**2. Implicit theory of mind reasoning in Autism Spectrum Disorders: Insights from the analysis of eye movements**

In the last years, eye tracking gained massive popularity in ASD research [17]. This method aims at linking gaze patterns to cognitive processes [18]. Tracking eye movements while watching social stimuli on a computer screen is especially suited for ASD research because it is independent of verbal abilities of the participants and avoids possible aversively experienced social interactions with the experimenter during the test.

Senju, Southgate, White and Frith [19] were the first to combine eye tracking and an implicit ToM task in an experiment with individuals with ASD and found a striking dissociation between explicit and implicit ToM reasoning: Participants with Asperger syndrome did not differ from a neurotypical control group in their performance on explicit ToM tasks. However, their eye movements in the implicit false belief task revealed an intriguing group difference. In this task, just like in the explicit version, the participants watched an agent who did not witness the transfer of a ball from one box to another and thus has a false belief about its location. However, in the subsequent test phase, participants were not explicitly asked where the agent would search for the ball (in the now empty box), but eye movements in anticipation of the following reaching action of the agent were measured. This allowed for assessing whether participants kept track of the agent's belief about the object's location without explicitly asking for it. Whereas neurotypical adults correctly anticipated that the agent would search for the ball in the now empty box, individuals with ASD lacked this anticipation of the false-belief congruent behavior.

Senju et al.'s [19] groundbreaking findings corroborated two-systems accounts of ToM. Furthermore, the findings suggest that while the explicit ToM deficit can be alleviated by compensatory strategies [20], the implicit ToM reasoning deficit is sustained and not address‐ able with learning strategies [21].

The following section reviews recent empirical findings on implicit and explicit ToM in ASD to shed light on the cognitive characteristics of ToM reasoning in ASD. In the beginning we provide a short rationale of why and how eye movements can be utilized to draw conclusions on the cognitive nature of ToM reasoning. Subsequently, we review the fast growing body of evidence on implicit ToM reasoning in ASD in the light of two-systems accounts. We will particularly discuss the fit of recent empirical findings with the notion of a sustained implicit ToM deficit which cannot be compensated for.

#### **2.1. What eye movements reveal about ToM reasoning**

deficits, since experimental situations do not pose the kinds of stressful demands on individ‐ uals with ASD that real-life social situations do. This may be one reason for the failure of ToM-

In the last ten years, new methods, relying on spontaneous and implicit ToM processing have been productively used to further investigate the social and cognitive impairments in ASD. These methods were first used in infant research; infants and young children under the age of about 4 years, like patients with ASD, fail explicit ToM tasks, but nevertheless show a spon‐ taneous sensitivity to others' mental states in looking-time, eye-tracking, and interactive tasks [10]. An implicit ToM appears to developmentally precede an explicit one (two-systems

Explicit ToM reasoning describes the ability to deliberately consider others' mental states and provide reasons in order to explain their behavior ("Sally will look for the ball in the basket because she falsely believes it is still in there"; see [12]). This form of ToM reasoning acts consciously, can be flexibly employed in various situations, and is cognitively demanding. Explicit ToM tasks, like the Sally-Anne task, test this ability by assessing verbal responses to

Implicit ToM reasoning refers to the spontaneous sensitivity to others' mental states without the need to deliberately reflect on them. It is supposed to work fast, unconsciously, but rigidly. Implicit ToM tasks, clever nonverbal versions of the Sally-Anne task, assess the participant's gaze in anticipation of the protagonist's belief-based behavior as an indicator of implicit ToM reasoning (e.g., [13]). In the first section of the present chapter, we review the research on

Not all spontaneous ToM processing is implicit. The spontaneous use of mental state terms in everyday conversations is one of the first signs for an explicit understanding of mental states in child development, with talk about volitional states and emotions, beginning in the second year of life and preceding cognitive language by over one year [14]. While some usages of mental state terms serve conversational functions without genuine reference to mental states [14], there is evidence for specific relations between cognition terms and perspective taking abilities [15] and for predictive relations between preverbal communicative abilities and mental state language [16] in child development. Since the study of mental state language in ASD poses fewer restrictive task demands than experimental ToM tasks, it may add to our understanding of mental state representation in ASD in important ways. The second part of

**2. Implicit theory of mind reasoning in Autism Spectrum Disorders:**

In the last years, eye tracking gained massive popularity in ASD research [17]. This method aims at linking gaze patterns to cognitive processes [18]. Tracking eye movements while watching social stimuli on a computer screen is especially suited for ASD research because it

the direct question for the protagonist's mental state and belief-based behavior.

based interventions to enhance real-world social competencies [9].

accounts; [11]).

