Conscious control and memory awareness when recognising famous faces

We describe an experiment that investigated levels-of-processing effects in recognition memory for famous faces. The degree of conscious control over the recognition decisions was manipulated by using a response deadline procedure, and memory awareness associated with those decisions was assessed using a standard remember-know paradigm. Levels-of-processing effects were found at both short and long response deadlines, and at both deadlines those effects occurred only in remembering. Moreover, knowing, as well as remembering, increased with the greater opportunity for conscious control over recognition decisions at the long deadline. These results have implications for dual-process theories that distinguish between a slower, more controlled recollection process, reflected in remembering, and a faster, more automatic familiarity process, reflected in knowing.     

The effects of distinctiveness in recognising and classifying faces

In an earlier study it was found that distinctive familiar faces were recognised faster than typical familiar faces in a familiarity decision task. In the first experiment reported here this effect was replicated with the use of celebrities' faces rather than personally familiar faces. In the second and third experiments the effect of distinctiveness was found to reverse if the task was to distinguish between faces and jumbled faces. Subjects took longer to classify distinctive faces as faces than they did to classify typical faces. Thus distinctive faces were recognised faster, but were classified as faces more slowly than were typical faces, both when personally familiar faces and when famous faces were used as stimuli. These results are interpeted as evidence that faces are encoded by reference to a general face prototype.     

The effects of different types of encoding task on memory for famous faces and names

In this study, incidental memory for familiar faces following different types of encoding task was investigated. Subjects who had been asked to name faces of celebrities at presentation subsequently remembered them significantly better than subjects who had been asked to provide contextual information about the faces, and than subjects who had been asked to distinguish them from unfamiliar faces. This effect persisted regardless of whether the tests required memory for names, faces, or biographical information. It is argued that these results can be explained in terms of the face-processing framework of Bruce and Young (1986) and the theory of episodic memory for faces put forward by Bruce (1982, 1988). However the findings are not consistent with levels of processing (Craik & Lockhart, 1972), nor transfer appropriate processing (Morris, Bransford, & Franks, 1977).     

Conscious awareness of action potentiates sensorimotor learning

Many everyday skills are unconsciously learned through repetitions of the same behaviour by binding independent motor acts into unified sets of actions. However, our ability to be consciously aware of producing newly and highly trained motor skills raises the question of the role played by conscious awareness of action upon skill acquisition. In this study we strengthened conscious awareness of self-produced sequential finger movements by way of asking participants to judge their performance in terms of maximal fluency after each trial. Control conditions in which participants did not make any judgment or performance-unrelated judgments were also included. Findings indicate that conscious awareness of action, enhanced via subjective appraisal of motor efficiency, potentiates sensorimotor learning and skilful motor production in optimising the processing and sequencing of action units, as compared to the control groups. The current work lends support to the claim that the learning and skilful expression of sensorimotor behaviours might be grounded upon our ability to be consciously aware of our own motor capability and efficiency.     

Recalling episodic and semantic information about famous faces and voices

In this study, we used the distinction between remember and know (R/K) recognition responses to investigate the retrieval of episodic information during familiar face and voice recognition. The results showed that familiar faces presented in standard format were recognized with R responses on approximately 50% of the trials. The corresponding figure for voices was less than 20%. Even when overall levels of recognition were matched between faces and voices by blurring the faces, significantly more R responses were observed for faces than for voices. Voices were significantly more likely to be recognized with K responses than were blurred faces. These findings indicate that episodic information was recalled more often from familiar faces than from familiar voices. The results also showed that episodic information about a familiar person was never recalled unless some semantic information, such as the person's occupation, was also retrieved.     

Accuracy of familiarity decisions to famous faces perceived without awareness depends on attitude to the target person and on response latency

Stone and Valentine (2004) presented masked 17 ms faces in simultaneous pairs of one famous and one unfamiliar face. Accuracy in selecting the famous face was higher when the famous person was regarded as "good" or liked than when regarded as "evil" or disliked. Experiment 1 attempted to replicate this phenomenon, but produced a different pattern of results. Experiment 2 investigated alternative explanations and found evidence supporting only the effect of response latency: responses made soon after stimulus onset were more accurate to liked than to disliked faces, whereas responses made after a longer delay were equally accurate to disliked faces. It appears that the effect of negative valence was corrected within the space of a few hundred milliseconds. Experiment 3, using an affective priming paradigm, supported the concept that an early-arising effect of valence is corrected if it is misleading to the directed task.     

