Do children utilize motion when recognizing faces?

Previous research indicates that unfamiliar faces may be recognized better if they are viewed in motion. This study utilized a three trial learning paradigm to investigate whether unfamiliar faces are learnt more quickly from moving clips than from static images. Children aged 6–7 years and 10–11 years were shown a series of faces as either static images or dynamic clips, followed by either by a static or a dynamic recognition test. Faces were recognized more accurately when presented in motion, but there was no advantage for testing in motion. Although older children were more accurate overall, younger females performed as well as older children for faces presented in motion, suggesting that females’ face processing skills develop more quickly than those of males. Results are discussed in terms of the motion advantage arising due to additional structural information enhancing the internal representation of the face.     

Repetition priming from moving faces

Recent experiments have suggested that seeing a familiar face move provides additional dynamic information to the viewer, useful in the recognition of identity. In four experiments, repetition priming was used to investigate whether dynamic information is intrinsic to the underlying face representations. The results suggest that a moving image primes more effectively than a static image, even when the same static image is shown in the prime and the test phases (Experiment 1). Furthermore, when moving images are presented in the test phase (Experiment 2), there is an advantage for moving prime images. The most priming advantage is found with naturally moving faces, rather than with those shown in slow motion (Experiment 3). Finally, showing the same moving sequence at prime and test produced more priming than that found when different moving sequences were shown (Experiment 4). The results suggest that dynamic information is intrinsic to the face representations and that there is an advantage to viewing the same moving sequence at prime and test.     

Exploring the role of characteristic motion when learning new faces

Previous research has shown that it is easier to recognize familiar faces when shown moving, rather than static, especially when viewing conditions are difficult (Knight & Johnston, 1997; Lander, Christie, & Bruce, 1999). One possible theoretical reason for the moving-face advantage is that we learn "characteristic motion signatures" for familiar faces, associated with the face representation in memory. To examine this idea we investigated the role of motion at test when learning faces from either static images or moving sequences (Experiment 1). Results suggest that there is only an advantage for motion at test when the face is learned moving. In Experiment 2 we map the importance of facial motion as a face becomes increasingly familiar, on a television drama. We demonstrate that the beneficial effect of motion is not dependent on the amount of time the face is viewed. Results from both experiments support the idea of rapidly learned characteristic motion patterns.     

Why are moving faces easier to recognize?

Previous work has suggested that seeing a famous face move aids the recognition of identity, especially when viewing conditions are degraded (Knight & Johnston, ; Lander, Christie, & Bruce, ). Experiment 1 investigated whether the beneficial effects of motion are related to a particular type of facial motion (expressing, talking, or rigid motion). Results showed a significant beneficial effect of both expressive and talking movements, but no advantage for rigid motion, compared with a single static image. Experiment 2 investigated whether the advantage for motion is uniform across identity. Participants rated moving famous faces for distinctiveness of motion. The famous faces (moving and static freeze frame) were then used as stimuli in a recognition task. The advantage for face motion was significant only when the motion displayed was distinctive. Results suggest that a reason why moving faces are easier to recognize is because some familiar faces have characteristic motion patterns, which act as an additional cue to identity.     

A matching advantage for dynamic human faces

In a series of three experiments, we used a sequential matching task to explore the impact of non-rigid facial motion on the perception of human faces. Dynamic prime images, in the form of short video sequences, facilitated matching responses relative to a single static prime image. This advantage was observed whenever the prime and target showed the same face but an identity match was required across expression (experiment 1) or view (experiment 2). No facilitation was observed for identical dynamic prime sequences when the matching dimension was shifted from identity to expression (experiment 3). We suggest that the observed dynamic advantage, the first reported for non-degraded facial images, arises because the matching task places more emphasis on visual working memory than typical face recognition tasks. More specifically, we believe that representational mechanisms optimised for the processing of motion and/or change-over-time are established and maintained in working memory and that such 'dynamic representations' (Freyd, 1987 Psychological Review 94 427-438) capitalise on the increased information content of the dynamic primes to enhance performance.     

The attentional boost effect really is a boost: Evidence from a new baseline

In the attentional boost effect, participants encode images into memory as they perform an unrelated target-detection task. Later memory is better for images that coincided with a target rather than a distractor. This advantage could reflect a broad processing enhancement triggered by target detection, but it could also reflect inhibitory processes triggered by distractor rejection. To test these possibilities, in four experiments we acquired a baseline measure of image memory when neither a target nor a distractor was presented. Participants memorized faces presented in a continuous series (500- or 100-ms duration). At the same time, participants monitored a stream of squares. Some faces appeared on their own, and others coincided with squares in either a target or a nontarget color. Because the processes associated with both target detection and distractor rejection were minimized when faces appeared on their own, this condition served as a baseline measure of face encoding. The data showed that long-term memory for faces coinciding with a target square was enhanced relative to faces in both the baseline and distractor conditions. We concluded that detecting a behaviorally relevant event boosts memory for concurrently presented images in dual-task situations.     