114 Autism Spectrum Disorder - Recent Advances

implicit ToM processing in ASD.

the present chapter focuses on this line of research.

**Insights from the analysis of eye movements**

In the past years the analysis of gaze behavior became more and more popular in ToM research. The investigation of eye movements aims to relate gaze patterns to cognitive processes. In twodimensional scenes two basic types of eye movements occur: First, fixations, the persistence of the center of sharp vision for a specific amount of time on an item in the scene; second, saccades, jump-like movements of the eyes from one fixation to the next. Since visual infor‐ mation is only obtained during fixations, fixation patterns can very precisely reveal what visual information is taken into account at a given point in time [18]. On the basis of such data, conclusions can be drawn on the cognitive processes that underlie visual search [22]. Eye tracking systems provide an abundance of precise information about the focus of visual attention in time and space. These systems record gaze data from one or both eyes, providing x-and y-coordinates of the fixated location of a screen. This happens on a millisecond level with a spatial resolution of around 0.1° of visual angle, depending on the system, sampling rate, and accuracy of calibration. But how can this method tell us something about ToM reasoning?

In the 1990s eye movements started to be employed in ToM research. Clements and Perner [13] investigated whether eye movements in the false belief task reveal children's understanding of others' mental states. Video recordings of children's looking behavior were decoded and raters judged which of the two locations in a false belief task the child was looking at. Although the 3-year-olds provided a wrong answer, supporting the claim that children before 4 years of age are not able to understand false beliefs [23], their looking patterns suggested sensitivity to the character's false belief. This pioneering eye tracking work started a line of research and a heated debate on when and how children are able to attribute mental states [24]. Furthermore, this study showed that the analysis of eye movements might be an interesting approach to indicate ToM reasoning.

Psycholinguistic research employing the visual world paradigm [25] showed that eye move‐ ments are influenced by mental representations. An example of how this paradigm can be used comes from Altmann and Kamide [26]: In their experiment they presented a scene depicting a woman and table, for example. A bottle and a glass were on the floor. Subjects listened to the sentence "The woman will put the glass on the table. Then, she will pick up the bottle, and pour the wine carefully into the glass." This scene either remained unchanged (experiment 1) or it was completely removed before the sentence was spoken (experiment 2). Eye movements towards the table, or towards the location where the table had been, after hearing "pour" revealed an influence of the mental representation of the glass (according to the sentence it should now be on the table) on fixation patterns.

If one's own current and past mental representations of an object's locations in a scene influence eye movements, they might also be sensitive to the processing of another's mental represen‐ tation. Adapting the visual world paradigm Ferguson and Breheny [27] reported evidence that eye movements indeed provide insight into the real-time processing of others' mental states. In an interactive video task, a participant and a confederate watched movie clips of an object that was put into one of two boxes and subsequently was pulled out of it again. After that the object was either put back into the same place or transferred to the other box. In half oft he trials the confederate did not witness whether there was a transfer or not. Thus, unlike the participant, the confederate was unsure about the final location of the object. At the end of the trial the confederate verbally described the situation as in the following scheme: "The [object] is in box [A/B]". The participants' fixations on the boxes were linked to the onsets of critical words in this verbal description. This analysis revealed a tendency to fixate the box in which the object actually ended up. Only when the confederate did not witness the object transfer, this gaze pattern changed towards an increased probability to anticipatorily fixate the alternative box, which was empty, but the confederate might have assumed that it could have been in there. This suggests that participants took into account what the other had or had not seen.

