Tasting inhibition: A proof-of-concept study of the food stop-signal game.

Self-Control is an important skill in everyday life when attention is automatically drawn toward certain stimuli. For instance, food stimuli automatically capture visual attention and are processed preferentially. Therefore, efficient response inhibition is crucial to refrain from careless overeating. In the present proof-of-concept study we use a novel adaptation of a previously evaluated Stop-Signal Game (SSG) to measure reactive, food-specific, response inhibition in healthy adults. We analyzed a sample of 83 participants (60 female, mean age=24.1, mean BMI=21.71kg/m2) split into three groups. In a gamified stop-signal task, participants navigated an avatar in an urban environment toward high-calorie food, low-calorie food, or non-food stimuli in go-trials and were asked to inhibit the approach reaction in stop-trials. Hunger, eating styles, food craving, and impulsivity were assessed via self-reports to investigate their relationship with (food-specific) response inhibition. Results showed that response inhibition (in terms of stop-signal reaction time, SSRT) did not differ between the high-calorie, low-calorie, and non-food SSG which might be explained by characteristics of the sample. However, impulsivity was positively correlated with SSRT in the low-calorie SSG, whereas food-craving and hunger were positively related to response inhibition in the high-calorie SSG. Future studies could build upon the food SSG to measure and train food-specific response inhibition in the treatment of overeating.

The influence of selective attention to specific emotions on the processing of faces as revealed by event-related brain potentials.

Event-related potential studies using affective words have indicated that selective attention to valence can increase affective discrimination at early perceptual stages. This effect most likely relies on neural associations between perceptual features of a stimulus and its affective value. Similar to words, emotional expressions in human faces are linked to specific visual elements. Therefore, selectively attending to a given emotion should allow for the preactivation of neural networks coding for the emotion and associated first-order visual elements, leading to enhanced early processing of faces expressing the attended emotion. To investigate this, we employed an expression detection task (N = 65). Fearful, happy, and neutral faces were randomly presented in three blocks while participants were instructed to respond only to one predefined target level of expression in each block. Reaction times were the fastest for happy target faces, which was accompanied by an increased occipital P1 for happy compared with fearful faces. The N170 yielded an arousal effect (emotional > neutral) while both components were not modulated by target status. In contrast, the early posterior negativity (EPN) arousal effect tended to be larger for target compared with nontarget faces. The late positive potential (LPP) revealed large effects of status and expression as well as an interaction driven by an increased LPP specifically for nontarget fearful faces. These findings tentatively indicate that selective attention to facial affect may enhance early emotional processing (EPN) even though further research is needed. Moreover, late controlled processing of facial emotions appears to involve a negativity bias.

Event-related potentials of food-induced blindness in the rapid serial visual presentation paradigm.

Emotion-induced blindness is known as the impairment in the identification of targets that follow shortly after emotional distractors in the rapid serial visual presentation (RSVP) paradigm. Besides negative or erotic stimuli, food distractors have also been found to elicit a similar effect. This indicates an attentional bias for food stimuli in the temporal dimension of visual attention, which is highly relevant in the context of eating behaviour. So far, the neural mechanisms of this food-induced blindness are widely unknown. In the present study (N = 53), we investigated event-related potentials (ERPs) in response to food distractors and non-food targets in a single-target RSVP task. Automatic capture of visual attention by task-irrelevant food distractors was evident in enhanced Distractor Negativity (N2) and Early Food Positivity (P1). However, food distractors did not elicit a P3b. Thus, apparently, not the encoding of food distractors in working memory but alternative attentional processes are responsible for the food-induced blindness. Reduced target P3b reflected errors in target identification but was unaffected by the preceding distractor. In contrast, target N2 was specifically reduced for unidentified targets preceded by food distractors. Presumably, the attentional capture of food distractors may have caused a reduction of target N2, thereby contributing to the impairment in target identification. However, future research is needed to confirm this assumption and bridge the gap between the food-induced blindness on the behavioural level and the attentional capture of food stimuli reflected in the distractor ERPs.

