Behavioral Goals Constrain the Selection of Visual Information

Reactive control in suicide ideators and attempters: An examination of the congruency sequence effect in cognitive and emotional Simon tasks

Reactive control is the cognitive ability to adjust thoughts and behaviors when encountering conflict. We investigated how this ability to manage conflict and stress distinguishes suicidal from nonsuicidal individuals. The hypothesis was that suicidal individuals would show poorer reactive control when faced with conflict generated by emotional than neutral stimuli. Hence, individuals with a lifetime history of suicide ideation or attempt and nonsuicidal controls were tested in cognitive and emotional Simon tasks. We examined the congruency sequence effect (CSE) in the Simon tasks as an indication of the efficiency of reactive control in resolving conflict. Whereas controls demonstrated significant CSEs in both tasks, suicide attempters showed a significant CSE in the cognitive task but not in the emotional task. Suicide ideators, on the other hand, displayed marginally significant CSEs in both tasks. Comparing groups with pairwise comparison demonstrated that the difference in CSE was significant only in the emotional task between attempters and controls. Our findings of attempters' inefficiency in adjusting reactive control during the emotional task reflect cognitive inflexibility in coping with conflicting situations during which suicidal individuals become vulnerable to suicide attempts in states of negative emotion.

The contextual goal dependent attentional flexibility (CoGoDAF) framework: A new approach to attention bias in depression

Successful adaptation to the environment requires attentional prioritization of emotional information relevant to the current situational demands. Accordingly, the presence of an attention bias (AB) for both positive and negative information may allow preferential processing of stimuli in line with the current situational goals. However, AB for negative information sometimes becomes maladaptive, being antithetical to the current adaptive needs and goals of an individual, such as in the case of affective disorders such as depression. Although difficulties in flexible shifting between emotional stimuli in depression have increasingly become a topic of discussion in the field, an integrative approach towards biased versus flexible emotional attentional processes remains absent. In the present paper, we advance a novel and integrative view of conceptualizing potentially aberrant affective attention patterns in depression as a function of the current contextual features. We propose that flexible emotional attention takes place as a result of attention prioritization towards goal-relevant emotional stimuli depending upon the current context of the individual. Specifically, the roles of context, distal and proximal goals, and approach and avoidance motivation processes are considered in a unified manner. The empirical, clinical, and interventional implications of this integrative framework provide a roadmap for future psychological and neurobiological experimental and translational research.

How Response Designs and Class Proportions Affect the Accuracy of Validation Data

Reference data collected to validate land-cover maps are generally considered free of errors. In practice, however, they contain errors despite best efforts to minimize them. These errors propagate during accuracy assessment and tweak the validation results. For photo-interpreted reference data, the two most widely studied sources of error are systematic incorrect labeling and vigilance drops. How estimation errors, i.e., errors intrinsic to the response design, affect the accuracy of reference data is far less understood. In this paper, we analyzed the impact of estimation errors for two types of classification systems (binary and multiclass) as well as for two common response designs (point-based and partition-based) with a range of sub-sample sizes. Our quantitative results indicate that labeling errors due to proportion estimations should not be neglected. They further confirm that the accuracy of response designs depends on the class proportions within the sampling units, with complex landscapes being more prone to errors. As a result, response designs where the number of sub-samples is predefined and fixed are inefficient. To guarantee high accuracy standards of validation data with minimum data collection effort, we propose a new method to adapt the number of sub-samples for each sample during the validation process. In practice, sub-samples are incrementally selected and labeled until the estimated class proportions reach the desired level of confidence. As a result, less effort is spent on labeling univocal cases and the spared effort can be allocated to more ambiguous cases. This increases the reliability of reference data and of subsequent accuracy assessment. Across our study site, we demonstrated that such an approach could reduce the labeling effort by 50% to 75%, with greater gains in homogeneous landscapes. We contend that adopting this optimization approach will not only increase the efficiency of reference data collection, but will also help deliver more reliable accuracy estimates to the user community.

Top-Down Processes Override Bottom-Up Interference in the Flanker Task

Distractor interference in the flanker task is commonly viewed as an outcome of unintentional, involuntary processing, a by-product of attention-controlled processing of the target. An important implication of this notion is that the distractors are not subjected to top-down processing of their own. We tested this idea in a modified version of the flanker task, in which letter targets (S or O) were sometimes flanked by ambiguous distractors (a character that could be S or 5 or one that could be O or 0). Distractor interference was dependent on participants' expectations regarding the category of the distractors (i.e., letters or digits). For example, the O-0 distractor interfered with responding to S when it was perceived as a letter, but not when it was perceived as a digit. Hence, participants applied top-down processing to the peripheral distractors independently of the top-down processing applied to the targets. The fact that to-be-ignored peripheral distractors were processed to such a high level raises questions regarding the fundamental differences between target and distractor processing, and the quality of attentional filtering.

