An occasionally irregular blog about orthodontics

Perception of facial appearance: What do people look at when they look at you? :

By on April 20, 2015 in Clinical Research, Recent posts with 1 Comment
Perception of facial appearance: What do people look at when they look at you? :

Perception of facial appearance, smiles and eye tracking

After all the excitement of last weeks blog which was read by 5,000 people in three days, this blog brings us back to the real world of modern orthodontics.  I am going to discuss a paper that appeared in the latest edition of the AJO-DDO and this is on the perception of facial appearance and the way that our eyes concentrate on different facial features.

Unknown-2Contribution of malocclusion and female facial attractiveness to smile aesthetics evaluated by eye tracking.

Richards M et al

AJO-DDO 2015:147: 472.  Doi: http://dx.doi.org/10.1016/j.ajodo.2014.12.016

What did they ask? 

They started with a good description of the  the literature on the effects of facial and dental attractiveness.  Most of the evidence they cited was developed from  a series of studies that evaluated the perception of groups of raters who viewed still life pictures of faces with different arrangements of teeth.  They summarised by concluding that the effect of dental appearance on perceived attractiveness is influenced by the gender and overall attractiveness of a person’s face.  However, they drew attention to the fact that in the previous work the groups of raters were directed towards the mouth and teeth by the investigators; and this may have resulted in bias in these studies.  They proposed that another approach to this type of study is to determine what viewers actually look at when presented with different facial images. They suggested that this could be achieved by using eye tracking technology.  Their study question was

“What do people look at in facial images when the dental and facial appearances change from near ideal to average or normal to recognisably poor”?

 What did they do?

This was rather a complicated study as they took several steps to minimise any bias etc. They did the following:

  1. They obtained facial images of 207 female students by approaching people on the University campus.
  2. 36 young adults, with no professional dental expertise, rated 199 of the smiling images for attractiveness.  These images were then ranked for attractiveness.
  3. They then collected images of anterior teeth from the records of the orthodontic department. These were then scored with the Aesthetic Component of the Index of Orthodontic Treatment Need (IOTN).
  4. The three levels of facial images were then paired with the three levels of dental images. This resulted in a sample of composite images of varying dental and facial attractiveness.
  5. Then they recruited a further 78 other people from the Psychology department at the University. These people  then viewed the photographs using the eye tracking software etc. This recorded the areas of the photographs that their eyes rested upon.

The data were analysed with appropriate statistics.  I am not going to describe these here but they needed to take into account several interactions, so this was complicated.

What did they find?

In the results, they spent considerable time outlining important factor, such as, reliability etc. While this was necessary for the paper, I am not going to go into detail here.  The main important finding were:

  • The eyes were the facial feature that were viewed the most, followed by the mouth and the nose.
  • As the dental attractiveness decreased, visual detection decreased for the eyes and increased on the mouth.
  • The more attractive the facial appearance was, the lower the level of dental unattractiveness was needed to draw attention away from the eyes.

What did I think?

This was an interesting and rather complex study.  I thought that they used a good methodology and their analyais was appropriate. I did find it difficult to interpret the results, but this is a complex area.

My feeling was that this s study showed that the mouth is an important salient feature when a face is viewed.  I found it interesting that  if a person has an attractive face then the effect of unattractive teeth was more marked.  I am not sure how this finding translates to the real world of clinical practice? It could be suggested that if orthodontic treatment is restricted or prioritised then it should be provided to people who are essentially already attractive. But this is counterintuitive and the authors do not really address this in the discussion.

Nevertheless, they did show that the appearance of the mouth and the teeth does influence the way that faces are viewed and this is an important finding.

As with all studies of this nature, it is very easy to be critical and it is clear that there are some issues with the validity of the group of raters. This is because they were selected from a group of young people who were attending a University. As a result, we must assume that they are different from the general population.

The other important factor that we need to consider is that studies that evaluation perceptions using “still life” photographs may only approximate to the “real world” situation where our perceptions are influnced by interaction with a person. I am sure that we have all met someone who is very attractive but when we interact with them we feel that we do not want to be friends with them!

However, I felt that this was a useful study that did add to knowledge on the way that we look at people’s faces.  This certainly acts as a pointer to further work as more researcher concentrate on the social aspects of orthodontic treatment and malocclusion.

ResearchBlogging.orgRichards, M., Fields, H., Beck, F., Firestone, A., Walther, D., Rosenstiel, S., & Sacksteder, J. (2015). Contribution of malocclusion and female facial attractiveness to smile esthetics evaluated by eye tracking American Journal of Orthodontics and Dentofacial Orthopedics, 147 (4), 472-482 DOI: 10.1016/j.ajodo.2014.12.016
 

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  1. I think the inference here is that attractive people are expected to have better looking teeth and this make sense. If you see a beautiful woman (or man) before they smile and then show their teeth, your expectation is that they will also have beautiful straight teeth. Otherwise you will likely be surprised and disappointed if they smile and have crooked or missing teeth in front. Conversely, if you see an unkempt, tattered looking person and they expose their unsightly mouth, you are more likely to expect that, so no surprise here.

    The message to us in dentistry is that a beautiful smile elevates the overall expectation for the person who shows it, and that we have the power to change lives by providing a beautiful smile for our patients. How lucky we are!

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