Temporal dynamics of spatial attentional biases toward weight-related words among females with weight dissatisfaction

Attentional bias toward weight-related stimuli plays a crucial role in the development and maintenance of body image disturbances. However, the temporal dynamics of attentional biases responsible for the previously reported behavioral effects caused by the task-irrelevant but spatial-relevant weight-related stimuli presented in the peripheral visual field among females with high weight dissatisfaction (HWD) remain unclear. The present study combined the modified dot-probe task and event-related potentials to explore the temporal dynamics of spatial attentional biases toward weight-related words among females with HWD. The results showed significantly larger N2pc amplitudes were elicited by fat-related and thin-related words than neutral words only in the HWD group. Moreover, only fat-related words elicited a significant PD for the HWD group, and the PD amplitudes were larger in the HWD group than in the control group. These findings revealed that weight-related words initially captured spatial allocation among females with HWD, and then fat-related words were actively suppressed after the initial capturing.

Suppression of salient stimuli inside the focus of attention

We investigated how attention is distributed when one of two attended stimuli stands out from the visual context. Participants judged whether the line orientations within two geometric shapes at two predictable locations were same or different, which induced a wide focus of attention around the two locations. One of the geometric shapes surrounding the lines could be a salient color or shape singleton but was irrelevant for the task. In Experiment 1, the salient and non-salient items were both placed on the horizontal midline. Electrophysiological recordings at posterior electrode locations PO7/8 revealed a positivity between 200 and 300 ms contralateral to the singleton, consistent with the occurrence of the P_D. The P_D is thought to reflect attentional suppression. In Experiment 2, one attended item was placed on the vertical meridian and the other one on a lateral position. Lateral line targets triggered robust N2pc components when there was no singleton present, reflecting attentional selection. However, this N2pc to lateralized line targets was abolished when a singleton was presented at the same lateral position, and conversely, was increased when a singleton was presented on the vertical position. This suggests that salient elements inside the focus of attention are suppressed and attention is enhanced at the other location. It can be concluded that salient elements inside the focus of attention do not capture attention, as bottom-up control of attention would propose, but that salient elements are suppressed, possibly to assure unbiased processing of equally relevant stimuli.

Active suppression of salient-but-irrelevant stimuli does not underlie resistance to visual interference

In visual search for a shape target, interference from salient-but-irrelevant color singletons can be resisted in feature search mode, but not in singleton detection mode. In singleton detection mode, we observed a contralateral positivity (P_D) after 260-340ms, suggesting that the salient distractor was suppressed. Because RTs in singleton detection mode increased when a distractor was present, we conclude that active suppression of distractors takes time. In feature search mode, no increase in RTs and no P_D to the distractor was observed, showing that resistance to interference was not accomplished by suppression. Rather, the smaller N2pc to the target in feature search than in singleton detection mode suggests that enhancement of target features avoided interference. Thus, the strong top-down set in feature search mode eliminated the need to suppress the early attend-to-me signal (corresponding to the Ppc, from 160 to 210ms) that was generated by salient stimuli independently of search mode.

Attentional Selection and Suppression in Children With Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder with prominent impairments in directing and sustaining attention. The aim of this study was to identify the neurophysiologic bases of attention deficits in ADHD, focusing on electroencephalography markers of attentional selection (posterior contralateral N2 [N2pc]) and suppression (distractor positivity [P_D]).

METHODS

The electroencephalography data were collected from 135 children 9-15 years old with and without ADHD while they searched for a shape target in either the absence (experiment 1) or the presence (experiment 2) of a salient but irrelevant color distractor.

RESULTS

In experiment 1, the shape target elicited a smaller N2pc in children with ADHD (n = 38) compared with typically developing children (n = 36). The smaller N2pc amplitude predicted higher levels of inattentive symptoms in children with ADHD. Moreover, the target-elicited N2pc was followed by a positivity in typically developing children but not in children with ADHD. In experiment 2, the salient but irrelevant color distractor elicited a smaller P_D component in children with ADHD (n = 32) compared with typically developing children (n = 29). The smaller P_D predicted higher inattentive symptom severity as well as lower behavioral accuracy in children with ADHD.

CONCLUSIONS

The correlation between N2pc/P_D amplitudes and ADHD symptom severity suggests that these signals of attentional selection and suppression may serve as potential candidates for neurophysiologic markers of ADHD. Our findings provide a neurophysiologic basis for the subjective reports of attention deficits in children with ADHD and highlight the importance of spatial attention impairments in ADHD.