Self-reference in action: Arm-movement responses are enhanced in perceptual matching

An identity-irrelevant discrimination task reveals familiarity-advantage in face perception and no self-advantage in voice perception

Whether or not self-face and self-voice are processed more accurately than others' remains inconclusive. Most previous studies asked participants to judge the presented stimulus as their own or as others', and compared response accuracy to discuss self-advantage. However, it is possible that participants responded correctly in the "other" trials not by identifying "other" but rather by rejecting "self." The present study employed an identity-irrelevant discrimination task, in which participants detected the odd stimulus among the three sequentially presented stimuli. We measured the discrimination thresholds for the self, friend, and stranger conditions. In Experiment 1 (face), the discrimination thresholds for self and friends' faces were lower than those for strangers' faces. This suggests that self-face may not be perceived as special or unique, and facial representation may become more accurate due to increased familiarity through repetitive exposure. Whereas, in Experiment 2 (voice), the discrimination thresholds did not differ between the three conditions, suggesting that the sensitivity to changes is the same regardless of identity. Overall, we found no evidence for self-advantage in identification accuracy, as we observed a familiarity-advantage rather than self-advantage in face processing and a null difference in voice processing.

You do you: susceptibility of temporal binding to self-relevance

The self-prioritization effect suggests that self-relevant information has a processing advantage over information that is not directly associated with the self. In consequence, reaction times are faster and accuracy rates higher when reacting to self-associated stimuli rather than to other-related stimuli (Sui et al., Journal of Experimental Psychology: Human Perception and Performance 38:1105-1117, 2012). This spurs the assumption that self-associated action-effects should also be perceived earlier than other-related outcomes. One way to measure this is temporal binding. Previous research indeed showed that the perceived temporal interval between actions and self-associated outcomes was reduced compared to friend- and other-associated outcomes. However, the employed method (interval estimations) and several experimental design choices make it impossible to discern whether the perceived shortening of the interval between a keypress and a self-relevant outcome is due to a perceptual shift of the action or of the action-effect or both. Thus, we conducted four experiments to assess whether temporal binding can indeed be modulated by self-relevance and if so where this perceptual bias is located. The results did not support stronger temporal binding for self- vs other-related action-effects. We discuss these results against the backdrop of the attentional basis of self-prioritization and propose directions for future research.

Testing the modulation of self-related automatic and others-related controlled processing by chronotype and time-of-day

We assessed whether self-related automatic and others-related controlled processes are modulated by chronotype and time-of-day. Here, a shape-label matching task composed of three geometrical shapes arbitrarily associated with you, friend, and stranger was used. Twenty Morning-types, and twenty Evening-types performed the task at the optimal and non-optimal times of day (i.e., 8 AM, or 8:30 PM). Morning-types did not exhibit noticeable synchrony effects, thus proving the better adaptation of these participants to non-optimal moments of the day as compared to Evening-types. Contrary to our predictions regarding the absence of automatic-processing modulation and the presence of controlled-processing influences by time-of-day, we found an influence on self-related but not others-related processing only in Evening-type participants. Although brain structures are not directly tackled, we argue that such modulation may be due to the dependence of the activation of the ventromedial prefrontal cortex (VMPFC), an essential component of the self-attention network on circadian rhythms.

Self-prioritization effect in the attentional blink paradigm: Attention-based or familiarity-based effect?

The self-prioritization effect (SPE) refers to the advantage in processing stimuli associated with oneself. Here, we addressed the SPE in an attentional blink (AB) task. In Experiment 1, shapes associated to you, friend, or stranger served as T1, and letter X as T2. The AB effect was larger for you than the other label conditions, and larger for friend condition than for stranger condition. We suggest that self-associated shape increased its perceptual salience, producing greater attentional capture. In Experiment 2 participants trained with a shape-label matching task to increase familiarity with the shape-label associations before performing the AB task. The difference between friend and stranger conditions disappeared, suggesting that the difference between the two conditions observed in Experiment 1 was mainly due to differences in familiarity or frequency of use. Importantly, the advantage of you over friend and stranger conditions remained, suggesting that the SPE is a genuine effect.

