cost of cross-dimensional interference was not determined by the stimulus-driven factors in the current trial, at least when a limited number of target and distractor locations was used. We conclude that top-down selection is possible during visual search, and this leads to inhibition of the location of salient distractors. The cost of this is slowed detection of targets at inhibited locations on subsequent trials.     

The combined effects of plane disorientation and foreshortening on picture naming: one manipulation or two?

Objects disoriented in plane away from the upright and objects rotated in depth producing foreshortening are harder to identify than canonical views. In Experiments 1 and 2, participants named pictures of familiar objects. There was no interaction between plane and depth rotation effects on initial presentation or after practice. Experiment 3 was a dual-task psychological refractory period study. Participants classified a high-low tone with a speeded keypress and then named a canonical, plane-rotated, or foreshortened view of an object. Naming was slower when the picture was presented 50 ms after the tone compared with 800 ms after the tone. Plane rotation effects were reduced (but not eliminated) at the short tone-picture stimulus onset asynchrony, but foreshortening effects were not reduced. The results implicate an early, prebottleneck locus for some processes compensating for plane rotation and a subsequent bottleneck or postbottleneck locus for compensation for foreshortening.     

A search asymmetry reversed by figure-ground assignment

We report evidence demonstrating that a search asymmetry favoring concave over convex targets can be reversed by altering the figure-ground assignment of edges in shapes. Visual search for a concave target among convex distractors is faster than search for a convex target among concave distractors (a search asymmetry). By using shapes with ambiguous local figure-ground relations, we demonstrated that search can be efficient (with search slopes around 10 ms/item) or inefficient (with search slopes around 30–40 ms/item) with the same stimuli, depending on whether edges are assigned to concave or convex "figures." This assignment process can operate in a top-down manner, according to the task set. The results suggest that attention is allocated to spatial regions following the computation of figure-ground relations in parallel across the elements present. This computation can also be modulated by top-down processes.     

Attention,spatial representation,and visual neglect: simulating emergent attention and spatial memory in the selective attention for identification model (SAIM)

The selective attention for identification model (SAIM) is presented. This uses a spatial window to select visual information for recognition, binding parts to objects and generating translation-invariant recognition. The model provides a qualitative account of both normal and disordered attention. Simulations of normal attention demonstrate 2-object costs and effects of object familiarity on selection, global precedence, spatial cueing, and inhibition of return. When lesioned, SAIM demonstrated either view- or object-centered neglect or spatial extinction, depending on the type and extent of lesion. The model provides a framework to unify (a) object- and space-based theories of normal selection, (b) dissociations within the syndrome of unilateral neglect, and (c) attentional and representational accounts of neglect.     

Self-esteem in schizophrenia: relationships between self-evaluation,family attitudes,and symptomatology

Participants with schizophrenia (N = 59) were assessed on self-evaluation, symptomatology, and positive and negative affect (expressed emotion) from significant others. An interview-based measure of self-evaluation was used and two independent dimensions of self-esteem were derived: negative and positive evaluation of self. As predicted, negative self-evaluation was strongly associated with positive symptoms, a more critical attitude from family members was associated with greater negative self-evaluation, and analyses supported a model whereby the impact of criticism on patients' positive symptoms was mediated by its association with negative self-evaluation. The interview-based method of self-esteem assessment was found to be superior to the questionnaire because its predictive effects remained after depressed mood was accounted for.     

Inhibition and anticipation in visual search: evidence from effects of color foreknowledge on preview search

We present four experiments in which we examined the effects of color mixing and prior target color knowledge on preview search (Watson & Humphreys, 1997). The task was to detect a target letter (an N or a Z) that appeared along with other new letters, when old distractors remained in the visual field. In some conditions, participants were told the target's color, in others, they were not. Foreknowledge of the target's color produced large improvements in search for both baseline and preview presentations (Experiment 1). For preview presentations, the magnitude of this effect was reduced if the target shared its color with a single colored set of previewed letters (Experiment 2). Removing this similarity across the displays greatly improved search efficiency (Experiment 3). In Experiment 4, we assessed and rejected the proposal that the effects reflected the probability that the target was carried by a particular color. We discuss the results in terms of separate effects of (1) inhibitory carryover from a preview color group and (2) an anticipatory set for a known target color.     

From what to where: neuropsychological evidence for implicit interactions between object- and space- based attention

Three experiments examined nonspatial extinction in G.K., a patient with bilateral parietal damage. Experiment 1 demonstrated nonspatial extinction (poor detection of a weak relative to a stronger perceptual group), even when the stronger group was less complex than the weaker group. Experiment 2 showed improved report of a letter falling at the location of the stronger group, but explicit judgments of the location of the letter were at chance. Experiment 3 replicated the object-cuing benefit, though G.K. could not discriminate whether a letter fell at the same location as the stronger perceptual group. The data indicate coupling between object- and space-based attention, so that spatial attention is drawn to the location occupied by the winner of object-based competition for selection. In this case, what cues where . This coupling operates implicitly, even when explicit location judgments are impaired.     

History matters: the preview benefit in search is not onset capture

Visual search for a conjunction target is made easier when distractor items are temporally segregated over time to produce two separate old and new groups (the new group containing the target item). The benefit of presenting half the distractors first is known as the preview effect. Recently, some researchers have argued that the preview effect occurs because new stimuli capture attention. This account was tested in the present study by using a novel "top-up" condition that exploits the fact that when previews appear only briefly before the search display, there is minimal preview benefit. We show that effects of a brief preview can be "topped up" by an earlier exposure of the same items, even when the preview disappears between its first and second presentations.This top-up effect demonstrates that the history of the old stimuli is important for the preview benefit, contrary to the account favoring onset capture. We discuss alternative accounts of how the preview benefit arises.     

An analysis of the time course of attention in preview search

We used a probe dot procedure to examine the time course of attention in preview search (Watson & Humphreys, 1997). Participants searched for an outline red vertical bar among other new red horizontal bars and old green vertical bars, superimposed on a blue background grid. Following the reaction time response for search, the participants had to decide whether a probe dot had briefly been presented. Previews appeared for 1,000 msec and were immediately followed by search displays. In Experiment 1, we demonstrated a standard preview benefit relative to a conjunction search baseline. In Experiment 2, search was combined with the probe task. Probes were more difficult to detect when they were presented 1,200 msec, relative to 800 msec, after the preview, but at both intervals detection of probes at the locations of old distractors was harder than detection on new distractors or at neutral locations. Experiment 3A demonstrated that there was no difference in the detection of probes at old, neutral, and new locations when probe detection was the primary task and there was also no difference when all of the shapes appeared simultaneously in conjunction search (Experiment 3B). In a final experiment (Experiment 4), we demonstrated that detection on old items was facilitated (relative to neutral locations and probes at the locations of new distractors) when the probes appeared 200 msec after previews, whereas there was worse detection on old items when the probes followed 800 msec after previews. We discuss the results in terms of visual marking and attention capture processes in visual search.