First, this finding demonstrates that neurotypical adults are rapidly and spontaneously sensitive to other's mental states during communication. Second, this study shows that eye movements are a sensitive indicator of spontaneous and "online" ToM reasoning without explicitly asking for mental states of others. Thus far, the fast growing field of eye tracking research on ToM has employed a number of paradigms and measures (Box 1 provides an overview of hitherto used eye movement measures).

rate, and accuracy of calibration. But how can this method tell us something about ToM

In the 1990s eye movements started to be employed in ToM research. Clements and Perner [13] investigated whether eye movements in the false belief task reveal children's understanding of others' mental states. Video recordings of children's looking behavior were decoded and raters judged which of the two locations in a false belief task the child was looking at. Although the 3-year-olds provided a wrong answer, supporting the claim that children before 4 years of age are not able to understand false beliefs [23], their looking patterns suggested sensitivity to the character's false belief. This pioneering eye tracking work started a line of research and a heated debate on when and how children are able to attribute mental states [24]. Furthermore, this study showed that the analysis of eye movements might be an interesting approach to

Psycholinguistic research employing the visual world paradigm [25] showed that eye move‐ ments are influenced by mental representations. An example of how this paradigm can be used comes from Altmann and Kamide [26]: In their experiment they presented a scene depicting a woman and table, for example. A bottle and a glass were on the floor. Subjects listened to the sentence "The woman will put the glass on the table. Then, she will pick up the bottle, and pour the wine carefully into the glass." This scene either remained unchanged (experiment 1) or it was completely removed before the sentence was spoken (experiment 2). Eye movements towards the table, or towards the location where the table had been, after hearing "pour" revealed an influence of the mental representation of the glass (according to the sentence it

If one's own current and past mental representations of an object's locations in a scene influence eye movements, they might also be sensitive to the processing of another's mental represen‐ tation. Adapting the visual world paradigm Ferguson and Breheny [27] reported evidence that eye movements indeed provide insight into the real-time processing of others' mental states. In an interactive video task, a participant and a confederate watched movie clips of an object that was put into one of two boxes and subsequently was pulled out of it again. After that the object was either put back into the same place or transferred to the other box. In half oft he trials the confederate did not witness whether there was a transfer or not. Thus, unlike the participant, the confederate was unsure about the final location of the object. At the end of the trial the confederate verbally described the situation as in the following scheme: "The [object] is in box [A/B]". The participants' fixations on the boxes were linked to the onsets of critical words in this verbal description. This analysis revealed a tendency to fixate the box in which the object actually ended up. Only when the confederate did not witness the object transfer, this gaze pattern changed towards an increased probability to anticipatorily fixate the alternative box, which was empty, but the confederate might have assumed that it could have been in there. This suggests that participants took into account what the other had or had not

First, this finding demonstrates that neurotypical adults are rapidly and spontaneously sensitive to other's mental states during communication. Second, this study shows that eye movements are a sensitive indicator of spontaneous and "online" ToM reasoning without

reasoning?

seen.

indicate ToM reasoning.

116 Autism Spectrum Disorder - Recent Advances

should now be on the table) on fixation patterns.

**Anticipatory eye movements.** The analysis of predictive saccades and fixations is an appealing way to address ToM reasoning. If the location where someone will fruitlessly search for an item (because of a false belief about the objects' location) is anticipated by predictive saccades and fixations, these eye movements are indicative of cognitive processes that account for the other's false belief (Schneider, Bayliss, Becker & Dux, 2012; Schneider, Lam, Bayliss & Dux, 2012; Senju, Southgate, White & Frith, 2009; Southgate, Senju & Csibra, 2007).

**Location of first fixation.** The direction of the first saccade on a scene can reveal what item is prioritized (Fletcher-Watson, Findlay, Leekam & Benson, 2008). A tendency to direct the first saccade towards the location where subjects believe an object is, rather than towards the location where the story character falsely believes it is located, may reflect an interference from one's own perspective in a false belief task (Rubio-Férnandez & Glucksberg, 2012).

**Fixation latency.** How long does it take after trial onset until a certain part of a scene is fixated? The latency until the fixation of a false belief-congruent location is informative about the characteristics of false belief attribution (Rubio-Férnandez & Glucksberg, 2012).

**Number of fixations and fixation duration.** Analyzing how often and for how long an item is fixated when viewing a scene provides information on the importance this item had in processing the scene and also on the influence of anothers' belief about that item (Keysar, Lin & Barr, 2003). Klein, Zwickel, Prinz and Frith (2009) employed fixation durations on items that elicited mental state attribution as an indicator of processing depth and interpreted it in terms of a high cognitive load, required when we ascribe mental states.