To see or not to see: the parallel processing of self-relevance and facial expressions

The self, like the concept of central "gravity", facilitates the processing of information that is directly relevant to the self. This phenomenon is known as the self-prioritization effect. However, it remains unclear whether the self-prioritization effect extends to the processing of emotional facial expressions. To fill this gap, we used a self-association paradigm to investigate the impact of self-relevance on the recognition of emotional facial expressions while controlling for confounding factors such as familiarity and overlearning. Using a large and diverse sample, we replicated the effect of self-relevance on face processing but found no evidence for a modulation of self-relevance on facial emotion recognition. We propose two potential theoretical explanations to account for these findings and emphasize that further research with different experimental designs and a multitasks measurement approach is needed to understand this mechanism fully. Overall, our study contributes to the literature on the parallel cognitive processing of self-relevance and facial emotion recognition, with implications for both social and cognitive psychology.

Object coding in peripersonal space depends on object ownership

Previous studies have shown that objects located in the peripersonal space (PPS) receive enhanced attention, as compared with extrapersonal space (EPS), However, most objects in the environment belong to someone in particular and how object ownership influences object coding in relation to PPS representation is still unclear. In the present study, after having chosen their own mug, participants performed a reachability judgement task of self-owned and other-owned mugs presented at different distances while facing a virtual character. This task was followed, on each trial, by a localisation task in which participants had to indicate where the mug, removed from view, was previously located. The two tasks were separated by a 900-ms visual mask during which the virtual character was unnoticeably shifted by 3° to evaluate the spatial frame-of-reference used. The results showed that self-owned mugs were processed faster than other-owned mugs, but only when located in the PPS. Furthermore, reachability judgements were biased for self-owned mugs, leading to an extension of the PPS representation, especially for participants with a high score on the fantasy scale of Interpersonal Reactivity Index (IRI). Finally, the virtual character shift altered the localisation performance but only for the distant mugs, suggesting a progressive shift from egocentric to allocentric frame-of-reference when moving from the PPS to EPS, irrespective of object ownership. Overall, our data reveal that the representations of ownership and PPS interact to facilitate the processing of manipulable objects, to an extent that depends on individual sensitivity to the social presence of others.

On screen experiment showed that becoming a parent for the first time shifted people's priorities from themselves to their infant at 1 year of age

AIM

This study used a screen-based perceptual matching task to see how non-parents, people trying to get pregnant, and those who had given birth prioritised shapes and labels relating to self or infant conditions.

METHODS

The study took place at Aarhus University Hospital in Denmark from December 2016 to November 2021. Recruitment methods included family planning clinics, social media, online recruitment systems and local bulletin boards. The modified perceptual matching task linked five shapes to five labels, including self and infant.

RESULTS

We found that 67 males and females with a mean age of 24.4 ± 3 years, who had no plans to become parents in the near future, reacted faster and more accurately to self-shapes and labels (p < 0.001), which validated the experiment. The 56 participants aged 27.1 ± 4.4 years who were actively trying to become parents showed no statistically significant prioritisation. A subset of 21 participants aged 28.7 ± 4.4 years showed faster response times to infant than self-shapes and labels 1 year after giving birth (p < 0.001).

CONCLUSION

Healthy first-time parents showed faster reactions to infant than self-conditions 1 year after giving birth, in contrast to the other two groups.