Attentional control of the creation and retrieval of stimulus-response bindings

Two experiments studied the degree to which the creation and retrieval of episodic feature bindings is modulated by attentional control. Experiment 1 showed that the impact of bindings between stimulus and response features varies as a function of the current attentional set: only bindings involving stimulus features that match the current set affect behavior. Experiment 2 varied the time point at which new attentional sets were implemented-either before or after the processing of the to-be-integrated stimuli and responses. The time point did not matter, suggesting that the attentional set has no impact on feature integration proper but controls which features get access to and can thus trigger the retrieval of bindings.

Task probability and report of feature information: what you know about what you 'see' depends on what you expect to need

We investigated the influence of dimensional set on report of object feature information using an immediate memory probe task. Participants viewed displays containing up to 36 coloured geometric shapes which were presented for several hundred milliseconds before one item was abruptly occluded by a probe. A cue presented simultaneously with the probe instructed participants to report either about the colour or shape of the probe item. A dimensional set towards the colour or shape of the presented items was induced by manipulating task probability - the relative probability with which the two feature dimensions required report. This was done across two participant groups: One group was given trials where there was a higher report probability of colour, the other a higher report probability of shape. Two experiments showed that features were reported most accurately when they were of high task probability, though in both cases the effect was largely driven by the colour dimension. Importantly the task probability effect did not interact with display set size. This is interpreted as tentative evidence that this manipulation influences feature processing in a global manner and at a stage prior to visual short term memory.

Multiple Goal Management Starts With Attention

Prior studies have shown that attention is allocated to events relevant to the current goal of a person. Until now, research has focused on the implementation of a single goal leaving open the question of how attention is allocated when multiple goals are activated. We examined whether the allocation of spatial attention is affected by the prioritizing of one goal over another. The results of two dot probe studies showed that attention is oriented to stimuli relevant to a goal with high value when simultaneously presented with stimuli relevant to a goal with low value (Experiment 1) and to stimuli relevant to a goal with high expectancy of success that were simultaneously presented with stimuli relevant to a goal with low expectancy of success (Experiment 2). These findings demonstrate that the allocation of spatial attention is dependent on the motivational strength of goal pursuit.

Space, object, and task selection

Within the field of selective attention, two separate literatures have developed, one examining the effect of selection of objects and another examining the effect of selection of features. The present study bridged these two traditions by examining the compatibility effects generated by two features of attended and unattended nontarget (foil) stimuli. On each trial, participants determined either the identity or the orientation of a visual stimulus. Spatial attention was controlled using cues (presented prior to the target frame) designed to involuntarily capture attention. We independently manipulated the stimulus dimension the participants prepared for and the stimulus dimension on which they actually executed the task. Preparation had little influence on the magnitude of compatibility effects from foil stimuli. For attended stimuli, the stimulus dimension used in executing the task produced large compatibility effects, regardless of whether that dimension was prepared. These and other compatibility effects (e.g., Stroop effects) are discussed in relation to an integrative model of attentional selection. The key assumptions are that (1) selection occurs at three distinct levels (space, object, and task), (2) spatial attention leads to semantic processing of all dimensions, and (3) features do not automatically activate responses unless that object is selected for action.

Processing multidimensional objects under different perceptual loads: The priority of bottom-up perceptual saliency

The role of perceptual load in selective attention to multidimensional objects was investigated by independently manipulating the load along the task-relevant and the task-irrelevant dimensions in the central search array, which was flanked by congruent, incongruent, or neutral peripheral distractors. The relative bottom-up perceptual saliency of these dimensions in capturing attention was manipulated between experiments. When the task-relevant dimension was the color of the letter and the task-irrelevant dimension was the visual shape of the letter (Experiment 1), manipulation of the letter shape perceptual load had no impact upon the pattern of congruency effects in responding to the color, i.e., smaller congruency effects under higher color perceptual loads and larger congruency effects under lower color perceptual loads. When the task-relevant dimension was the shape of the letter and the task-irrelevant dimension was the color of the letter (Experiment 2), there were no congruency effects in responding to the letter shape under high color perceptual loads irrespective of the letter shape loads. When only the target and the flanker were colored whereas the distractors in the central array were not (Experiment 3), the task-irrelevant color information reduced or eliminated the impact of letter shape perceptual load on the congruency effects in responding to the letter shape. These findings suggested that selective attention to multidimensional objects follows the general principles suggested by the perceptual load theory, but the bottom-up perceptual saliency plays a primary role in the distribution of attentional resources over objects and dimensions.

