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LA CODIFICA RELATIVA E ASSOLUTA DI STIMOLI VISIVI E TATTILI NELL’EFFETTO SIMON
No full textL’effetto Simon dimostra che la dimensione spaziale di uno stimolo è automaticamente elaborata dal nostro sistema cognitivo anche quando questa è irrilevante per il compito. Diverse evidenze sperimentali hanno dimostrato che la codifica spaziale di uno stimolo visivo può avvenire in base a più cornici di riferimento quando lo stimolo viene presentato in una di quattro possibili posizioni orizzontali sullo schermo. L’effetto Simon si osserva sia rispetto alla posizione assoluta dello stimolo (posizione destra/ sinistra rispetto al centro dello
schermo) che relativa (posizione destra/sinistra rispetto all’emispazio sinistro o destro dello schermo). L’obiettivo di questo studio è quello di definire se le cornici di riferimento osservate per il Simon con stimoli visivi siano analoghe a quelle osservate con stimoli tattili. In un primo studio, i partecipanti dovevano rispondere alla frequenza di uno stimolo visivo (accensione di una luce) o tattile (stimolazione delle dita) utilizzando due pedali posizionati a sinistra o a destra, mentre veniva manipolata la posizione dello stimolo assoluta e relativa (con stimoli visivi e tattili presentati vicino/sulle mani). Mentre per gli stimoli tattili è emerso un effetto Simon assoluto e che questo veniva modulato dal Simon relativo, per quelli visivi non è emerso alcun effetto Simon significativo. Per capire se la caratteristica rilevante dello stimolo visivo (frequenza) possa spiegare la mancata presenza dell’effetto Simon visivo, è stato condotto un nuovo esperimento in cui i partecipanti dovevano rispondere alla forma dello stimolo (quadrato-rombo), mentre la posizione degli stimoli e delle risposte è rimasta invariata. I risultati confermano quanto emerso nel primo studio
On the spread of spatial attention in touch: Evidence from event-related brain potentials
Full text linkTo investigate the distribution of tactile spatial attention near the current attentional
focus, participants were cued to attend to one of four body locations (hand or shoulder on the left or right side) to respond to infrequent tactile targets. In this narrow attention task, effects of spatial attention on the ERPs elicited by tactile stimuli delivered to the hands were compared as a function of the distance from the attentional focus (Focus on the hand vs. Focus on the shoulder). When participants focused on the hand, attentional modulations of the sensory-specific P100 and N140 components were followed by the longer latency Nd component. Notably, when participants focused on the shoulder, they were unable to restrict their attentional resources to the cued location, as revealed by the presence of reliable attentional modulations at the hands. This effect of attention outside the attentional focus was delayed and reduced compared to that observed within the attentional focus, revealing the presence of an attentional gradient. In addition, to investigate whether the size of the attentional focus modulated the effects of tactile spatial attention on somatosensory processing, participants also completed the Broad attention task, in which they were cued to attend to two locations (both the hand and the shoulder) on the left or right side. Attentional modulations at the hands emerged later and were reduced in the Broad compared to the Narrow attention task, suggesting reduced attentional resources for a wider attentional focus
Behavioural and Electrophysiological evidence for the effect of target-distractor separation in a tactile search task
Full text linkEvidence suggests that the N140cc component of event-related potentials (ERP) observed in tactile search tasks reflects the attentional selection of the target. Here, we investigated whether the target selection processes are affected by the separation between the target and an ipsilateral singleton distractor (singletons delivered to contiguous or non-contiguous fingers of the same hand). In addition, the external distance between search items was varied through posture (splayed or touching fingers). Accuracy improved when target and distractor were delivered to contiguous fingers that were also touching. Regardless of target-distractor separation, the N140cc was larger when the external distance between search-array stimuli decreased (touching fingers). Importantly, a smaller N140cc was observed at reduced target-distractor separations, suggesting a narrower attentional focus for contiguous singletons. These findings reveal that the mechanisms responsible for tactile target selection in the presence of an ipsilateral singleton distractor are fundamentally different from those emerged in vision
Comparing the absolute and relative Simon effects in vision and touch
No full textExisting evidence suggests that the stimulus location is automatically encoded even when it is completely task irrelevant. Both visual and tactile stimuli facilitate the ipsilateral response when presented on the left or right side of space or of the body (absolute or trunk-centred Simon effect, respectively). However, when more than one stimulus is presented within the same side of the space (or the body) a relative spatial code also emerges, giving rise to the relative or hand/centred Simon effect. Thus far this multiple spatial codes created by visual and tactile stimuli have been investigated under very different experimental conditions. The aim of this study was to directly compare the properties of the spatial codes activated by visual and tactile stimuli in a comparable task.
On different blocks of trials, participants responded to the frequency (high/low) of a tactile or visual stimulus using the pedals (right/left) to respond. The stimulus could appear in one of four possible locations, closely matched between visual and tactile stimuli. In touch we observed both a trunk-centred and a hand-centred spatial code, in line with existing results. Surprisingly, no Simon effect emerged in vision. Responses were slower for lateral compared to central stimuli regardless of response location. These results suggest that spatial coding in vision may depend on the type of task relevant stimulus feature
Psychological Traits as predictors of judgements about food
No full textFood is considered a highly significant element for survival and, as a consequence, it is widely used as a stimulus in studies that intend to investigate the processes that are fundamental to human behavior (Lloyd et al,2020; Rangel,2013). In this study, participants were first given a questionnaire for evaluating traits commonly associated with Anorexia and Bulimia, EDI-3 (Garner et al., 1983; Garner et al., 1991; Garner et al., 2004; Giannini et al., 2018) and subsequently were asked to rate food images on 5 different dimensions: Valence (e.g., “How positive / negative would you define the food represented in the image?), Arousal (e.g.,” How much are the sensations you get when looking at the food in the image intense? “), Palatability (e.g.,”How palatable is the food represented in the image for you? “), Healthiness (e.g., "How healthy would you define the food represented in the image?") and Social interaction (e.g.,” How much would you share the food represented in the image? with another person? “). Preliminary data show significantly different evaluations depending on the score obtained at EDI-3.
