Particularities of Visual Scanning in Static vs Dynamic Situations for Asperger’s Subjects: New Advance in ASDs

Research Article

Austin J Autism & Relat Disabil. 2016; 2(4): 1028.

Particularities of Visual Scanning in Static vs Dynamic Situations for Asperger’s Subjects: New Advance in ASDs

Giuliani F¹* and Armi ND1,2

1Department of Psychiatry at the University Hospital, CHUV, Switzerland

2Institute of Psychology, University of Lausanne, Switzerland

*Corresponding author:Fabienne Giuliani, Community Psychiatry Unit, Department of Psychiatry at the University Hospital, CHUV, Cery site, 1008 Prilly, Switzerland

Received: June 29, 2016; Accepted: August 01, 2016; Published: August 03, 2016


Context: Several previous studies have already used eye-tracking technology to demonstrate the particularities of visual scanning in ASD individuals. In this study, in order to compare two situations, a group of Asperger’s individuals and a control group were subject to experimental conditions: a static and a dynamic situation. The goal was to first compare the visual scanning between the two groups and then to compare the visual scanning of the Asperger’s group within each condition. We hypothesized that the visual scanning of the Asperger’s group would be different in the dynamic situation, compared to the norm.

Results: We found a significant difference in visual scanning between the Asperger’s group and the control group in both experimental conditions. These results demonstrate the particularities of visual scanning in individuals with Asperger’s syndrome.

Conclusion: According to our results, individuals diagnosed with an ASD have difficulties when confronted with dynamic stimuli. We were able to demonstrate that Asperger’s individuals use their peripheral vision regardless the kind of stimuli. We were also able to conclude that eye-tracking is an effective aid in screening for ASDs.

Keywords: Asperger’s Syndrome; Eye-tracking; Static stimuli vs dynamic stimuli; Screening; Quantitative data vs qualitative data


Asperger’s Syndrome is, according to the current DSM-V (2013) [1], a neuro-developmental disorder classed among the larger denomination of Autism Spectrum Disorders (ASD). ASDs are disorders affecting approximately 1% of the population [2] and affect boys four times more than girls [2,3]. ASDs are characterized by diverse and varied symptoms with respect to communication, behavior, and relationship-based difficulties [4].

In the DSM-IV (2000) [5], Asperger’s Syndrome is its own diagnostic category, and does not include mental impairment. For a more detailed and socio-demographic profile of individuals living with Asperger’s Syndrome, see Giuliani and El Korh (2016) [3]. Note that in this study we reference Asperger’s Syndrome because the participants all received their diagnosis according to the criteria of the DSM-IV, in which Asperger’s is a separate diagnostic and is not included within other autism spectrum disorders. However, the characteristics of Asperger’s syndrome are those of ASD.

Visual exploration is directed at salient elements in the environment [6]. Salience is determined by notice ability (i.e., any form of sensory intensity, e.g. size, brightness, suddenness or an unpredictable movement) or novelty (spatial reorganization of familiar elements) [7].

Visual exploration helps to acquire and process information concerning the environment, particularly spatial information, during a spontaneous learning process [8]. Familiarity develops through a dynamic process, i.e., the lowering of response to a stimulus when repeatedly subjected to it. Habit has traditionally been considered as the most simple and most primitive form of learning [9].

Concerning the duration of fixation, Saint-Aubin, Tremblay and Jalbert (2007) [10] provide evidence that the length of time that the gaze falls on an object in a static image is linked to the probability that the participant remembers the object. This is why it is important to study where the participants fix their gaze, and to consider the time spent on the fixation point. The information thus coded is spatial and temporal.

The duration of fixation varies in function of the situation. As Hooge, Vlaskamp and Over (2007) [11] have shown, if the duration of fixation is too short, the image on the retina will be swept away by the following image, even before the information has been analyzed by the visual system.

Studies which use eye-tracking in order to analyze visual scanning show that there are differences between the general population and those diagnosed with an ASD [12-14]. Eye-tracking is able to measure several parameters including the number and duration of fixation points as well as pupil diameter [15, 16]. Furthermore, it has proven to be a helpful tool for cognitive behavioral therapies when treating these disorders [15-17].

Based on the many studies using eye-tracking and the replication of results from studies conducted with this tool, we can envision the use of oculometry as an effective screening method for ASDs. Essentially, studies show an important contribution of eye-tracking during the processing of stimuli, making it possible to detect disorders [12], as well as an early screening which facilitates the undertaking of rapid treatment [18], and identifying children who are at-risk [19].

