Introduction
Our daily lives are filled with emotions that represent an important aspect of social life. It has been shown that facial recognition performance decreases with age especially regarding negative emotions. This result is also highlighted in elderly with Alzheimer’s disease with even lower performance than healthy older adults. It appears that face recognition can be influenced by an “own-age bias” resulting in better recognition for faces belonging to its own age category. This phenomenon has been little discussed in people with Alzheimers’s disease, the purpose of this study is to investigate the own-age bias in this population. We have tried to objectify the existence of this phenomenon and to study its impact on the performance of Alzheimer’s subjects.
Method
Twenty-seven people took part in this study including ten healthy young people (M = 21.80, SD = 2.49), ten healthy elderly people (M = 72.4, SD = 3.47) and seven elderly people with Alzheimer’s disease (M = 78.29, SD = 3.35). This study consisted of two tasks. The first one was a task of identifying emotions (joy, sadness, disgust, fear). The participants had to identify the emotions displayed either on young faces or on aged faces. They were also sometimes confronted with neutral faces (control condition) in which case they simply had to say whether the face presented was female or male. The second part of the experimentation task was a recognition task. Participants were faced with face shots and had to say whether it was a new face or a face already presented in the previous task.
Results
Regarding the identification task, young subjects perform better than healthy older participants who are more successful than participants with Alzheimer’s disease. In addition, the results highlight that young and older people identify emotions better when they are presented faces belonging to their own age group. However, Alzheimer’s subjects equivalently identify emotions whether they are presented on faces belonging to their own age group or not. For the recognition task, we note that young people perform better than healthy seniors who themselves perform better than Alzheimer’s. Concerning the neutral stimuli, the three groups of subjects recognize better neutral faces belonging to their own age group. With reference to the emotional stimuli, young people recognize both young and old people. For healthy older people and Alzheimer’s, they recognize better the faces of people in their own age group.
Discussion / Conclusion
Identification task
There is no statistically found own-age bias for Alzheimer’s subjects despite a trend in this favor. The smallness of the Alzheimer’s group (N = 7) can account for the absence of this phenomenon. For healthy young and elderly subjects, a statistically significant own-age bias phenomenon is well identified. Since, to our knowledge, the question has never been the subject of research, for the moment we have no explanatory hypothesis for these results. A hypothesis put forward by Bortolon and his contributors (2015) in the context of a neutral faces recognition task in the Alzheimer’s disease, proposed to explain the own-age biais observed by the frequency of meeting participants with people belonging to their own category of age.
Recognition task
As with the identification task, we can conclude here that there is an own-age bias in neutral face recognition for each of the three groups of participants. For healthy elderly subjects and Alzheimer’s subjects, the own-age bias phenomenon seems to extend to emotional stimuli. On the other hand, the group of young people does not present a statistically significant own-age bias in condition of recognition of the emotionally connoted stimuli. Thus, it is found an own-age bias phenomenon for healthy young and old participants in identification (not for Alzheimer’s subjects) and for healthy older adults and Alzheimer’s subjects in recognition (not for young people). Thus, the own-age bias phenomenon is not statistically found systematically despite trends. Thus, from this point of view, it can be hypothesized that the performance of participants, regardless of their age and health status (young adults, healthy elderly and Alzheimer’s subjects), will vary with the age of faces presented. Therefore it appears that this variable must be taken into account in a study involving exposure to face photographs. The limitations of this study (staffing and methodology) are to be taken into account in the interpretation of the results and may partly explain the fact that the own-age bias phenomenon is not found in all groups. Finally, concerning Alzheimer’s subjects, we can consider that their behavioral problems observed in everyday life may be partly explained by the fact that they hardly identify emotions and recognize faces less well.
Bibliography
Bortolon C., Louche A., Gely-Nargeot M-C. et Raffard S. (2015). Do patients suffering fom Alzheimer’s disease present an own-age-bias in face recognition ? Experimental Gerontology, 70, 46-53. doi: 10.1016/j.exger.2015.07.004.