In general, the goal is to obtain a database of food stimuli validated for experimental research aimed at investigating, for example, the relationship between body representation and food stimuli in healthy participants and with traits attributable to Eating Disorders
The raw and the cooked: an oculomotor investigation of attention to food
No full textIn an eye tracking and pupillometry study, we investigated the factors influencing attentional capture when individuals see food items. We suggest that the two core motivational systems, namely Wanting (i.e.,the desire for food and meal selection) and Liking (i.e.,the subjective pleasure and arousal evoked by food), modulate attentional processes in different ways. Moreover, we hypothesized that two key factors influencing motivation and modulating attentional capture are the preparation of the food (e.g.,raw vs. cooked) and its caloric content (e.g.,high vs. low). To test these hypotheses, we presented 100 food images in two blocks: Multiple images block, where 4 different food items were shown together; and, Single image block, where each food item was presented alone. Importantly, we operationalized Wanting and Liking in terms of fixation durations and pupil
dilation, respectively. Additionally, participants were asked to provide explicit ratings for each food image both in terms of Liking and Wanting. Finally, participants completed the Eating Disorder Inventory-3, allowing us to explore potential relationships between the EDRC scale and our motivational measurements. The findings revealed that both food preparation methods and caloric content
significantly modulated fixation durations and pupil diameter changes. Moreover, we observed that dwell time on a food item emerged as a valid predictor of subjective ratings of ʻWanting’ but not of ʻLiking’. In addition, we observed an inverse relationship between the EDRC scale and fixation durations, suggesting a potential link between unhealthy eating habits and augmented concerning
about the body with attentional processing of food stimuli
Searching on the back:Attentional selectivity in the periphery of the tactile field
Full text linkRecent evidence has identified the N140cc lateralized component of event-related potentials as a reliable index of the deployment of attention to task-relevant items in touch. However, existing ERP studies have presented the tactile search array to participants' limbs, most often to the hands. Here, we investigated distractor interference effects when the tactile search array was presented to a portion of the body that is less lateralized and peripheral compared to the hands. Participants were asked to localize a tactile target presented among distractors in a circular arrangement to their back. The N140cc was elicited contralateral to the target when the singleton distractor was absent. Its amplitude was reduced when the singleton distractor was present and contralateral to the target, suggesting that attention was directed at least in part to the distractor when the singletons are on opposite sides. However, similar N140cc were observed when the singleton distractor was ipsilateral to the target compared to distractor absent trials. We suggest that when target and singleton distractor are ipsilateral, the exact localization of the target requires the attentional processing of all items on the same side of the array, similar to distractor absent trials. Together, these observations replicate the distractor interference effects previously observed for the hands, suggesting that analogous mechanisms guide attentional selectivity across different body parts
Onset and Offset as Determinants of the Simon Effect
No full textWe investigated the presence and the characteristics of the Simon effect for onset and offset targets when these stimuli are randomly intermixed. In Experiment 1, two possible target locations were occupied by an occluder. On onset trials, a target appeared above an occluder, while on offset trials one of the occluders disappeared, revealing the target underneath. In Experiment 2, four stimuli appeared randomly in six possible locations. On onset trials, a new stimulus appeared in an empty location while on offset trials, one of the initial stimuli disappeared. In both experiments, the Simon effect for onset and offset targets was characterized by similar size, time course and sequential modulation, suggesting similar sensorimotor interactions between target and response locations. However, the Simon effect in the current trials was more evident when the same type of target (onset or offset) was repeated on successive trials demonstrating the role of stimulus category in its modulation
Cognitive conflict is an example of action-grounded cognition.
Full text linkThe aim of the present work was to show that cognitive conflict, an issue that has been widely studied within theboundaries of the classical cognitive approach, is a clear example of higher order cognition tied to perceptionand action. Examples of how the cognitive conflict arising from spatial correspondence tasks is highly groundedin body attributes and in environmental/situational factors are provided. Spatial performance is stronglymodulated by handedness, prior experience and by social factors. In addition, in two experiments empiricalfindings are reported showing that the spatial correspondence effect is a function of the location of the dynamicevent even when target location is in the opposite position. These results point to the notion that spatialperformance is refractory from the intervention of higher order cognition
Empathy as a predictor of peripersonal space: Evidence from the crossmodal congruency task
Full text linkTo investigate whether individual differences in Empathy predict the characteristics of Peripersonal Space (PPS) representations, we asked participants to complete the IRI questionnaire and a visuo-tactile crossmodal congruency task (CCT) as an index of PPS. In the CCT, they responded to the elevation of a tactile target while ignoring a visual distractor presented at the same (i.e. congruent) or different (i.e. incongruent) elevation. The target-distractor distance was also manipulated in depth, with visual distractors randomly presented at near, middle or far locations (0 cm, 25 cm or 50 cm). The near and middle crossmodal congruency effects (CCE) were inversely related to participants’ scores on the Empathic Concern sub-scale (EC). Furthermore, the slope of participants’ CCE across locations was related to EC scores, with flatter slopes for higher EC individuals. Thus, higher EC individuals showed reduced visuo-tactile integration responses within PPS and a reduced differentiation between PPS and extra-personal space (EPS)
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