Interference effect of food and emotional stimuli in Stroop-like tasks for children and adults with Prader-Willi Syndrome

Interference effect of food and emotional stimuli in Stroop-like tasks for children and adults with Prader-Willi Syndrome. The aim of this work was to study the way items related to food or emotion are processed by a population known to have difficulties with dietary restriction, namely individuals with Prader-Willi Syndrome (PWS). Given the presence of intellectual disability (ID) in PWS, our experiments were designed to examine whether these difficulties were specific to PWS or linked with their ID. Two modified Stroop tasks (i.e., a food version and an emotional version) were administered to seventy-four children (aged between 6 and 16 years old) divided into three groups (one with PWS, one with ID matched on age and Intellectual Quotient (IQ), and one healthy group matched on age) and to eighty-four adults (aged between 18 and 48 years old) distributed in the same three groups. For both tasks, a picture version was used for the children and a word version for the adults. For the food Stroop task, (Experiment 1), materials were composed of low or high-caloric food items and stimuli not related to food. The results show a food Stroop effect for children and adults with PWS that was absent in the group of healthy participants. Moreover, a food Stroop effect was also significant for adults with ID. For the emotional Stroop task (Experiment 2), materials were composed of negative, positive and neutral stimuli. The emotional Stroop effect was also obtained for children and adults with PWS as well as for the healthy group, but not for the age- and IQ-matched group. For the PWS groups, results show a preservation to process positive pictures for children and difficulties to process negative stimuli for both age-groups. These results suggest that people with PWS have difficulties in disengaging their attention when food stimuli are present in their environment and poorer abilities to process negative ones. These difficulties endure in adulthood.

The Influence of Negative Orthographic Neighborhood in the Lexical Decision Task: Valence and Arousal Contributions

This study investigated whether the visual recognition of neutral words might be influenced by the emotional dimensions (i.e., valence and arousal) of orthographically similar lexical representations, and whether this might also depend on emotional-related traits of participants (i.e., alexithymia). To this end, 108 participants performed a lexical decision task with 80 neutral words with a higher frequency orthographic neighbor that varied in valence (from neutral to negative) and arousal (from low to high). The main finding was the expected interaction effect between the valence and arousal of the neighbor on the lexical decision times of neutral stimulus words. Longer reaction times were found when the valence score of the neighbor decreased from neutral to negative for words with a low-arousal orthographic neighbor while this emotional neighbor effect was reversed for words with a high-arousal negative neighbor. This combined influence of the valence and arousal of the neighbor was interpreted in terms of increased lexical competition processes and direct influence of the affective system on the participant's response. Moreover, this interaction effect was smaller when the level of alexithymia of the participants increased, suggesting that people with a higher level of alexithymia are less sensitive to the emotional content of the neighbor. The results are discussed within an interactive activation model of visual word recognition incorporating an affective system with valence and arousal dimensions, with regard to the role of the alexithymia level of participants.

Animacy and attentional processes: Evidence from the Stroop task

In visual perception, evidence has shown that attention is captured earlier and held longer by animate than inanimate stimuli. The former are also remembered better than the latter. Thus, as far as attentional processes are concerned, animate entities have a privileged status over inanimate entities. We tested this hypothesis further using an adaptation of the Stroop paradigm. Adults had to categorise the colours of words that referred to either animate or inanimate concepts. In two experiments, we found that it took longer to process the ink colour of animate than inanimate words. Indeed, this effect was found when the words were presented in an oral animacy Stroop task (Experiment 1) and in a manual animacy Stroop task (Experiment 2). Using ex-Gaussian analyses and examining the distribution of RTs as a function of vincentiles per animacy condition, we did not find a specific localisation of the animacy effect. The findings are interpreted as providing further evidence that animates are prioritised in processing because their fitness value is higher than that of inanimates.

The effect of orthographic and emotional neighbourhood in a colour categorization task

This study investigated whether and how the strength of reading interference in a colour categorization task can be influenced by lexical competition and the emotional characteristics of words not directly presented. Previous findings showed inhibitory effects of high-frequency orthographic and emotional neighbourhood in the lexical decision task. Here, we examined the effect of orthographic neighbour frequency according to the emotional valence of the higher-frequency neighbour in an emotional orthographic Stroop paradigm. Stimuli were coloured neutral words that had either (1) no orthographic neighbour (e.g. PISTIL [pistil]), (2) one neutral higher-frequency neighbour (e.g. tirade [tirade]/TIRAGE [draw]) or (3) one negative higher-frequency neighbour (e.g. idiome [idiom]/IDIOTE [idiotic]). The results showed that colour categorization times were longer for words with no orthographic neighbour than for words with one neutral neighbour of higher frequency and even longer when the higher-frequency neighbour was neutral rather than negative. Thus, it appears not only that the orthographic neighbourhood of the coloured stimulus words intervenes in a colour categorization task, but also that the emotional content of the neighbour contributes to response times. These findings are discussed in terms of lexical competition between the stimulus word and non-presented orthographic neighbours, which in turn would modify the strength of reading interference on colour categorization times.