Grit Herzmann

Individual Differences in Perceiving and Recognizing Faces—One Element of Social Cognition

Recognizing faces swiftly and accurately is of paramount importance to humans as a social species. Individual differences in the ability to perform these tasks may therefore reflect important aspects of social or emotional intelligence. Although functional models of face cognition based on group and single case studies postulate multiple component processes, little is known about the ability structure underlying individual differences in face cognition. In 2 large individual differences experiments (N = 151 and N = 209), a broad variety of face-cognition tasks were tested and the component abilities of face cognition-face perception, face memory, and the speed of face cognition-were identified and then replicated. Experiment 2 also showed that the 3 face-cognition abilities are clearly distinct from immediate and delayed memory, mental speed, general cognitive ability, and object cognition. These results converge with functional and neuroanatomical models of face cognition by demonstrating the difference between face perception and face memory. The results also underline the importance of distinguishing between speed and accuracy of face cognition. Together our results provide a first step toward establishing face-processing abilities as an independent ability reflecting elements of social intelligence.

Toward a comprehensive test battery for face cognition: Assessment of the tasks

Despite the importance of face recognition in everyday life and frequent complaints about its failure, there is no comprehensive test battery for this ability. As a first step in constructing such a battery, we present 18 tasks aimed at measuring face perception, face learning, face recognition, and the recognition of facially expressed emotions. A sample of 153 healthy young adults completed all tasks. In general, reaction time measures showed high estimates of internal consistency; tasks focused on performance accuracy yielded reliabilities that were somewhat lower, yet high enough to support their use in a battery of face cognition measures. Some of the tasks allowed computation of established experimental effects in a within-subjects design, such as the part-whole effect. Most of these experimental effects were confirmed in our large sample, and valuable effect size estimates were obtained. However, in many cases these difference measures showed poor estimates of internal consistency.

Individual differences in face cognition: Brain-behavior relationships

Individual differences in perceiving, learning, and recognizing faces, summarized under the term face cognition, have been shown on the behavioral and brain level, but connections between these levels have rarely been made. We used ERPs in structural equation models to determine the contributions of neurocognitive processes to individual differences in the accuracy and speed of face cognition as established by Wilhelm, Herzmann, Kunina, Danthiir, Schacht, and Sommer [Individual differences in face cognition, in press]. For 85 participants, we measured several ERP components and, in independent tasks and sessions, assessed face cognition abilities and other cognitive abilities, including immediate and delayed memory, mental speed, general cognitive ability, and object cognition. Individual differences in face cognition were unrelated to domain-general visual processes (P100) and to processes involved with memory encoding (Dm component). The ability of face cognition accuracy was moderately related to neurocognitive indicators of structural face encoding (latency of the N170) and of activating representations of both faces and person-related knowledge (latencies and amplitudes of the early and late repetition effects, ERE/N250 and LRE/N400, respectively). The ability of face cognition speed was moderately related to the amplitudes of the ERE and LRE. Thus, a substantial part of individual differences in face cognition is explained by the speed and efficiency of activating memory representations of faces and person-related knowledge. These relationships are not moderated by individual differences in established cognitive abilities.

Effects of previous experience and associated knowledge on retrieval processes of faces: An ERP investigation of newly learned faces

Conspicuously absent from face recognition research is a direct comparison of well-known faces with newly learned faces for which the associated biographical knowledge and the perceptual expertise were experimentally manipulated. Such a comparison can test competing assumptions made by serial and interactive activation and competition (IAC) models about the role of previous experience and biographical knowledge in face recognition. We measured behavioral performance and event-related potentials (ERPs) for four classes of faces: unfamiliar faces, faces of celebrities, and two classes of experimentally familiarized faces learned one week prior to the recognition test either with or without associated biographical knowledge. Newly learned faces associated with biographical knowledge showed distinct priming and old/new effects starting around 420 ms in the ERP when compared to faces without such information, and when compared to famous faces. In addition, faces for which all biographical facts were successfully remembered showed not only faster recognition performance than faces without biographical knowledge, but also a priming effect in the N170 latency. Previous experience including biographical knowledge associated with a face thus influenced retrieval processes of faces both in late, semantic and early, pre-semantic processing stages. These findings provide novel evidence in favor of IAC models. In addition, famous faces had the same ERP effects as faces learned without associated facts. Our results show that newly learned faces are experimentally indistinguishable from famous faces yet provide superior experimental control.

