The ‘self’ is a key concept in the study of human social cognition that has fascinated researchers across many disciplines over the years. In an attempt to clarify the ‘special’ nature of the self [1, 2], several studies demonstrated how the relevance or relatedness to the self can considerably affect information processing . As a matter of fact, individuals are inclined to process stimuli that are self-related in a favored fashion, eliciting a cognitive advantage commonly defined as the ‘egocentric bias’ or ‘self-bias’ . This human predisposition leads individuals to memorize, learn and detect self-relevant stimuli more efficiently . In order to assess to what extent the self-relatedness of a certain stimulus influences an individual’s performance, the self-bias has been operationalized in a wide range of empirical paradigms [6, 7, 8]. A multitude of behavioral measures has been employed to investigate the magnitude of self-bias on distinct cognitive domains, such as perception, memory and attention [3, 4]. Nevertheless, it is still unclear which aspects of cognition are mostly affected by the self-bias, and how the self-bias in one domain might relate to the self-bias in another domain. Distinct measures of the self-bias might all draw upon a ‘common’, unitary self-representation; conversely, different aspects of self-representation may underlie distinct measures.
An illustrative example of one of these self-bias measures is the shape-label matching task [9, 10], originally developed to test the effect of novel, transitory self-associations on perception. In this paradigm, participants are first trained to associate geometric shapes with specific labels, indicating either themselves (e.g., ‘you’), a familiar other (e.g., ‘friend’) or an unfamiliar other (e.g., ‘stranger’). Subsequently, participants are presented with either the original shape-label pairings, or new, re-paired associations. The participant’s task is to determine whether the shape matches the label or not on each trial. Results indicate a robust advantage for matching combinations of self-associated stimuli as compared to both familiar and unfamiliar other-associated stimuli. In addition, when the present paradigm was used, self-related associations were found to be less affected by visual degradation than other-related ones (i.e., responses for self-related stimuli were less influenced by contrast reduction ), suggesting that self-reference exerts an influence on early-stage, low-level perceptual processing.
In studies exploring the self-bias on memory, there have also been consistent observations of a cognitive advantage in recalling self-related over other-related material . This self-bias effect has originally been referred to as the ‘self-reference effect’ (i.e., SRE ), which has most often been measured with the well-established trait-adjectives paradigm [12, 13, 14]. In this paradigm, participants are asked to judge adjectives in relation to either themselves or to others during a study phase. Another self-processing measure in the memory domain is the ownership task , where participants are required to sort objects into self- or other-owned sets during a study phase. In both paradigms, participants later perform a surprise recognition task, which includes the already-seen adjectives/objects as well as distracters, and they are asked to assess whether a specific item has already been presented in the first ‘encoding phase’ or not. Findings from such studies reveal a significantly better memory for objects or trait adjectives that have previously been related to the self as compared to others, and this considerable advantage (i.e., SRE) was found both in typically developing children  as well as in adults .
A third context in which the preference for self- over other-related information has been discussed is in the attentional domain. Cognitive processing of stimuli such as participants’ own name has been examined using the attentional blink paradigm . This task entails a phenomenon consisting in a decreased ability to detect a second target following a first target in a rapid serial visual presentation (RSVP) stream . When participants are presented with their own name as the second target compared with a close other’s name, the attentional blink is significantly reduced . Similarly, both repetition blindness – a reduced accuracy in reporting the appearance of a stimulus when repeated  – and inattentional blindness – an inability to detect an unattended, yet visible stimulus  – were found to be diminished for self-referential information [21, 22]. An attentional advantage for self-related material also persistently emerges in the visual search task . Specifically, Yang and colleagues  instructed participants to detect either their own, a familiar, or a famous name in an array of distracter names. When searching for their own name, participants showed significantly higher accuracy and faster reaction times than when searching for either familiar or famous names.
It should be noted that thus far, the magnitude of distinct self-bias effects has mostly been investigated in the context of separate studies, making it harder to relate findings from different paradigms to each other. There is a long-established notion that self-reference acts as an ‘integrative hub for information processing’ , evenly impacting all cognitive domains. However, this notion has recently been questioned, as it may also be that self-reference affects cognition differently depending on the cognitive domain under investigation: instead of unidimensional and homogeneous, its effects may be diversified and multifaceted. To address this question, a direct comparison of the different self-biases within one and the same sample is required. To our knowledge, only one study directly compared the self-bias effects across cognitive domains within the same sample: Nijhof and colleagues  administered two self-processing measures – respectively in the context of attention and perception – within the same experimental procedure, and found no evidence for a common mechanism that underlies the self-biases across these domains. Such findings endorse a view of the self-bias as a heterogeneous phenomenon that does not draw upon a shared, underlying self-representation.
