Trial-to-trial carryover effects on spatial attentional bias

Visual Probe Tasks (VPTs) have been extensively used to measure spatial attentional biases, but as usually analysed, VPTs do not consider trial-to-trial carryover effects of probe location: Does responding to a probe on, e.g., the location of a threat cue affect the bias on the subsequent trial? The aim of the current study was to confirm whether this kind of carryover exists, using a novel task version, the diagonalized VPT, designed to focus on such trial-to-trial interactions. Two versions of the task were performed by a sample of college students. In one version cues were coloured squares; in the other, cues were threat-related and neutral images. Both versions included partially random positive or negative response feedback and varying Cue-Probe Intervals (200 or 600 ms). Carryover effects were found in both versions. Responding to a probe at the location of a cue of a given colour induced an attentional bias on the subsequent trial in the direction of that colour. Responding to a threat-related cue induced an attentional bias towards threat on the subsequent trial. The results provide evidence that trial-to-trial carryover effects on spatial attentional bias indeed exist. A methodological implication is that previous probe location could be considered in analyses or re-analyses of spatial visual attention tasks.

Association between depressive symptom clusters and food attentional bias

BACKGROUND

The mechanisms underlying the depression-obesity relationship are unclear. Food attentional bias (FAB) represents one candidate mechanism that has not been examined. We evaluated the hypothesis that greater depressive symptoms are associated with increased FAB.

METHOD

Participants were 89 normal weight or overweight adults (mean age = 21.2 ± 4.0 years, 53% female, 33% non-white, mean body mass index in kg/m2 = 21.9 ± 1.8 for normal weight; 27.2 ± 1.5 for overweight). Total, somatic, and cognitive-affective depressive symptom scores were computed from the Patient Health Questionnaire-8 (PHQ-8). FAB scores were calculated using reaction times (RT) and eye-tracking (ET) direction and duration measures for a food visual probe task. Age, gender, race/ethnicity, and body fat percent were covariates.

RESULTS

Only PHQ-8 somatic symptoms were positively associated with RT-measured FAB (β = 0.23, p = .04). The relationship between somatic symptoms and ET direction (β = 0.18, p = .17) and duration (β = 0.23, p = .08) FAB indices were of similar magnitude but were not significant. Somatic symptoms accounted for 5% of the variance in RT-measured FAB. PHQ-8 total and cognitive-affective symptoms were unrelated to all FAB indices (ps ≥ 0.09).

CONCLUSIONS

Only greater somatic symptoms of depression were linked to food attentional bias as measured using reaction time. Well-powered prospective studies should examine whether this bias replicates, particularly for eye-tracking measures, and whether it partially mediates the depression-to-obesity relationship.

Internal reliability of the alcohol-related visual probe task is increased by utilising personalised stimuli and eye-tracking

BACKGROUND

In the current study, we investigated whether the internal reliability of the visual probe task measure of attentional bias for substance-related cues could be improved by incorporating eye-tracking methods and personalised stimuli.

METHOD

Sixty social drinkers completed two visual probe tasks: one with a broad range of different alcohol pictures, the other containing only images of the participants' preferred drink. Attentional bias was inferred from manual reaction times to probes replacing the pictures, and from the duration of eye movement fixations towards the pictures (gaze dwell time).

RESULTS

Internal reliability was highest for personalised (versus general) alcohol stimuli, and for eye-tracking (versus manual reaction time) measures of attentional bias. The internal reliability of both reaction time (α=.73) and gaze dwell time measures (α=.76) of attentional bias for personalised alcohol stimuli was acceptable. Internal reliability of indices of attentional bias for general alcohol stimuli was inferior, although better for the gaze dwell time (α=.51) compared to the reaction time measure (α=.19). Attentional bias towards personalised stimuli was larger than bias to general stimuli, but only for the reaction time measure. There were no statistically significant associations between measures of attentional bias and alcohol consumption or craving.

CONCLUSIONS

Adopting personalised stimuli and eye movement monitoring significantly improves the internal reliability of the alcohol-related visual probe task.

Test-retest reliability of eye tracking during the visual probe task in cocaine-using adults

BACKGROUND

Stimuli associated with cocaine use capture attention. Evidence suggests that fixation time measured on the visual probe task is a valid measure of cocaine cue attentional bias. The aim of this experiment was to demonstrate the test-retest reliability of cocaine cue attentional bias as measured by fixation time during the visual probe task.

METHODS

In a within-subject, repeated-measures design, thirty-six non-treatment seeking cocaine-using adults completed a visual probe task with eye tracking.

RESULTS

Participants displayed an attentional bias to cocaine-related images as measured by fixation time across two occasions (F (1, 35) = 56.5, p < 0.0001). A Pearson correlation indicated significant test-retest reliability for this effect (r = 0.51, p = 0.001). Response time failed to detect an attentional bias and test-retest reliability was low (r = 0.24, p = 0.16).

CONCLUSION

Fixation time during the visual probe task is a reliable measure of cocaine cue attentional bias in cocaine-using adults across time.

Attentional bias to food-related visual cues: is there a role in obesity?

The incentive sensitisation model of obesity suggests that modification of the dopaminergic associated reward systems in the brain may result in increased awareness of food-related visual cues present in the current food environment. Having a heightened awareness of these visual food cues may impact on food choices and eating behaviours with those being most aware of or demonstrating greater attention to food-related stimuli potentially being at greater risk of overeating and subsequent weight gain. To date, research related to attentional responses to visual food cues has been both limited and conflicting. Such inconsistent findings may in part be explained by the use of different methodological approaches to measure attentional bias and the impact of other factors such as hunger levels, energy density of visual food cues and individual eating style traits that may influence visual attention to food-related cues outside of weight status alone. This review examines the various methodologies employed to measure attentional bias with a particular focus on the role that attentional processing of food-related visual cues may have in obesity. Based on the findings of this review, it appears that it may be too early to clarify the role visual attention to food-related cues may have in obesity. Results however highlight the importance of considering the most appropriate methodology to use when measuring attentional bias and the characteristics of the study populations targeted while interpreting results to date and in designing future studies.

A highly selective ratiometric visual and red-emitting fluorescent dual-channel probe for imaging fluoride anions in living cells

Recently, growing attention has been paid to the accurate determination of fluoride anion (F(-)) in the environment and living systems for its toxicity and biological function investigation. In this paper, we developed a ratiometric visual and red-emitting fluorescent dual-channel probe (1) employed Si-O bond as a highly selective recognition receptor for imaging F(-) in living cells. Probe 1 possesses a potential internal charge transfer (ICT) structure, and displays a large (158 nm) red-shifted absorption spectrum and the color changes from yellow to blue upon addition of F(-) in the aqueous solution. In addition, probe 1 can be used to detect F(-) quantitatively by the ratiometric absorption and turn-on fluorescence spectroscopy methods with excellent sensitivity. Finally, the results of its application to bioimaging of F(-) in living cells show that probe 1 would be of great benefit to biomedical researchers for investigating the effects of fluoride in biological systems.