There are many ways in which eye gaze could be measured:
> Frequency of eye gaze
> Mutual gaze (Rubin, 1970)
> Blink rate
> Pupil dilation (Hess, 1972)
> Eye expression
Eye Tracking technology becomes increasingly wide-spread, making it possible to see with incredible precision, for how long exactly and in which sequence a person looks at every particular place of a picture/video etc. This technology opened many new opportunities - including studying children with autism and other developmental abnormalities, and how their gazing patterns differ from typically developing children. I will discuss some of the recent research in this field further down in this post. I will also talk about gaze aversion, and its implications for primary education.
Eye Gaze: functions
1. Send social signals
As to this function, there are certain norms and rules; if broken, eye gaze perceiver is likely to be confused or offended. For example, Kleck and Nuessle (1968) found that those who directed only 15% of their eye gaze to a conversation partner (on film) were perceived by others as 'cold' and 'insensitive', while those who directed 80% - as friendly and sincere. However it is not only about the total amount of gazing. There are also social norms of how long a single glance should last; appropriate amount of gaze also depends on distance between the two people, and also - on their gender. Women tend to make less eye contact with men than with other women.
Thus, we see already that eye gaze is an important tool of social communication and can influence others' impression of ourselves.
2. Receive information
3. Controls synchronisation of speech
There is much evidence that humans synchronise their speech during the social interaction. They tend to mimic the intonations, sentence structures etc.of each other. People use eye gaze to pick up on these aspects of interaction and adjust accordingly.
As to animals, they use eye gaze to send signals, for example threat signal (Exline & Yellin, 1969), or to collect information from others - however, they do not use eye gaze in communicative way as people do.
Eye Gaze in infants
> It has been shown that infants have an innate interest in eye-like stimuli (e.g. Fantz, 1961) using the method of preferential looking.
> By 2 1/2 weeks infants develop mutual gaze; it was shown that delay in developing mutual gaze could be a signal of a delayed cognitive development. In a way, it is a vicious circle: when mutual gaze develops, it increases arousal of both parents and infants, encourages more interaction - and, therefore, more learning and bonding. In cases when mutual gaze is delayed, there is less interaction with the caregivers, which encourages further developmental delay.
> Infants as young as 3-6 months old are able to track others' gaze - however, only when the whole head is moving; they can not yet track eye movements alone (Scaife & Bruner 1975). Also, initially they track eye gaze without understanding its the significance. By 14-18 months they respond to eye cues alone. It is also during this time when triadic attention develops: that is, if another person is looking at someone/something else, infant is able to follow the gaze and switch their own attention to this person/object.
> Tracking eye gaze is an important stepping stone in development. It allows for the development of joint visual attention and social referencing, which encourage emotional development, language acquisition and cognitive development - including Theory of Mind (ability to understand others' mental state
> Theory of Mind develops by four years old. It is then when children develop mentalistic understanding: understanding others' thoughts from their eye gaze. Therefore, we can see that eye gaze may play its role in ToM development, but is not the only factor at work as it develops much earlier than ToM.
Eye Gaze and Autism
> Show little joint visual attention
> Don't use - or use much less - declarative gaze (Charman 2000).
> Don't focus on eyes during interaction, look more at mouth region (e.g. Dalton et al. 2005). It is suggested that it is a coping, compensating mechanism: they rely on mouth to understand the situation, being unable to extract information from eyes.
> Don't use eye gaze for feedback or turn-taking; also, don't maintain eye gaze while listening (Attwood, 1998).
> Don't use eye gaze to show intention, desires, thoughts (Baron-Cohen, 1995).
Nowadays, eye tracking technology allows to see how eye gaze in autistic children differs from normally developing children. It was repeatedly found that autistic children tend to fixate their gaze at objects and persons' mouth areas, while normally developing children - at faces, particularly eye areas. At the following picture, white crosses show where normally developing children fixated their gaze; black crosses are fixations of autistic children.
Developmental changes in Eye Gaze
1. Decreasing dependance on visual signals. It is possible that, as language and other means of communication develop with age, children's need for visual signals as a source of information about the world decreases, resulting in less frequent eye gaze.
2. Increasing awareness of social rules of behaviour. With age, children learn social norms which include the appropriate length of gazing at other people. Scheman & Lockard (1979) showed that younger children were much less likely to avert their gaze from a staring adult - however they learn to do so by about 5 years old. Abramovitch & Daly (1978) argued that children did not use gaze to judge liking and friendship till about 6 years old. Till then, they stare at people more frequently, because they do not put any social meaning into their gaze. After they learn that prolonged gazing is a sign of affection, they only have a long eye contact with close people, not with strangers.
In his study (you can find the paper here), Doherty-Sneddon et al. gave children of 5 and 8 years old several maths problems. It was found that all the children averted their gaze while thinking; however, both quantitative and qualitative differences of gaze aversion were shown between the age groups. 8 years olds averted their gaze much more. Also, they used sustained eye movements to the right, while 5 years olds predominantly used quick, multi-directional 'flicking' movements. They also found that gaze aversion increased in proportion to difficulty of a question/problem.
These findings have significant implications for teaching. Gaze aversion is typically understood by teachers as a sign that a child had 'switched off', stopped listening or gave up thinking of an answer - while in fact, it is likely to signify active thinking on a problem.