Moving from cognition to behavior: What the research says

In 1994, R. G. Lord and P. E. Levy proposed a variant of control theory that incorporated human information processing principles. The current article evaluates the empirical evidence for their propositions and updates the theory by considering contemporary research on information processing. Considerable support drawing from diverse literatures was found for propositions concerning the activation of goal-relevant information, the inhibition of goal-irrelevant information, and the consequences of goal completion. These effects were verified by meta-analytic analyses, which also supported the meaningfulness of such effects on the basis of their unstandardized magnitudes. The authors conclude by proposing new directions for this version of control theory by invoking recent theorizing on goal emergence and the importance of velocity and acceleration information for goal striving and by reviewing research in cognitive neuroscience.

Selective Attention to Specific Features within Objects: Behavioral and Electrophysiological Evidence

Evidence regarding the ability of attention to bias neural processing at the level of single features has been gathering steadily, but most of the experiments to date used arrays with multiple objects and locations, making it difficult to rule out indirect influences from object or spatial attention. To investigate feature-specific selective attention, we have assessed the ability to select and ignore individual features within the same object. We used a negative-priming paradigm in which the color or the direction of internal motion of the object could determine the relevant response. Bidimensional (colored and moving) and unidimensional (colored and stationary, or gray and moving) stimuli appeared in unpredictable order. In successive blocks, participants were instructed that one feature dimension was dominant. During that block, participants responded according to the dominant dimension for bidimensional stimuli. For unidimensional stimuli, participants responded to the only dimension of the stimulus that afforded a response, regardless of the instruction for the block. The ability to inhibit irrelevant task information at the level of specific features (negative priming for features) was indexed by a decrease in performance to detect one particular feature value (e.g., red) if the same feature value (red) but not another color value (green) had been ignored in the previous bidimensional stimulus. Behavioral results confirmed the existence of inhibitory, negative-priming mechanisms at the singlefeature level for both color and motion dimensions of stimuli. Event-related potentials recorded during task performance revealed the dynamics of neural modulation by feature attention. Comparisons were made using the identical physical stimuli under different conditions of attention to isolate purely attentional effects. Processing of identical bidimensional stimuli was compared as a function of the dimension of attention (color, motion). Processing of identical unidimensional stimuli that followed bidimensional stimuli was also compared to identify possible effects of feature-specific negative priming. The electrophysiological effects revealed that inhibition of irrelevant features leads to modulation of brain activity during early stages of perceptual analysis.

Location specificity in response selection processes for visual stimuli

We used the psychological refractory period paradigm, in which participants respond to two successive tasks (T1 and T2). We created in T2 spatial and color Simon effects, known to be caused by response selection processes. Previous studies in which the spatial Simon effect was manipulated in T2 showed that this effect was underadditive, with stimulus onset asynchrony (SOA) between the targets for T1 and T2. In Experiment 1, we replicated these results with two versions of the spatial Simon effect. In contrast, in Experiment 2 we manipulated two versions of a color Simon effect, revealing an additive relation between the color Simon effect and SOA. These results suggest that the underadditivity obtained with the spatial Simon effect is due to its spatial nature, and that space may play a unique role in response selection processes.

Selective attention and the perception of an attended nontarget object

Although many theories of attention assume that attending to an object results in the processing of all its feature dimensions, there has been no direct evidence that the irrelevant dimensions of an attended nontarget object are encoded. This article explores factors that modulate such processing. In 6 experiments, participants made a speeded response to a probe preceded by a prime that varied in 2 dimensions. Their reaction times to the probe were influenced by the response compatibility between the relevant and irrelevant dimensions of the prime. Furthermore, the effect was observed only when attention was directed to a nonlocation object feature and when participants' reaction times were relatively long. These results suggest that the effect of attention on a nontarget object is more complex than was previously understood.

Goal-driven selective attention in patients with right hemisphere lesions: how intact is the ipsilesional field?