**Probability of fixating an object as a function of time.** Ferguson and Breheny (2012) showed that when another person might falsely assume an object could be in a certain location, the probability of fixating this location rose when the person started to report his or her assumption about the object's location. This procedure can reveal sensitivity to other's mental states with a crucial advantage: it serves as online measure of ToM reasoning in a natural social interaction without overtly asking for other's mental states (cf., Tanenhaus & Spivey-Knowlton, 1996).

**Pupillary dilation.** It may also be worthwhile to consider pupillary dilation. Changes in the diameter of the pupil can be linked to attentional shifts and changes in mental states (Laeng, Sirois & Gredebäck, 2012). This might not only be useful to detect if subjects react to another's mental state, but also to see which information at what point in time has led to such a response.

**Box 1.** Extractable eye movement measures in Theory of Mind (ToM) research

When interpreting eye movements in terms of underlying cognitive functions, a few meth‐ odological limitations have to be considered. When an item is fixated during a task, it may be because crucial information of that item is processed, but this must not inevitably be the case. It might also be that during the recorded fixation no information at all or different information is processed, for example in the periphery of the visual field. Aslin [28] pointed to a limitation of global looking time measures that also affects the investigation of the microstructure of eye movements via eye tracking: looking times consist of active information processing as well as blank stares. It cannot be premised that for example in free visual exploration of a scene each recorded fixation reflects active information processing of the fixated item. Furthermore it is possible that during a fixation, not the focused item is regarded, but rather different informa‐ tion is processed. Relevant information about objects can also be obtained in periphery [29]. Additionally, if a fixation reflects cognitive processing of the fixated information, conclusions to a specific cognitive process have to be drawn carefully. Depending on the employed paradigm, observed fixation patterns may reflect the detection, identification, discrimination, categorization or integration of visual stimuli. These factors have to be considered carefully when designing eye tracking paradigms to test ToM reasoning.

In sum, the rapidly increasing number of eye tracking studies on ToM reasoning suggests that the analysis of eye movements is a sensitive measure to address implicit ToM reasoning (cf., [30]). Furthermore, eye tracking appears to be especially well suited to test participants with ASD. First, it allows for inferences on social cognitive processes independent of the verbal abilities of the participants. Second, video presentation takes advantage of a strong preference of individuals with ASD for electronic screen media [31]. Third, unlike in classical false belief tasks (e.g. [32]), eye tracking versions of this task do not entail actual social interactions during stimulus presentation and assessment of measures of interest. In this way social cognition can be studied without possible aversively experienced interactions with the experimenter (cf., [33]). This promises to reduce the burden for participants with ASD to engage in the task and to enable tapping social cognitive process, otherwise masked by a disadvantageous test setting.

A recent study by Chevallier et al. [34] provides empirical support for this idea. In this study children with and without ASD completed a ToM task in a social (instructions by an experi‐ menter) and a nonsocial setting (computer-based instructions). Intriguingly, the ToM per‐ formance gap between children with ASD and neurotypical children, consistent with previous literature, was only found in the social setting. Accordingly, recording eye movements while presenting stimuli on a computer screen seems to provide comparable test conditions for participants with and without ASD. To be clear, research on social cognition in ASD should entail the study of real reciprocal social interactions (see [35]). However, one must be aware that such studies might impose too much demand on social interaction and obtained results might lead to an underestimation of social cognitive competencies of individuals with ASD.

#### **2.2. Implicit ToM reasoning and compensatory learning in ASD**

To date, the implicit ToM deficit, assessed with an implicit version of the Sally-Anne task, has been documented in adults [19] and eight-year-old children with ASD [36]. Recently, Gliga et al. [37] expanded these findings by showing that this implicit ToM deficit can not only be found in participants with an ASD diagnosis, but also in three-year-old children with an older sibling with ASD. Those children being at risk of developing a disorder from the autism spectrum, differed from a control group in their anticipation of a false-belief congruent action. Morever, Gliga et al.'s results tentatively suggest a gradient in spontaneous sensitivity to others' mental states in the autism spectrum. Within the at-risk group, only children who received an ASD diagnosis themselves later on significantly differed in their anticipatory looking from the control group. Neither at-risk children who developed typically, nor at-risk children who showed subclinical abnormalities later on, differed in their gaze behaviors from the control group. This study suggests that an implicit ToM deficit may not merely originate from isolated intra-individual factors, but may be genetically and/or environmentally determined. Further research is needed to characterize the implicit ToM deficit in the broader autism spectrum.