From an early age, babies are more attracted by dynamic stimuli than static ones [20], and have a preference for biological or human movements [21,22]. Tardif and Gepner (2009) [20] report that autistic children show differences at the dynamic level, and that the vision of movement proves to be lacking, while their vision of static stimuli is normal compared to children with normal development [19]. Deficits in dynamic vision explain in part the differences of individuals living with an autism spectrum disorder or Asperger’s, like communication and social interactions [23] as well as motor skills [24].

To understand these particularities in individuals with an ASD, the use of eye-tracking is an effective method to understand the visual scanning of static and dynamic stimuli [12]. This is the method that will be used in this study.

Materials and Methods


A total of 58 adults participated in the study, 24 with an Asperger’s diagnosis (41.37%) and 34 control subjects (58.62%). The sample was comprised of 27 women (46.55%) and 31 men (53.45%). The subjects of the experimental group received a diagnosis according to the criteria of the DSM-IV: (1) a qualitative impairment in social interactions, (2) restricted repetitive and stereotyped patterns of behavior, interests and activities (3) impairment leads to a marked clinically-significant impairment in social, professional and other areas, (4) still at the clinical level, no significant delay in cognitive development during childhood or development, and (5) the disorder cannot fulfill the diagnostic criteria for schizophrenia or another developmental disorder.

Participants with an Asperger’s diagnosis were treated in a department of Psychiatry of Mental Development (SPDM), belonging to the Vaud University Hospital (CHUV). The “control” group was recruited through advertising among the staff of the department, all of which had obtained a secondary level of education. Everyone signed a consent form concerning the use of their clinical data for research purposes. All data was confidential and made anonymous.

Experimental protocol and stimuli

Based on the empirical data views introduction, we came up with a hypothesis that visual scanning of Asperger’s individuals must be different compared to the norm in a dynamic situation. To confirm or refute our hypothesis, we used two types of stimuli: a static one and a dynamic one.

The static stimulus consisted of putting the person in front of a simple matching task on a computer. On the left side of the computer screen was the image to be matched, and on the right side there were four suggestions; the person had to find the matching image from among the four propositions. This task was developed and published by Hadjikhani, Joseph, Snyder, and Tager-Flusberg (2007) [25]. In this “static” situation, we measured the fixation points, their length as well as how the movement of visual scanning was organized.

For the dynamic stimulus, the individuals were asked to take a walk through our facility, following the same path and without receiving any particular instruction. Similar to the static situation, we also measured the fixation points, their length as well as how the movement of visual scanning was organized.

To evaluate the two types of stimuli, eye-tracking (ASL, for more information on the tool, see Giuliani and El Korh (2015) [15] and Giuliani, Favrod, Bonsack, & Schenk (2009) [17]) was used to record the visual scanning of the participants.

Data analysis

Data analysis was done using the Statview 5.0 software. Repeated measures ANOVA were conducted to test the differences between the two groups, between the sexes and the interaction between each group and each sex. Unpaired T-tests made it possible for us to see if there were any differences between the sexes between the types of stimuli and within each group. Also, graphs were created to visualize the fixation point averages as a function of group and sex.


Static situation - Simple matching on a computer

The results of the repeated measures ANOVA on the average of the fixation points made in the simple matching situation indicate a significant different between the groups. On average, the Asperger’s group made significantly more fixation points (μ=.606±.086) compared to the control group (μ=.421±.092 ), with ANOVA F (1,22)=34.266, p<.0001. There was no sex effect (F (1,22)=3.449, p=.0767) nor any interaction effect between the group and sex (F (1,22)=0.264, p=.6124). This significant difference shows that the Asperger’s group has a significant slowing of visual scanning.

The unpaired T-tests on the average duration of the fixation points gave us non significant results, implying that there was no difference between sex and this was for neither the Asperger’s group (t (22)=2.006, p=.0586) nor the control group (t (22)=-.693, p=.4957). This indicates that the average duration of the fixation points, within each group, is fairly the same between men and women. For a more detailed view of these results, see Figure 1.

Citation: Giuliani F and Armi ND. Particularities of Visual Scanning in Static vs Dynamic Situations for Asperger’s Subjects: New Advance in ASDs. Austin J Autism & Relat Disabil. 2016; 2(4): 1028.