Exploring the memory advantage for moving scenes

Recognition memory is better for moving images than for static images (the dynamic superiority effect), and performance is best when the mode of presentation at test matches that at study (the study–test congruence effect). We investigated the basis for these effects. In Experiment 1, dividing attention during encoding reduced overall performance but had little effect on the dynamic superiority or study–test congruence effects. In addition, these effects were not limited to scenes depicting faces. In Experiment 2, movement improved both old–new recognition and scene orientation judgements. In Experiment 3, movement improved the recognition of studied scenes but also increased the spurious recognition of novel scenes depicting the same people as studied scenes, suggesting that movement increases the identification of individual objects or actors without necessarily improving the retrieval of associated information. We discuss the theoretical implications of these results and highlight directions for future investigation.     

The State of Ecological Psychology

We report on two experiments that investigated the role of facial motion in the recognition of degraded famous face images. The results of these experiments suggest that seeing a face move is advantageous for the correct recognition of identity. This effect is not solely due to the extra static-based information contained in a moving sequence but is also due to additional dynamic information available from a moving face. Furthermore, famous faces were recognized more accurately when the original dynamic characteristics of the motion were maintained (Experiment 1), compared to when either the tempo or the direction of motion were altered (Experiment 2). It is suggested that there may be general benefit for viewing naturally moving faces, not specific benefit to any particular face identity. Alternatively, individual faces may have associated characteristic motion signatures.     

The role of motion and speech in face recognition at birth

Newborns, a few hours after birth, already encounter many different faces, talking or silently moving. How do they process these faces and which cues are important in early face recognition? In a series of six experiments, newborns were familiarized with an unfamiliar face in different contexts (photographs, talking, silently moving, and with only external movements of the head with speech sound). At test, they saw the familiar and a new faces either in photographs, silently moving, or talking. A novelty preference was evidenced at test when photographs were presented in the two phases. This result supports those already evidenced in several studies. A familiarity preference appeared only when the face was seen talking in the familiarization phase and in a photograph or talking again at test. This suggests that the simultaneous presence of speech sound, and rigid and nonrigid movements present in a talking face enhances recognition of interactive faces at birth.     

Learning the moves: the effect of familiarity and facial motion on person recognition across large changes in viewing format

Familiarity with a face or person can support recognition in tasks that require generalization to novel viewing contexts. Using naturalistic viewing conditions requiring recognition of people from face or whole body gait stimuli, we investigated the effects of familiarity, facial motion, and direction of learning/test transfer on person recognition. Participants were familiarized with previously unknown people from gait videos and were tested on faces (experiment 1a) or were familiarized with faces and were tested with gait videos (experiment 1b). Recognition was more accurate when learning from the face and testing with the gait videos, than when learning from the gait videos and testing with the face. The repetition of a single stimulus, either the face or gait, produced strong recognition gains across transfer conditions. Also, the presentation of moving faces resulted in better performance than that of static faces. In experiment 2, we investigated the role of facial motion further by testing recognition with static profile images. Motion provided no benefit for recognition, indicating that structure-from-motion is an unlikely source of the motion advantage found in the first set of experiments.     

The influence of indirect and direct emotional processing on memory for facial expressions

We used the remember-know procedure (Tulving, 1985 ) to test the behavioural expression of memory following indirect and direct forms of emotional processing at encoding. Participants (N=32) viewed a series of facial expressions (happy, fearful, angry, and neutral) while performing tasks involving either indirect (gender discrimination) or direct (emotion discrimination) emotion processing. After a delay, participants completed a surprise recognition memory test. Our results revealed that indirect encoding of emotion produced enhanced memory for fearful faces whereas direct encoding of emotion produced enhanced memory for angry faces. In contrast, happy faces were better remembered than neutral faces after both indirect and direct encoding tasks. These findings suggest that fearful and angry faces benefit from a recollective advantage when they are encoded in a way that is consistent with the predictive nature of their threat. We propose that the broad memory advantage for happy faces may reflect a form of cognitive flexibility that is specific to positive emotions.     

The effect of motion at encoding and retrieval for same- and other-race face recognition

In an experimental study, we assessed the role of motion when encoding and recognizing unfamiliar faces, using an old/new recognition memory paradigm. Our findings revealed a clear advantage for learning unfamiliar faces moving non-rigidly, compared with static faces. This advantage for motion was found with both same- and other-race faces. Furthermore, results indicate that it is more important that the face is learnt in motion than recognized from a moving clip. Interestingly, despite a reliable other-race effect being revealed, participants were able to utilize motion information exhibited by other-race faces in a manner akin to the motion advantage found for same-race faces. The implications of these findings are discussed in relation to the nature of the stored face representations, considering whether the facilitative role found here can be explained by factors other than motion per se.     