recorded fixation reflects active information processing of the fixated item. Furthermore it is possible that during a fixation, not the focused item is regarded, but rather different informa‐ tion is processed. Relevant information about objects can also be obtained in periphery [29]. Additionally, if a fixation reflects cognitive processing of the fixated information, conclusions to a specific cognitive process have to be drawn carefully. Depending on the employed paradigm, observed fixation patterns may reflect the detection, identification, discrimination, categorization or integration of visual stimuli. These factors have to be considered carefully

In sum, the rapidly increasing number of eye tracking studies on ToM reasoning suggests that the analysis of eye movements is a sensitive measure to address implicit ToM reasoning (cf., [30]). Furthermore, eye tracking appears to be especially well suited to test participants with ASD. First, it allows for inferences on social cognitive processes independent of the verbal abilities of the participants. Second, video presentation takes advantage of a strong preference of individuals with ASD for electronic screen media [31]. Third, unlike in classical false belief tasks (e.g. [32]), eye tracking versions of this task do not entail actual social interactions during stimulus presentation and assessment of measures of interest. In this way social cognition can be studied without possible aversively experienced interactions with the experimenter (cf., [33]). This promises to reduce the burden for participants with ASD to engage in the task and to enable tapping social cognitive process, otherwise masked by a disadvantageous test setting.

A recent study by Chevallier et al. [34] provides empirical support for this idea. In this study children with and without ASD completed a ToM task in a social (instructions by an experi‐ menter) and a nonsocial setting (computer-based instructions). Intriguingly, the ToM per‐ formance gap between children with ASD and neurotypical children, consistent with previous literature, was only found in the social setting. Accordingly, recording eye movements while presenting stimuli on a computer screen seems to provide comparable test conditions for participants with and without ASD. To be clear, research on social cognition in ASD should entail the study of real reciprocal social interactions (see [35]). However, one must be aware that such studies might impose too much demand on social interaction and obtained results might lead to an underestimation of social cognitive competencies of individuals with ASD.

To date, the implicit ToM deficit, assessed with an implicit version of the Sally-Anne task, has been documented in adults [19] and eight-year-old children with ASD [36]. Recently, Gliga et al. [37] expanded these findings by showing that this implicit ToM deficit can not only be found in participants with an ASD diagnosis, but also in three-year-old children with an older sibling with ASD. Those children being at risk of developing a disorder from the autism spectrum, differed from a control group in their anticipation of a false-belief congruent action. Morever, Gliga et al.'s results tentatively suggest a gradient in spontaneous sensitivity to others' mental states in the autism spectrum. Within the at-risk group, only children who received an ASD diagnosis themselves later on significantly differed in their anticipatory looking from the control group. Neither at-risk children who developed typically, nor at-risk children who showed subclinical abnormalities later on, differed in their gaze behaviors from the control

when designing eye tracking paradigms to test ToM reasoning.

118 Autism Spectrum Disorder - Recent Advances

**2.2. Implicit ToM reasoning and compensatory learning in ASD**

Both ToM reasoning systems, the explicit and the implicit one, appear to be affected in ASD. However, there seems to be a dissociation with respect to the possibility to tackle an explicit and an implicit ToM deficit by compensatory strategies (see [2,21]): On the one hand, individ‐ uals with ASD are able to alleviate an explicit ToM deficit through compensatory learning. Experience with social situations may have led to the acquisition of non-mentalistic routes to deal with mental states of others. Evidence that high functioning individuals with ASD pass explicit ToM tasks supports this notion [20].

On the other hand, based on the finding that those participants with ASD who passed explicit ToM tasks, showed no spontaneous sensitivity to a character's false belief in an implicit ToM task [19], it was argued that this implicit ToM deficit is pervasive and cannot be modulated by compensatory learning. Moreover, if implicit ToM reasoning runs automatically, without topdown control [38], it should not be susceptible by alternative, non-mentalistic, strategies.

Callenmark, Kjellin, Rönnqist and Bölte (2013) [39] report a similar dissociation between explicit and implicit social cognitive processes. In an explicit version of a social cognition task (multiple-choice rating of other people's thoughts about violations of social norms) adolescents with ASD did not differ in their performance from neurotypical controls. However, in a more implicit version of this task (free interview instead of multiple-choice format) the ASD group performed more poorly as compared to the neurotypical control group. In a similar vein to Senju et al [19], the authors concluded that in explicit but not in implicit tasks, compensatory strategies which were acquired through learning and experience with social situations, can be employed.