Self-prioritization with unisensory and multisensory stimuli in a matching task

A shape-label matching task is commonly used to examine the self-advantage in motor reaction-time responses (the Self-Prioritization Effect; SPE). In the present study, auditory labels were introduced, and, for the first time, responses to unisensory auditory, unisensory visual, and multisensory object-label stimuli were compared across block-type (i.e., trials blocked by sensory modality type, and intermixed trials of unisensory and multisensory stimuli). Auditory stimulus intensity was presented at either 50 dB (Group 1) or 70 dB (Group 2). The participants in Group 2 also completed a multisensory detection task, making simple speeded motor responses to the shape and sound stimuli and their multisensory combinations. In the matching task, the SPE was diminished in intermixed trials, and in responses to the unisensory auditory stimuli as compared with the multisensory (visual shape+auditory label) stimuli. In contrast, the SPE did not differ in responses to the unisensory visual and multisensory (auditory object+visual label) stimuli. The matching task was associated with multisensory ‘costs’ rather than gains, but response times to self- versus stranger-associated stimuli were differentially affected by the type of multisensory stimulus (auditory object+visual label or visual shape+auditory label). The SPE was thus modulated both by block-type and the combination of object and label stimulus modalities. There was no SPE in the detection task. Taken together, these findings suggest that the SPE with unisensory and multisensory stimuli is modulated by both stimulus- and task-related parameters within the matching task. The SPE does not transfer to a significant motor speed gain when the self-associations are not task-relevant.

Self-Prioritization Effect in Children and Adults

Self-related information is processed with priority, an effect known as the self-prioritization effect (SPE). Recent studies on SPE show enhanced cognitive processing of the newly learned self-association compared to non-self (such as mother, friend, and stranger) associations among younger and older adults. However, developmental influences on the magnitude of SPE remain poorly understood. In order to examine the developmental impacts on the SPE, in the present study, we recruited participants ranging from 9–22 years of age and divided them into three age groups: older children (age 9–13), teenagers (age 14–17), and young adult (age 18–22) and compared their performance in the matching judgment task. Our results show more significant bias toward self than mother, friend, or stranger condition in all the three age groups, showing robust SPE in the 9-22-year-old age group. We also observed a more significant bias toward mother-association than friend and stranger-association in all the age groups showing an enhanced bias toward mother. Our study extends the SPE in older children and teenagers and shows that SPE remains robust and stable throughout childhood.

The thickness of the ventral medial prefrontal cortex predicts the prior-entry effect for allocentric representation in near space

Neuropsychological studies have demonstrated that the preferential processing of near-space and egocentric representation is associated with the self-prioritization effect (SPE). However, relatively little is known concerning whether the SPE is superior to the representation of egocentric frames or near-space processing in the interaction between spatial reference frames and spatial domains. The present study adopted the variant of the shape-label matching task (i.e., color-label) to establish an SPE, combined with a spatial reference frame judgment task, to examine how the SPE leads to preferential processing of near-space or egocentric representations. Surface-based morphometry analysis was also adopted to extract the cortical thickness of the ventral medial prefrontal cortex (vmPFC) to examine whether it could predict differences in the SPE at the behavioral level. The results showed a significant SPE, manifested as the response of self-associated color being faster than that of stranger-associated color. Additionally, the SPE showed a preference for near-space processing, followed by egocentric representation. More importantly, the thickness of the vmPFC could predict the difference in the SPE on reference frames, particularly in the left frontal pole cortex and bilateral rostral anterior cingulate cortex. These findings indicated that the SPE showed a prior entry effect for information at the spatial level relative to the reference frame level, providing evidence to support the structural significance of the self-processing region.

Self-prioritization is supported by interactions between large-scale brain networks