Attentional tuning of valent word forms.

Using event-related brain potentials (ERPs), we tested the hypothesis of valent word forms (Kissler et al., 2006, Prog Brain Res) stating that the mere visual shapes of emotional words acquire valence through numerous co-occurrences with affective activation over an experienced reader's life. Thereby, associations between neuronal representations of visual word forms and affect are strengthened. If so, selective attention to a specific level of the valence of single visual words should not only pre-activate neuronal representations of that level of valence, but this activation should also spread to the associated word forms. This should improve their processing and/or affective discrimination. In a valence-detection task, N = 53 participants made speeded responses only to words of the current target level of valence (negative, neutral, or positive), which varied across separate blocks. We focused on posterior visual P1 and N170 components, two well-established ERP markers of low-level and structural word form processing, respectively. P1 increased from negative over neutral to positive words; this effect was stronger in target compared to nontarget words. N170 was larger for emotional compared to neutral target words, whereas nontarget words showed a strong reverse pattern. The P1 effect for target words and the N170 effect for nontarget words both were driven by good task performers in terms of fast hit responses. Results support the idea of valent word forms that can be tuned by selective attention to valence, which implies both, facilitated affective discrimination and processing of target words, and inhibition of the processing of nontarget words.

Attention to affect 2.0: Multiple effects of emotion and attention on event-related potentials of visual word processing in a valence-detection task.

Here we continue recent work on the specific mental processes engaged in a valence-detection task. Fifty-seven participants responded to one predefined target level of valence (negative, neutral, or positive), and ignored the remaining two levels. This enables more precise fine-tuning of neuronal pathways, compared to valence categorization where attention is divided between different levels of valence. Our group recently used valence detection with emotional words. Posterior P1 and N170 effects in the event-related potential (ERP) supported the idea of valent word forms that can be tuned by selective attention to valence. Here we report findings on three distinct posterior N2 components, P300, N400, and the late positive potential (LPP). Target but not nontarget words showed an arousal effect (emotional > neutral) on left-side early posterior negativity (180-280 ms). In contrast, an arousal effect on a sharp N2 deflection in left-minus-right difference ERPs (230-270 ms), suggesting facilitation of lexical access for emotional words, was independent of target status. This also applied to increased medial parieto-occipital N2 (260-300 ms) specific to negative words, indicating attentional capture. Medial-central N400 was specifically enhanced for negative nontarget words, further supporting attentional capture. The typical LPP arousal effect was observed, being stronger and more left-lateralized in target words. An exploratory finding concerned a broad component-overarching ERP valence effect (250-650 ms). Independent of target status, ERPs were more positive for positive than negative words. Combined with our previous results, data suggest multiple loci of emotion-attention interactions in valence detection.

Effects of the calorie content of visual food stimuli and simulated situations on event-related frontal alpha asymmetry and event-related potentials in the context of food choices.

Approach and avoidance tendencies play an important role in everyday food choices when choosing between high-caloric, rather unhealthy, and low-caloric, rather healthy options. On a neuronal level, approach and avoidance motivation have been associated with asymmetrical activity of the frontal cortex, often quantified by alpha power averaged over several seconds of resting electroencephalogram (EEG). Going beyond the analysis of resting EEG, the present study aimed to investigate asymmetrical frontal activity in direct response to food stimuli in an event-related design and in combination with event-related potentials (ERPs). Therefore, a sample of 56 young and healthy participants completed a food choice task. They were asked to choose from a selection of high-caloric and low-caloric foods which they would want to eat on a normal day (baseline), when being on a diet, and in a reward situation. On the behavioural level, there was a clear preference for low-caloric foods. Well in line with that, time-frequency analyses of alpha asymmetry revealed relatively stronger temporary (950-1175 ms) left-hemispheric frontal activity, that is, a stronger approach tendency, in response to low-caloric as compared to high-caloric foods. Furthermore, larger P300 for low-caloric foods indicated an increased task relevance of low-caloric foods in the baseline and the reward situation. In contrast, the late positive potential (LPP), an index of subjective value, was larger for high-as compared to low-caloric foods, reflecting the intrinsic rewarding properties of high-caloric foods. ERPs, but not frontal alpha asymmetry, were influenced by the situational context.