Further support for a non-unitary impact of the self-bias on cognition comes from the body of literature that has investigated self-bias effects in individuals with autism. Regardless of the cognitive domain under study, it is believed that the self-bias fosters social competence, as a stronger sense of self is thought to help one build a better model of the social world [5, 25, 26]. Not surprisingly, an altered self-bias has been argued to lead to social impairments by impeding the understanding of other people’s emotions, intentions or beliefs [19, 27, 28]. This led to a growing number of studies investigating self-processing in autism. Current findings are however inconsistent, with autism-related reduced self-bias effects found for some of the aforementioned paradigms, but not for others. For instance, the self-bias on the shape-label matching task showed no significant association with autistic traits in neurotypicals , and its magnitude did not differ between autistic adults and matched controls . As for the attentional domain, Nijhof and colleagues  observed no significant correlation between autistic traits and the self-bias magnitude in the context of the attentional blink paradigm. In contrast, in the memory domain, the self-bias effect was found to be absent or significantly reduced in autistic children , adolescents  and adults [14, 31, 32]. Nevertheless, more recent research challenged these results, suggesting no significant relation between the self-bias magnitude in the memory domain and autistic traits, in both neurotypicals as well as individuals with autism [33, 34]. In summary, despite some evidence pointing out altered self-processing in individuals with autism, it is clear that findings are still mixed. Most importantly, this inconsistency of findings provides further support for a non-unitary impact of the self-bias on cognition, which may in turn explain the lack of overlap among studies investigating such effects in autism.
When confronted with such conflicting results, one could indeed argue that the inconsistency of the current findings relates to the lack of convergence with regard to the type of self-representations under investigation . It has been suggested that early-stage processing of self-referential material (e.g., tagging an item as ‘self-related’) may be intact in autism, while late-stage self-referential processing (e.g., assessing whether an adjective applies to the self or not) may be impaired. This distinction between early- and late-stage processing of self-related information resembles James’ conceptualization of first and second-order self-representations : stimuli can be labelled as merely self-related (first-order processing, e.g. “Self = circle”) or can in turn be processed as the object of one’s own thought (second-order processing, e.g., “Does the word ‘intelligent’ describe me?”). In this respect, the impact of self-relevance might change considerably depending on the cognitive process it affects.
To date, the aforementioned investigation conducted by Nijhof and colleagues  constitutes the only attempt to administer distinct self-bias measures across cognitive domains in a common sample of participants. Moreover, the way different measures of self-processing relate to each other needs additional investigation in both neurotypical and autistic populations . A more exhaustive knowledge of the mechanisms underlying the self-bias in neurotypicals could improve our understanding of how this effect might be altered in individuals with autism. Furthermore, overall conclusions on the impact of self-relatedness on cognition have generally been drawn on the basis of relatively small samples, that were possibly lacking sufficient statistical power [15, 22, 32]. Under-powered studies risk producing a larger quantity of false negatives than high-powered studies , and tend to report statistically significant findings which actually have a relatively low likelihood of reflecting authentic effects . Using adequately powered samples to study self-processing and its relation to autistic traits has therefore become imperative.
In light of the above, the main aim of the present study is to investigate self-bias effects across distinct cognitive domains, by administering and comparing three self-processing measures, i.e., the shape-label matching task (perceptual domain), the trait adjectives task (memory domain), and the visual search task (attentional domain), within the same experimental procedure. The current investigation has two foremost goals. The primary goal is to explore whether self-biases in attention, memory and perception are related, emerging as a result of a shared mechanism underlying egocentric biases across cognitive domains, or instead consist in distinct effects, that are unrelated to each other (as was found for the self-biases on the shape-label matching task and the attentional blink task ). The secondary goal is to investigate the associations between different self-processing measures and questionnaires assessing autistic traits to provide a better understanding of how self-bias effects might be linked to autism symptomatology. Although the only previous study  reported the lack of a shared mechanism underlying self-bias effects, the current study employs distinct self-processing paradigms from those used in the study of Nijhof and colleagues , consisting both of higher-order self-processing (trait adjectives task), attentional self-processing (visual search task), and low-level perceptual self-processing (shape-label matching task). As a result, both converging and diverging self-bias effects may be expected. Furthermore, a dimensional approach will be applied exploring possible associations between the magnitude of different self-bias effects and autistic traits. It has been argued that autism-related characteristics are continuously distributed across the neurotypical population . The dimensional approach is indeed considered to be informative of relevant features in autism, and has successfully been adopted by previous studies (see, e.g., ). Despite reports of a link between reduced self-bias and autism, findings are not consistent: investigating self-bias across different domains within the same sample may provide more clarity.