Resting-state functional magnetic resonance imaging (fMRI) has provided solid evidence that the default-mode network (DMN) is implicated in self-referential processing. The functional connectivity of the DMN has also been observed in tasks where self-referential processing leads to self-prioritization (SPE) in perception and decision-making. However, we are less certain about whether (i) SPE solely depends on the interplay within parts of the DMN or is driven by multiple brain networks; and (ii) whether SPE is associated with a unique component of interconnected networks or can be explained by related effects such as emotion prioritization. We addressed these questions by identifying and comparing topological clusters of networks involved in self-and emotion prioritization effects generated in an associative-matching task. Using network-based statistics, we found that SPE controlled by emotion is supported by a unique component of interacting networks, including the medial prefrontal part of the DMN (MPFC), Frontoparietal network (FPN) and insular Salience network (SN). This component emerged as a result of a focal effect confined to few connections, indicating that interaction between DMN, FPC and SN is critical to cognitive operations for the SPE. This result was validated on a separate data set. In contrast, prioritization of happy emotion was associated with a component formed by interactions between the rostral prefrontal part of SN, posterior parietal part of FPN and the MPFC, while sad emotion reveals a cluster of the DMN, Dorsal Attention Network (DAN) and Visual Medial Network (VMN). We discussed theoretical and methodological aspects of these findings within the more general domain of social cognition.

Self-prioritization depends on assumed task-relevance of self-association

We conducted three experiments to test the effect of assumed task-relevance of self-association on the self-prioritization effect (SPE). Participants were first performing the standard matching task, and then a pseudo-word matching task, in which familiar labels from the standard task were replaced with pseudo-words. In the pseudo-words task, the association between stimuli and the self was, in fact, task-irrelevant. Learning instructions were varied to make participants believe that the self-association was task-relevant (Experiments 1 and 3) or task-irrelevant (Experiment 2). In Experiment 1, we told participants that geometrical shapes represent specific identities (self, friend, none) and pseudo-words' meanings reflect each of these identities to make participants believe that semantic associations of pseudo-words were task-relevant. In this experiment, a SPE was present in the pseudo-words task. Experiment 2 was identical to Experiment 1, but participants were told to form association pairs between pseudo-words and shapes, and not pseudo-words and identities. Thus, because the matching task presented only shapes and pseudo-words, participants were led to correctly believe that associations were task-irrelevant. Under these conditions, we did not observe a SPE in the pseudo-words task. Finally, in Experiment 3, participants were told that pseudo-words are "paired with" identities, making their relations with identities weaker than in Experiment 1, but still task-relevant. The SPE in the pseudo-word task reappeared. Together, the results suggest that a SPE can be observed in the absence of any stimuli with established self-associations, but only if self-associations are represented as task-relevant.

The Self-Prioritization Effect: Self-referential processing in movement highlights modulation at multiple stages

A wealth of recent research supports the validity of the Self-Prioritization Effect (SPE)—the performance advantage for responses to self-associated as compared with other-person-associated stimuli in a shape–label matching task. However, inconsistent findings have been reported regarding the particular stage(s) of information processing that are influenced. In one account, self-prioritization modulates multiple stages of processing, whereas according to a competing account, self-prioritization is driven solely by a modulation in central-stage information-processing. To decide between these two possibilities, the present study tested whether the self-advantage in arm movements previously reported could reflect a response bias using visual feedback (Experiment 1), or approach motivation processes (Experiments 1 and 2). In Experiment 1, visual feedback was occluded in a ballistic movement-time variant of the matching task, whereas in Experiment 2, task responses were directed away from the stimuli and the participant’s body. The advantage for self in arm-movement responses emerged in both experiments. The findings indicate that the self-advantage in arm-movement responses does not depend on the use of visual feedback or on a self/stimuli-directed response. They further indicate that self-relevance can modulate movement responses (predominantly) using proprioceptive, kinaesthetic, and tactile information. These findings support the view that self-relevance modulates arm-movement responses, countering the suggestion that self-prioritization only influences central-stage processes, and consistent with a multiple-stage influence instead.