Face and Object Cognition Across Adult Age

We investigated the specificity of face compared with object cognition from an individual differences and aging perspective by determining the amount of overlap between these abilities at the level of latent constructs across age. Confirmatory factor analytic models tested the specificity of speed and accuracy measures for face and object cognition (N = 448; 18 to 88 years). Accuracy measures were distinguishable and slightly dedifferentiated across age, which was not due to loss of visual acuity and contrast sensitivity. There was no face specificity for speed measures. These results support the specificity of face cognition from differential and developmental perspective only for performance accuracy.

Can Training Enhance Face Cognition Abilities in Middle-Aged Adults?

Face cognition is a crucial skill for social interaction and shows large individual differences in healthy adults, suggesting a possibility for improvement in some. We developed and tested specific training procedures for the accuracy of face memory and the speed of face cognition. Two groups each of 20 healthy middle-aged trainees practiced for 29 daily sessions of 15 minutes duration with different computerized home-based training procedures. In addition, 20 matched and 59 non-matched controls were included. Face cognition speed training enhanced performance during the training and transferred to the latent factor level as measured in a pre-post comparison. Persistence of the training effect was evidenced at the manifest level after three months. However, the training procedure influenced the speed of processing object stimuli to the same extent as face stimuli and therefore seems to have affected a more general ability of processing complex visual stimuli and not only faces. No effects of training on the accuracy of face memory were found. This study demonstrates that face-specific abilities may be hard to improve but also shows the plasticity of the speed of processing complex visual stimuli – for the first time in middle-aged, normal adults.

Neural correlates of the in-group memory advantage on the encoding and recognition of faces.

People have a memory advantage for faces that belong to the same group, for example, that attend the same university or have the same personality type. Faces from such in-group members are assumed to receive more attention during memory encoding and are therefore recognized more accurately. Here we use event-related potentials related to memory encoding and retrieval to investigate the neural correlates of the in-group memory advantage. Using the minimal group procedure, subjects were classified based on a bogus personality test as belonging to one of two personality types. While the electroencephalogram was recorded, subjects studied and recognized faces supposedly belonging to the subject’s own and the other personality type. Subjects recognized in-group faces more accurately than out-group faces but the effect size was small. Using the individual behavioral in-group memory advantage in multivariate analyses of covariance, we determined neural correlates of the in-group advantage. During memory encoding (300 to 1000 ms after stimulus onset), subjects with a high in-group memory advantage elicited more positive amplitudes for subsequently remembered in-group than out-group faces, showing that in-group faces received more attention and elicited more neural activity during initial encoding. Early during memory retrieval (300 to 500 ms), frontal brain areas were more activated for remembered in-group faces indicating an early detection of group membership. Surprisingly, the parietal old/new effect (600 to 900 ms) thought to indicate recollection processes differed between in-group and out-group faces independent from the behavioral in-group memory advantage. This finding suggests that group membership affects memory retrieval independent of memory performance. Comparisons with a previous study on the other-race effect, another memory phenomenon influenced by social classification of faces, suggested that the in-group memory advantage is dominated by top-down processing whereas the other-race effect is also influenced by extensive perceptual experience.

