Accurate Judgment by Dementia Patients of Neutral Faces with Respect to Trustworthiness and Valence

Main aim of the present study was to investigate if dementia patients can make accurate social and affective judgments of face stimuli. We used verbal material as a control condition to see if dementia patients are capable of using the ratings scales the same way as controls. We compared trustworthiness, valence and arousal ratings of dementia patients with a healthy control group. Participants rated pictures of young and old, female and male neutral faces and two fictitious biographies. The results indicate that dementia patients make accurate judgments of unfamiliar faces with respect to trustworthiness and valence. Results concerning arousal ratings suggest that the corresponding scale might be difficult to use for dementia patients and possibly for older participants as well. Affective judgment in dementia 3 Accurate Judgment of Neutral Faces with Respect to Trustworthiness and Valence in Dementia Patients Behavior disturbances such as difficulties in social situations and inappropriate affective behavior are well known in dementia patients (Lyketsos et al., 2000). They can be a great burden for patients and caregivers. However, it is not clearly understood what causes these problems. Cognitive deficits have been studied extensively in this population and may contribute to behavior disturbances; patients have problems remembering names and events for example, which may lead to failures in social situations. Social withdrawal and depressive symptoms may arise in consequence. On the other hand deficits in emotion processing could be relevant for the occurrence of behavior disturbances as well, but little is known about emotion processing capacities of dementia patients. Dementia patients might for example have difficulties to interpret facial expressions of emotion or they might have difficulties in making accurate social and affective evaluations, which may both lead to inadequate reactions in social situations. Hence, the aim of the present study was to examine how dementia patients evaluate social and affective stimuli. To examine differences in emotion processing between healthy participants and individuals with dementia, face stimuli seem ideal, because they are of high relevance for social interactions. Results from studies focusing on the recognition of emotional facial expressions in dementia patients, however, are inconclusive: Some of the studies found a deficit in emotion recognition, others did not find such a deficit, and some attributed problems in emotion discrimination as shown by some patients to their deficits in other cognitive domains, or to global cognitive deterioration. For instance, Roudier et al. (1998) reported that AD patients are impaired in discriminating face stimuli, but are able to discriminate expressions of emotions. Affective judgment in dementia 4 Luzzi, Piccirilli, and Provinciali (2007) found that the ability to identify positive and negative emotions on chimeric faces is largely preserved in AD patients. In fact, impaired performance was found in only 27% of the subjects. Since the impaired participants had lower scores on constructional praxis and nonverbal memory tasks, the authors hypothesized that these patients represent a sub-group with predominant right-hemisphere dysfunction. Cadieux and Greve (1997) report a deficit in emotion recognition in AD and intact facial identity recognition. They attributed the deficits in emotion recognition to deficits in verbal and spatial processing in AD patients. Hargrave, Maddock, and Stone (2002) demonstrated that patients with AD have deficits in recognizing emotional facial expressions, and they concluded that these might be independent of their impairment in recognizing non-emotional features of faces. The recognition of emotional facial expressions is a critical aspect in social interactions and so is the accurate social judgment of other individuals based on their facial appearance. To our knowledge, no study has addressed the evaluation of face stimuli with regard to trustworthiness and the experience of adequate emotional reactions in dementia patients. However, difficulties of dementia patients in accurate social and affective judgment of other individuals on the basis of their facial appearances appear likely, given findings of amygdala damage in dementia patients (e.g., Kromer Vogt, Hyman, Van Hoesen, & Damasio, 1990). Studies with brain-damaged patients suggest that the amygdala is a critical structure for the accurate evaluation of neutral face stimuli with respect to trustworthiness and approachability (Adolphs, Tranel, & Damasio, 1998). Imaging studies also show that the amygdala is automatically activated in social judgment tasks (Winston, Strange, O ́Doherty, & Dolan, 2002). An important aspect in the investigation of affective and social judgments and possible differences between groups is the potential dissociation between face stimuli and verbal material. Affective judgment in dementia 5 Adolphs et al. (1998) reported that three patients with bilateral amygdala damage judged faces of unfamiliar people to be more trustworthy and approachable than controls. The impairment was greatest for faces to which normal subjects assigned the most negative ratings. However, there was no impairment when verbal descriptions of people were evaluated. The amygdala seems to be necessary to trigger the retrieval of information that is based on prior experience with certain stimuli or potentially an innate response bias (Damasio, 1995). Verbal information seems to evoke enough information to perform judgments accurately without the assistance of the amygdala. Thus, accurate judgment of verbal material seems to rely more on cognitive processes. Since the aim of our study was to investigate social and affective judgments that are based on prior experience with certain stimuli or an innate response bias in dementia patients we used unfamiliar neutral faces as stimuli. We did not use faces displaying emotions in the present study, because a previous study (Winston et al. 2002) found correlations between perceived trustworthiness ratings and facial expressions of some emotions. To ensure that ratings are not influenced by participants’ ability to recognise facial expressions of emotions we used only neutral faces. Verbal material was used as a control condition. If ratings of face stimuli of healthy subjects and dementia patients do not differ, this would indicate that affective evaluation is intact in dementia patients. However, if ratings of dementia patients and controls differ on certain dimensions, this could be due to cognitive deficits, that is difficulties using rating scales or affective processing deficits. We hypothesized that if the dementia patients in our study are unable to make accurate affective and social judgments of verbal material, their difficulties might be related to general cognitive decline and associated difficulties using rating scales. However, if they do not judge face stimuli accurately, but are able to accurately judge the verbal material, this would indicate emotion processing deficits in dementia patients. Affective judgment in dementia 6 We compared affective evaluations of patients with dementia with those invited from a healthy, age-matched control group using both verbal material and face stimuli. Participants rated pictures of 12 young and old, female and male neutral faces on the dimensions of valence, arousal and trustworthiness, and two fictitious biographies, one containing positive the other negative traits. Design and Methods