A limitation of the above described implicit false belief tasks is that they only employed one critical test trial to assess gaze behavior that indicates a lack of spontaneous sensitivity to mental states in ASD. However, claiming that individuals with ASD have a persisting implicit ToM deficit requires testing whether atypical gaze behavior is sustained over time. Such an implicit ToM deficit, impenetrable by learning from experience, should be observable in the consecutive presentation of multiple test trials and should not be alleviated by the repetition of those trials.

Using a methodologically refined version of the implicit false belief task, Schneider, Slaughter, Bayliss and Dux [40] tested this hypothesis in adults with ASD. First, they replicated the previously observed group difference between participants with and without ASD in falsebelief congruent anticipatory looking. Second, for both groups gaze behavior remained stable over the repetition of test trials: Whereas the neurotypical control group showed sustained false belief-congruent anticipatory looking, individuals with ASD revealed a persisting lack of this false belief tracking. Additionally, just like in Senju et al.'s [19] study, the same partic‐ ipants passed explicit ToM tasks. This empirically underpins the proposal that individuals with ASD can employ explicitly learned strategies to face an explicit ToM deficit and that those strategies are useless to tackle an implicit ToM deficit. Furthermore, these findings critically extend previous suggestions by adding the notion that experience with the implicit false belief task (through repeating the test trials) does not trigger spontaneous compensatory learning.

In contrast to the finding by Schneider et al. [41], Schuwerk, Vuori and Sodian [42] reported apparently contradictory results. They also adapted Senju et al.'s [19] paradigm to test learning effects on false belief-congruent anticipatory looking in adults with ASD. In order to assess the impact of experience on gaze behavior, the critical false belief test trial was repeated once. Eye movement patterns in the first presentation of the false belief test trial revealed the welldocumented group difference between the participants with ASD and the neurotypical controls. However, in the subsequent repetition of the test trial, anticipatory looking of the ASD group no longer differed from the neurotypical control group.

Why did Schneider et al. find no effect of experience in a total of ten subsequently presented false belief trials whereas in Schuwerk et al.'s study the single repetition of the false belief trial was sufficient to make the group difference disappear? One task property, which was changed by Schuwerk et al., but not by Schneider et al., can serve as explanation of those discrepant findings. In contrast to previous versions of this implicit false belief task, Schuwerk et al. presented the belief-corresponding action (the agent is searching for the object in the now empty box), and its outcome (the actor does not find the car). Therefore it is possible that presenting a perception-action contingency (agent does not witness the transfer – agent searches for the object in the wrong box) provided a basis for individuals with ASD to learn about the association between the agent's gaze direction and the subsequent action. Notably, this learning from experience can result in the observed alternation of gaze behavior without the need to actually consider the actor's mental state. Thus, this finding suggests that individ‐ uals with ASD are sensitive to behavioral cues to learn about perception-action contingencies. Furthermore, this knowledge can be employed as compensatory strategy to rapidly adapt action predictions in an implicit ToM task.

#### **2.3. Summary**

In sum, evidence is accumulating that implicit ToM reasoning is impaired in individuals with ASD and also their younger siblings. Moreover, compensatory non-mentalistic strategies, which are useful in explicit ToM tasks, fail to alleviate the deficit to spontaneously appreciate another's mental state. However, recent findings show that the strict distinction that explicit, but not implicit ToM reasoning can be addressed by compensatory learning, may not be tenable. It rather seems that also the implicit ToM deficit can be modulated by compensatory strategies: if individuals with ASD are provided perception-action contingencies, they may also be able to rapidly use this information to anticipate another's false belief-based action. We propose that the implicit ToM deficit in ASD is not as persistent and impenetrable as it seems. Future research has to evaluate possibilities to tackle the lack of spontaneous belief apprecia‐ tion with learning from experience. More evidence for compensatory learning in implicit social cognition would support the previously tentatively stated idea that compensatory strategies can be taught to face impaired implicit social cognitive processes in ASD [43].

To conclude, the analysis of eye movements has substantially advanced our understanding of ToM reasoning in ASD. The advantage of eye tracking to tap into more implicit social cognitive processing makes this method an integral part of future research on two-systems accounts of functional and dysfunctional ToM.