The effect of noun animacy on the processing of unambiguous sentences: Evidence from French relative clauses

It has previously been shown that moving images are remembered better than static ones. In two experiments, we investigated the basis for this dynamic superiority effect. Participants studied scenes presented as a single static image, a sequence of still images, or a moving video clip, and 3 days later completed a recognition test in which familiar and novel scenes were presented in all three formats. We found a marked congruency effect: For a given study format, accuracy was highest when test items were shown in the same format. Neither the dynamic superiority effect nor the study–test congruency effect was affected by encoding (Experiment 1) or retrieval (Experiment 2) manipulations, suggesting that these effects are relatively impervious to strategic control. The results demonstrate that the spatio-temporal properties of complex, realistic scenes are preserved in long-term memory.     

The role of movement in the recognition of famous faces

The effects of movement on the recognition of famous faces shown in difficult conditions were investigated. Images were presented as negatives, upside down (inverted), and thresholded. Results indicate that, under all these conditions, moving faces were recognized significantly better than static ones. One possible explanation of this effect could be that a moving sequence contains more static information about the different views and expressions of the face than does a single static image. However, even when the amount of static information was equated (Experiments 3 and 4), there was still an advantage for moving sequences that contained their original dynamic properties. The results suggest that the dynamics of the motion provide additional information, helping to access an established familiar face representation. Both the theoretical and the practical implications for these findings are discussed.     

Evaluating the effectiveness of pixelation and blurring on masking the identity of familiar faces

Two experiments are reported that assess how well the identity of highly familiar (famous) faces can be masked from short naturalistic television clips. Recognition of identity was made more difficult by either pixelating (Experiment 1) or blurring (Experiment 2) the viewed face. Participants were asked to identify faces from both moving and static clips. Results indicated that participants were still able to recognize some of the viewed faces, despite these image degradations. In addition, moving images of faces were recognized better than static ones. The practical and theoretical implications of these findings are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

The role of motion in learning new faces

Four experiments are reported that investigate the usefulness of rigid (head nodding, shaking) and nonrigid (talking, expressions) motion for establishing new face representations of previously unfamiliar faces. Results show that viewing a face in motion leads to more accurate face learning, compared with viewing a single static image (Experiment 1). The advantage for viewing the face moving rigidly seems to be due to the different angles of view contained in these sequences (Experiment 2). However, the advantage for nonrigid motion is not simply due to multiple images (Experiment 3) and is not specifically linked to forwards motion but extends to reversed sequences (Experiment 4). Thus, although we have demonstrated beneficial effects of motion for face learning, they do not seem to be due to the specific dynamic properties of the sequences shown. Instead, the advantage for nonrigid motion may reflect increased attention to faces moving in a socially important manner.     

Getting to know you: How we learn new faces

Previous work has shown an advantage for matching the internal features of familiar faces in contrast to an advantage for the external features of unfamiliar faces. In the current experiment, we tracked this shift towards an internal feature advantage as subjects were familiarized with a set of initially unfamiliar faces. They were asked to learn a set of 24 faces from video images and complete a face matching task on 3 consecutive days. Half of the faces were learned from moving images while the others were learned from static images to determine whether movement was necessary to produce the internal advantage found when matching familiar faces. We found that by the end of the 3 days, performance on the internal features had improved and was equivalent to performance on the external features. In contrast, matching of the external features remained at a relatively constant level across the experiment. Faces were learned equally well from moving and static images suggesting that movement is not necessary to promote learning of the internal features.     

Spatial reference in multiple object tracking

Spatial reference in multiple object tracking is available from configurations of dynamic objects and static reference objects. In three experiments, we studied the use of spatial reference in tracking and in relocating targets after abrupt scene rotations. Observers tracked 1, 2, 3, 4, and 6 targets in 3D scenes, in which white balls moved on a square floor plane. The floor plane was either visible thus providing static spatial reference or it was invisible. Without scene rotations, the configuration of dynamic objects provided sufficient spatial reference and static spatial reference was not advantageous. In contrast, with abrupt scene rotations of 20°, static spatial reference supported in relocating targets. A wireframe floor plane lacking local visual detail was as effective as a checkerboard. Individually colored geometric forms as static reference objects provided no additional benefit either, even if targets were centered on these forms at the abrupt scene rotation. Individualizing the dynamic objects themselves by color for a brief interval around the abrupt scene rotation, however, did improve performance. We conclude that attentional tracking of moving targets proceeds within dynamic configurations but detached from static local background.     

Recognizing face identity from natural and morphed smiles

It is easier to identify a degraded familiar face when it is shown moving (smiling, talking; nonrigid motion), than when it is displayed as a static image (Knight & Johnston, 1997; Lander, Christie, & Bruce, 1999). Here we explore the theoretical underpinnings of the moving face recognition advantage. In Experiment 1 we show that the identification of personally familiar faces when shown naturally smiling is significantly better than when the person is shown artificially smiling (morphed motion), as a single static neutral image or as a single static smiling image. In Experiment 2 we demonstrate that speeding up the motion significantly impairs the recognition of identity from natural smiles, but has little effect on morphed smiles. We conclude that the recognition advantage for face motion does not reflect a general benefit for motion, but suggests that, for familiar faces, information about their characteristic motion is stored in memory.