Patients with right hemisphere (RH) lesions often display a spatial bias in attention towards the ipsilesional hemifield. The behavioural manifestations of this spatial bias are typically interpreted as reflecting increased or enhanced attention for stimuli within the 'intact' ipsilesional field, and impaired attentional functioning within the contralesional field. In the healthy brain, goal-driven and stimulus-driven attentional processes interact to determine which stimuli should be prioritized for selection. Although unilateral brain damage increases the relative attentional salience of stimuli within the ipsilesional field, it might also cause problems in filtering or attenuating task-irrelevant information. We examined whether goal-driven attention modulates the processing of ipsilesional and contralesional information in 6 patients with unilateral brain damage following RH stroke (5 male, 1 female; mean age 60.8 years) and a group of age and sex-matched controls. We used a flanker task in which participants made speeded judgements on a central target item (a coloured letter). On each trial the target was flanked by a coloured letter in the left and right hemifields. In separate blocks, participants were instructed to judge either the identity or the colour of the central target and to ignore the flankers. The flanker on one side could be congruent, incongruent or neutral with respect to the target, on either the letter or the colour dimension, whereas the flanker on the other side was always neutral on both dimensions. Healthy controls showed significant interference from incongruent flankers on either side. Crucially, however, this effect only occurred for the task-relevant dimension [F(2,10) = 24.60; P < 0.001]. For patients, however, both the task-relevant and task-irrelevant dimensions of ipsilesional flankers interfered with response times [task-relevant: F(2,10) = 7.50, P < 0.05; task-irrelevant: F(1,5) = 6.20, P < 0.05]. Conversely, contralesional flankers influenced response times only when the target and distractor were incongruent on the task-relevant dimension [F(2,10) = 4.85; P < 0.05]. Our findings demonstrate that following RH damage, goal-driven biases cannot constrain the processing of task-irrelevant features of ipsilesional stimuli. We speculate that a lateralized bias in spatial attention leads to unselective prioritization of all feature-based attributes of stimuli appearing within the ipsilesional hemifield, whether or not they are relevant to performance. Attentional selection for ipsilesional stimuli in disorders such as spatial neglect and extinction may not therefore be entirely normal, as previously assumed.

The overlay interference task and object-selective visual attention

A series of experiments was carried out to examine object-based visual attention in an interference task. Observers were presented with two transparently overlapping equilateral triangles forming a "Star of David". One of these triangles was darker than the background, the other was lighter than the background. The observers were required to make a speeded choice response to the orientation of the darker triangle. The presence of the light triangle produced a robust interference effect that manifested as a slower response time. This effect was strongly modulated by the relative contrast of the target and distractor triangles. It was reduced when the light distractor triangle was separated in depth from the target triangle. Since the configuration rules out the possibility of 2-D spatial selection, it is concluded that object-based selection occurs in interference tasks and that the effectiveness of this selection is modulated by visual attributes that are not directly relevant to the task.

A dissociation between attention and selection

It is widely assumed that the allocatian of spatial attention results in the "selection" of attended objects or regions of space. That is, once a stimulus is attended, all its feature dimensions are processed irrespective of their relevance to behavioral goals. This assumption is based in part on experiments showing significant interference for attended stimuli when the response to an irrelevant dimension conflicts with the response to the relevant dimension (e.g., the Stroop effect). Here we show that such interference is not due to attending per se. In two spatial cuing experiments, we found that it was possible to restrict processing of attended stimuli to task-relevant dimensions. This new evidence supports two novel conclusions: (a) Selection involves more than the focusing of attention per se: and (b) task expectations play a key role in detertnining the depth of processing of the elementary feature dimensions of attended stimuli.

Effects of attention and emotion on face processing in the human brain: an event-related fMRI study

We used event-related fMRI to assess whether brain responses to fearful versus neutral faces are modulated by spatial attention. Subjects performed a demanding matching task for pairs of stimuli at prespecified locations, in the presence of task-irrelevant stimuli at other locations. Faces or houses unpredictably appeared at the relevant or irrelevant locations, while the faces had either fearful or neutral expressions. Activation of fusiform gyri by faces was strongly affected by attentional condition, but the left amygdala response to fearful faces was not. Right fusiform activity was greater for fearful than neutral faces, independently of the attention effect on this region. These results reveal differential influences on face processing from attention and emotion, with the amygdala response to threat-related expressions unaffected by a manipulation of attention that strongly modulates the fusiform response to faces.