Helpless against food cues: the influence of pro- and anti-sugar videos on instrumental food-seeking behaviour in a Pavlovian-to-instrumental transfer paradigm.

OBJECTIVE: External food cues can trigger food seeking by means of associative Stimulus-Outcome-Response learning mechanisms. These mechanisms can contribute to cued overeating. The present study aims at investigating if (cued) food-seeking behaviour can be influenced by pro- and anti-sugar videos. DESIGN: Participants (N = 81) completed a Pavlovian-to-instrumental transfer (PIT) task: in an instrumental training, they learned associations between button presses and resulting sugary or sugar-free snacks. In a subsequent Pavlovian training, the snacks were paired with different cues. During the following transfer test, participants performed free button presses to win snacks while the cues were present or not. MAIN OUTCOME MEASURES: The number of button presses for the different snacks in the transfer test was analysed. RESULTS: We observed an outcome specific PIT effect, i.e. higher response rates for cued snacks. The videos did not affect the PIT effect. However, exploratory analyses revealed that the anti-sugar video led to fewer button presses for sugary snacks (compared to the pro-sugar video). CONCLUSION: While snack-seeking behaviour was unaffected by the video's messages in the presence of food cues, in the absence of food cues there was evidence for a reduction of sugary snack choices by the anti-sugar video.

Attention please: ERP evidence for prime-target resource competition in the neutral-target variant of affective priming.

Using event-related potentials we examined the mechanisms that underlie the influence of affective context information on evaluative judgments in affective priming (AP). Participants (N = 44) evaluated a priori neutral target ideographs that were preceded by 800-ms negative, neutral or positive prime pictures. We observed a significant AP effect (APE), with more positive target ratings for targets following positive versus negative primes, with neutral primes lying in between. A greater individual APE was associated with increased attention for the primes, indicated by larger amplitudes of parietal positive slow wave (PSW) and more pronounced prime affect discrimination mirrored in affect-specific variations of parieto-occipital prime P1 and parietal prime P2, P300, and PSW amplitudes. This confirms previous theoretical and empirical work suggesting that the size of the APE critically depends on the extent of prime-elicited affective activation. Furthermore, a greater individual APE was related to generally reduced depth of target processing as mirrored in smaller overall amplitudes of attention-sensitive target-related P1, P2, P300, and PSW. In addition, in the total sample P2, P300, and PSW were smaller for targets following AP eliciting, attention-capturing emotional, as compared to neutral primes. Based on the observed coincidence of increased processing of affective versus neutral primes, and specifically reduced processing of those targets that followed affective primes, we propose prime-target resource competition as an additional, not yet described process contributing to AP in the neutral-target paradigm.

Food has the right of way: Evidence for prioritised processing of visual food stimuli irrespective of eating style.

Visual attention for food is likely to play an important role for overeating. The attentional bias for visual food stimuli was investigated with respect to self-reported restrained, external and emotional eating style. Using a Rapid Serial Visual Presentation task (N = 103), the effects of visual food stimuli in the context of the attentional blink were examined. Food targets enhanced the attentional blink when presented as first targets in a rapid stream of pictures and impaired the identification of preceding non-food targets in terms of a backward interference when presented as second targets. Task irrelevant food distractors interfered with the identification of subsequent non-food targets. The effects provide evidence for a prioritisation of food stimuli in the allocation of attentional resources. The attentional bias for food emerged as a universal phenomenon irrespective of personal eating style. Therefore, enhanced attention for visual food stimuli seems to play no direct causal role in eating styles associated with overeating.