Neural correlates of memory encoding and recognition for own-race and other-race faces in an associative-memory task

The ability to recognize faces of family members, friends, and acquaintances plays an important role in our daily interactions. The other-race effect is the reduced ability to recognize other-race faces as compared to own-race faces. Previous studies showed different patterns of event-related potentials (ERPs) associated with recollection and familiarity during memory encoding (i.e., Dm) and recognition (i.e., parietal old/new effect) for own-race and other-race faces in a subjective-recollection task (remember-know judgments). The present study investigated the same neural correlates of the other-race effect in an associative-memory task, in which Caucasian and East Asian participants learned and recognized own-race and other-race faces along with background colors. Participants made more false alarms for other-race faces indicating lower memory performance. During the study phase, subsequently recognized other-race faces (with and without correct background information) elicited more positive mean amplitudes than own-race faces, suggesting increased neural activation during encoding of other-race faces. During the test phase, recollection-related old/new effects dissociated between own-race and other-race faces. Old/new effects were significant only for own-race but not for other-race faces, indicating that recognition only of own-race faces was supported by recollection and led to more detailed memory retrieval. Most of these results replicated previous studies that used a subjective-recollection task. Our study also showed that the increased demand on memory encoding during an associative-memory task led to Dm patterns that indicated similarly deep memory encoding for own-race and other-race faces.

Neural evidence for the contribution of holistic processing but not attention allocation to the other-race effect on face memory

Multiple mechanisms have been suggested to contribute to the other-race effect on face memory, the phenomenon of better memory performance for own-race than other-race faces. Here, two of these mechanisms, increased attention allocation and greater holistic processing during memory encoding for own-race than other-race faces, were tested in two separate experiments. In these experiments event-related potentials were measured during study (the difference due to memory, Dm) and test phase (old/new effects) to examine brain activation related to memory encoding and retrieval, allowing for selective investigations of these memory sub-processes. In Experiment 1, participants studied own-race (Caucasian) and other-race (Chinese) faces under focused or divided attention. In Experiment 2, participants studied own-race (Caucasian) and other-race (African American) faces presented upright or upside down (i.e., inverted). Both experiments showed decreases in memory performance when attention allocation or holistic processing was reduced, but these effects were similar for own-race and other-race faces. Manipulations of holistic processing, but not attention allocation, influenced the neural other-race effects during memory encoding. Inverted own-race faces showed similar neural patterns as upright other-race faces, indicating that when holistic processing of own-race faces was reduced, these faces were encoded similarly as upright other-race faces. No influences of the experimental manipulations on other-race effects during memory retrieval were found. The present study provides the first neural evidence that increased holistic processing during memory encoding contributes to the other-race effect on face memory.

The neural correlates of categorization and individuation of own-race and other-race faces

Categorization and individuation of own-race and other-race faces consistently leads to opposite effects. Categorization is faster for other-race faces, individation is faster for own-race faces. Explanations for these findings suggest that own-race faces are processed on the level of the individuum in both tasks which hampers categorization but facilitates individuation. They also suggest a lack of holistic processing for other-race faces which is proposed to be due to either a lack of motivation according to socio-cognitive theories or a lack of perceptual learning according to perceptual expertise theories. This study recorded event-related potentials while Caucasian participants matched two sequentially presented faces based on race (categorization) or identity (individuation). Face stimuli consisted of Caucasian faces, Chinese faces, and African-American faces. Confirming previous findings, other-race faces were categorized faster but individuated slower than own-race faces. The N250, taken to reflect individuation or subordinate level processing, yielded three important findings. First, it was largest for other-race faces in both tasks showing that individuation of other-race faces requires more neural resources and speaks against a motivational cause for the lack of holistic processing and thus socio-cognitive theories. Second, African-American faces elicited larger N250 amplitudes than Chinese faces in the categorization task but not in the individuation task suggesting a special role of skin color during categorization but not individuation. Finally, sequential (i.e., repeated) presentation of the faces influenced the N250. For own-race faces, N250 repetition effects were the same in both tasks. For other-race faces, N250 repetition effects were larger in the individuation than the categorization task. These results provide evidence that own-race faces are processed in the same way in both tasks. They also provide further evidence against socio-cognitive theories because a larger repetition effect in the individuation task for other-race faces is in contrast to the proposed motivational lack for holistic processing. Meeting abstract presented at VSS 2015.