Chapter 1: Introduction
1.4 The use of alternative eye tracking measures
1.4.4 Gaze following in NT and ASD participants
An alternative way to consider whether people look to the eye region and how this information is spontaneously attended to is through gaze following paradigms. These experiments typically present a face or whole person on the screen that moves their gaze in a certain direction or towards a specific object. Participant response to this gaze can be measured either by RT to respond to a target object or through the use of eye tracking. This ability to follow gaze direction is seen from a young age in TD individuals. For example, it has been found that children as young as twelve months old are able to respond to objects cued by an adult’s gaze (Tatler, Hayhoe, Land, & Ballard, 2011). This effect is also consistently seen in adults, for example in one study participants would look to the actors eyes and then to the object that the actor was looking at to understand the scene that was presented to them (Castelhano, Wieth, & Henderson, 2007). In addition, in a real life interaction, adults were able to use the gaze cues given in conversation to fixate on the correct target piece when completing a construction task (Macdonald & Tatler, 2013).
Numerous studies have used different types of gaze cueing paradigms to compare performance of ASD and NT individuals to understand how those with ASD process the eye region. Although using very different methodology, these studies have all found no group differences between the ASD group and the NT control groups. Using a novel paradigm, Freeth, Ropar, Chapman, and Mitchell (2010) presented
stimuli with either a person looking out towards the camera or gazing towards an object in the scene and asked the adolescent participants to draw a frame around the image so that the image made sense to them. When gaze was towards the camera both groups framed the person in the centre of the image, suggesting the person was the key element of the scene. However, interestingly when the person was gazing at an object both groups seemed to spontaneously attend to the eye gaze and include the gazed object as a central part of their framed image. In addition, a second experiment was conducted whereby the participants had to detect which item was missing on the second presentation of the image. Both the ASD and TD participants detected this change quicker when it was the object being gazed to by the actor in the scene. In a further study, Freeth, Ropar, Mitchell, Chapman, and Loher (2011) found no difference in the amount of gaze direction mentioned by the two groups of
adolescents when they were asked to describe the scene in front of them. Comparable results have also been seen in an eye tracking study which found that there was no difference in gaze following between a group of ASD adolescents and a TD control group, suggesting they both spontaneously followed gaze to the same extent (Freeth, Chapman, et al., 2010).
Research involving the use of visual illusions within magic tricks can be
important for understanding the role of gaze following, as magic tricks often use subtle social cues to misdirect attention. In one study the illusory ball trick was used to establish whether NT adult participants would automatically look to the
experimenter’s eyes to infer information about the trick that was being performed (Kuhn & Land, 2006). In this trick the experimenter throws a ball up to catch it whilst following the ball with his eye gaze twice and then on the third trial pretends to throw the ball up whilst concealing it in his hands, either following the imaginary ball with the eyes (pro-illusion condition) or looking down to his hands (anti-illusion condition). More participants in the pro-illusion condition reported seeing the ball than in the anti-illusion condition and often stated they had seen the ball disappear off the top of the screen and the illusion was created by someone catching it above the screen. In addition, most of the participants claimed they spent the whole time looking at the ball, despite looking to the eyes most of the time. The same paradigm was later used to compare looking patterns and susceptibility to the illusion in young adults with ASD and a NT control group (Kuhn et al., 2010). In this study, it was found that there was no
difference in the amount of time that the ASD and NT groups spent looking to the eyes and that the ASD group were even more susceptible to the illusion, than the NT group. This again suggests that both the ASD and NT participants were spontaneously looking to the eyes and extracting information from the gaze direction, without being
instructed to do so.
Overall, the gaze following data presents a perhaps surprising picture
considering the diagnostic criteria and common understanding that autistic individuals have atypical levels of eye contact. The previous studies suggest that both NT and ASD groups spontaneously attend to the eye region and then spontaneously follow the gaze from the eyes to look to other objects. Again, these findings suggest that it is important to further investigate how instinctively or automatically autistic individuals attend to the eye region in a range of different paradigms and using a range of different eye tracking measures.