Chapter 6: General Discussion and Conclusions

6.2 Summary of findings

The main findings from each chapter can be seen in Table 6.1. An important finding, replicated across chapters, was that first fixations to the eye region were difficult to inhibit even when participants were explicitly told to look to the mouth to help them to successfully complete the task. This bias is also supported by the time to

first fixate data in Chapters 4 and 5, as across conditions participants first fixate on the eye ROI more quickly than the mouth ROI. Crucially, this eye bias was also found in participants with an ASD, as demonstrated by the lack of group differences in eye tracking data in Chapter 5. In summary, NT adults and autistic and TD children aged 8- 11-years-old all demonstrate a bias to first look to the eyes during face viewing that is difficult to inhibit.

The development of the control task using house stimuli in Chapters 4 and 5 helped to demonstrate that the eye bias is face specific and not a generic bias to look towards the top of the image. Across the two chapters no substantial differences were found between the accuracy, RT and looking patterns of the windows and the door. The exception to this was that in in both Chapters 4 and 5 the RTs were shorter for the door change than the window change conditions and there was some evidence of looking to the door more quickly than the windows across both chapters. Critically, there was no difficulty inhibiting the bias to look to the windows, i.e. the feature in the upper part of the image, nor was there any difficulty in following the prompt to look to the doors. Further, although there were some minor differences between door and window looking there were no substantive differences that would suggest issues with understanding the task, which was particularly important to establish in the ASD group.

Finally, a ‘reversed order’ manipulation was introduced in Chapter 4 to eliminate the possibility that the improved performance in the prompted condition, which was performed second to prevent biased looking patterns in the unprompted condition was the result of a practice effect. In the reversed order manipulation, the prompted condition was completed first for 15 children and no significant differences in the pattern of results were observed with the children completing in the standard order. These data help to support the evidence that the effects of prompting are specific experimental effects.

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Table 6.1: Summary of the key findings in each chapter

Participants Key methodological details Key findings

Chapter 2 94 ASD adolescents and 54 non-ASD adolescents  Behavioural measures of accuracy and RT.  3500ms presentation time Accuracy:

 In the unprompted condition the ASD group were less accurate than the non-ASD group. In the prompted condition there was no overall difference.

 In the unprompted condition both groups showed greater accuracy for the eyes than the mouth. There were no differences in the prompted condition.

Reaction time:

 Overall the ASD group had shorter RTs than the non-ASD group.

 Both groups demonstrated shorter RTs for the eye change images than the mouth change images in the unprompted condition, but shorter RTs for the mouth change images than the eye change images in the prompted condition.

Chapter 3 41 NT adults  Behavioural measures of accuracy and RT.  Eye tracking measures of

dwell time and first fixation location.

 700ms presentation time.

Accuracy:

 More accurate for eye change images than mouth change images in the unprompted condition. No significant differences in the prompted condition.

Reaction time:

 Shorter RTs when the eye was the changed region compared to the mouth in the unprompted condition. No significant difference in the prompted condition. Unprompted eye tracking data:

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 Dwell time was longer for the eyes than the mouth Prompted eye tracking data:

 When prompted to look to eyes, first looks were more often to the eyes than the mouth. When prompted to look to the mouth, there were no difference in first look locations.  When prompted to look to the eyes overall dwell time was longer to the eyes. When

prompted to look to the mouth overall dwell time was longer to the mouth. Comparison of unprompted and eye prompt data:

 No differences found in any eye tracking data across the two conditions. Chapter 4 64 TD 8-11-year-olds

(50 in the main task and 14 as a reversed order group)

 Behavioural measures of accuracy and RT.  Eye tracking measures of

dwell time, first fixation location and time to first fixate.

 2000ms presentation time  Reversed order group to

control for order effects  Control task (houses)

Accuracy:

 More accurate for eye change images than mouth change images Reaction time:

 No difference in RTs for the eye and mouth change images Unprompted eye tracking data:

 First looks more often to the eyes than the mouth  Looked to the eyes more quickly than to the mouth  Dwell time was longer for the eyes than for the mouth Prompted eye tracking data:

 When prompted to look to eyes, first looks were more often to the eyes than the mouth. When prompted to look to the mouth, there were no difference in first look locations.  When prompted to look to both the eyes and the mouth, participants were faster to look to

the eyes than the mouth.

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prompted to look to the mouth overall dwell time was longer to the mouth. Comparison of unprompted and eye prompt data:

 No significant differences in mouth dwell times and mouth first looks across the two conditions.

 Significantly more eye looking and first looks to the eye in the eye prompt condition than the unprompted condition.

Chapter 5 14 ASD children and 14 TD matched control group

 Behavioural measures of accuracy and RT.  Eye tracking measures of

dwell time, first fixation location and time to first fixate.

 2000ms presentation time  Control task (houses)

Accuracy:

 More accurate for eye change images than mouth change images (near significant) Reaction time:

 ASD group: Shorter RT for the eye compared to the mouth change images in the unprompted condition.

 ASD group: Shorter RT for the mouth compared to the eye change images in the prompted condition.

 TD group: No overall differences in RT between eye and mouth change images. Unprompted eye tracking data:

 Dwell time was longer for the eyes than for the mouth. No group differences

 More first looks to the eyes than to the mouth in both groups. ASD group had less first fixations to either ROI compared to the TD group.

 Non-significant pattern of looking to the eyes more quickly than mouth Prompted eye tracking data:

 When prompted to look to the eyes, overall dwell time was longer to the eyes. When prompted to look to the mouth overall dwell time was longer to the mouth. No group

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 differences

 When prompted to look to eyes first looks were more often to the eyes than the mouth. When prompted to look to the mouth no difference in first look locations. No group differences.

In document Measuring the bias to look to the eyes in individuals with and without autism spectrum disorder (Page 130-136)