Multisensory Perceptual Biases for Social and Reward Associations

Linking arbitrary shapes (e.g., circles, squares, and triangles) to personal labels (e.g., self, friend, or stranger) or reward values (e.g., £18, £6, or £2) results in immediate processing benefits for those stimuli that happen to be associated with the self or high rewards in perceptual matching tasks. Here we further explored how social and reward associations interact with multisensory stimuli by pairing labels and objects with tones (low, medium, and high tones). We also investigated whether self and reward biases persist for multisensory stimuli with the label removed after an association had been made. Both high reward stimuli and those associated with the self, resulted in faster responses and improved discriminability (i.e., higher d’), which persisted for multisensory stimuli even when the labels were removed. However, these self- and reward-biases partly depended on the specific alignment between the physical tones (low, medium, and high) and the conceptual (social or reward) order. Performance for reward associations improved when the endpoints of low or high rewards were paired with low or high tones; meanwhile, for personal associations, there was a benefit when the self was paired with either low or high tones, but there was no effect when the stranger was associated with either endpoint. These results indicate that, unlike reward, social personal associations are not represented along a continuum with two marked endpoints (i.e., self and stranger) but rather with a single reference point (the self vs. other).

Self-prioritization during stimulus processing is not obligatory

An emerging literature has suggested that self-relevance automatically enhances stimulus processing (i.e., the self-prioritization effect). Specifically, during shape-label matching tasks, geometric shapes associated with the self are identified more rapidly than comparable stimuli paired with other targets (e.g., friend, stranger). Replicating and extending work that challenges the putative automaticity of this effect, here we hypothesized that self-relevance facilitates stimulus processing only when task sets draw attention to previously formed shape-label associations in memory. The results of a shape-classification task confirmed this prediction. Compared to shapes associated with a friend, those paired with the self were classified more rapidly when participants were required to report who the stimulus denoted (i.e., self or friend). In contrast, self-relevance failed to facilitate performance when participants judged either what the shape was (i.e., triangle or square, diamond or circle) or where it was located on the screen (i.e., above or below fixation). These findings further elucidate the conditions under which self-relevance does-and does not-influence stimulus processing.

Stranger to my face: Top-down and bottom-up effects underlying prioritization of images of one's face

Recent studies suggest that we rapidly and effortlessly associate neutral information with the self, leading to subsequent prioritization of this information in perception. However, the exact underlying processes behind these effects are not fully known. Here, we focus specifically on top-down and bottom-up processes involved in self-prioritization, and report results from three experiments involving face detection, using a sequential match-non-match task. Across the three experiments we asked participants to associate an unfamiliar face with the self (Experiment 1), to associate one's face with a stranger's name (Experiment 2), and to establish both associations simultaneously (Experiment 3). We found that while participants showed evidence of bottom-up prioritization of their real faces, they did not show such an effect for self-associated strangers' faces. However, the participants showed a robust self-related top-down effect; when presented with a self-related cue, they were later faster at classifying both subsequent correct and incorrect targets. Together, our results suggest that self-prioritization is underpinned by distinct top-down and bottom-up processes. We discuss our findings in the context of the proposal that the self acts as an "integrative glue", and suggest an interpretation of our results within the framework of predictive coding.

Self-prioritization of fully unfamiliar stimuli

Recently, Sui and colleagues introduced an experimental task to investigate prioritization of arbitrary stimuli associated with the self. They demonstrated that after being told to associate three identities (self, friend, stranger) with three arbitrary stimuli (geometrical shapes), participants were faster in a perceptual matching task to recognise matching pairs of self-associated shape with self-label, than respective friend or stranger-related pairings. They interpreted this as evidence that a brief self-association is sufficient to facilitate processing of previously neutral stimuli. However, in the matching trials of the self-prioritization task, participants are processing not only self-associated arbitrary stimuli but also familiar verbal labels with an established meaning. Therefore, the self-advantage may be caused by familiarity of the labels, rather than self-association of the shapes. To test whether self-prioritization can be elicited in a task employing exclusively neutral stimuli, we asked participants to associate avatar faces with three identities (self, name of best friend, and stranger) and replaced labels with unfamiliar abstract symbols that were associated to the words (you, friend, stranger) before the actual experiment started. The results presented the usual pattern of self-prioritization showing that this effect does not critically depend on the presence of familiar labels and that it can be elicited in the absence of any familiar stimuli.