Conscious awareness is required for holistic face processing

Investigating the limits of unconscious processing is essential to understand the function of consciousness. Here, we explored whether holistic face processing, a mechanism believed to be important for face processing in general, can be accomplished unconsciously. Using a novel “eyes-face” stimulus we tested whether discrimination of pairs of eyes was influenced by the surrounding face context. While the eyes were fully visible, the faces that provided context could be rendered invisible through continuous flash suppression. Two experiments with three different sets of face stimuli and a subliminal learning procedure converged to show that invisible faces did not influence perception of visible eyes. In contrast, surrounding faces, when they were clearly visible, strongly influenced perception of the eyes. Thus, we conclude that conscious awareness might be a prerequisite for holistic face processing.     

Positive facial affect facilitates the identification of famous faces

Several convergent lines of evidence have suggested that the presence of an emotion signal in a visual stimulus can influence processing of that stimulus. In the current study, we picked up on this idea, and explored the hypothesis that the presence of an emotional facial expression (happiness) would facilitate the identification of familiar faces. We studied two groups of normal participants (overall N=54), and neurological patients with either left (n=8) or right (n=10) temporal lobectomies. Reaction times were measured while participants named familiar famous faces that had happy expressions or neutral expressions. In support of the hypothesis, naming was significantly faster for the happy faces, and this effect obtained in the normal participants and in both patient groups. In the patients with left temporal lobectomies, the effect size for this facilitation was large (d=0.87), suggesting that this manipulation might have practical implications for helping such patients compensate for the types of naming defects that often accompany their brain damage. Consistent with other recent work, our findings indicate that emotion can facilitate visual identification, perhaps via a modulatory influence of the amygdala on extrastriate cortex.     

Ignoring famous faces: category-specific dilution of distractor interference

The extent to which famous distractor faces can be ignored was assessed in six experiments. Subjects categorized famous printed target names as those of pop stars or politicians, while attempting to ignore a flanking famous face distractor that could be congruent (e.g, a politician's name and face) or incongruent (e.g., a politician's name with a pop stars face). Congruency effects on reaction times indicated distractor intrusion. An additional, response-neutral flanker (neither pop star nor politician) could also be present. Congruency effects from the critical distractor face were reduced (diluted) by the presence of an intact anonymous face, but not by phase-shifted versions, inverted faces, or meaningful nonface objects. By contrast, congruency effects from other types of distracting objects (musical instruments, fruits), when printed names for these classes were categorized, were diluted equivalently by intact faces, phase-shifted faces, or meaningful nonface objects. Our results suggest that distractor faces act differently from other types of distractors, suffering from only face-specific capacity limits.     

Right hemisphere superiority in the recognition of famous faces

Words and famous faces were tachistoscopically presented in bilateral view to normal right-handed subjects. A left visual field advantage was obtained for famous faces whether naming or recognition from an array was required and a right visual field advantage was obtained for words. While the finding of a left visual field advantage for the recognition of famous faces is consistent with studies of face recognition deficits in brain-damaged patients, a right visual field advantage for the recognition of famous faces has recently been reported in normal subjects. Possible explanations for this discrepancy are discussed.     

Aging and memory for faces versus single views of faces

Differences in the ability of young adults and elderly to recognize faces were examined under two conditions. In a standard single-view condition, in which each input face was shown as one photograph, we confirmed prior findings that young adults perform better than the elderly at distinguishing photographs seen before from photographs of new faces. We also found that the elderly had more trouble distinguishing photographs seen before from photographs of(l) old faces changed in facial expression and (2) old faces changed in expression and pose. Yet there were no reliable age differences in distinguishing old-but-changed faces from entirely new faces. In a more naturalistic multi-view condition, in which each input face was shown in four poses and with two expressions, no age differences were found. A second experiment ruled out the possibility that varied repetition, by itself, removes age differences in recognizing faces. These data supported age differences in remembering facial expressions and possibly other details of photographs of faces, but not in remembering faces perse.     

Visual awareness and the detection of fearful faces

A commonly held view is that emotional stimuli are processed independently of awareness. Here, the authors parametrically varied the duration of a fearful face target stimulus that was backward masked by a neutral face. The authors evaluated awareness by characterizing behavioral performance using receiver operating characteristic curves from signal detection theory. Their main finding was that no universal objective awareness threshold exists for fear perception. Although several subjects displayed a behavioral pattern consistent with previous reports (i.e., targets masked at 33 ms), a considerable percentage of their subjects (64%) were capable of reliably detecting 33-ms targets. Their findings suggest that considerable information is available even in briefly presented stimuli (possibly as short as 17 ms) to support masked fear detection.     

Implicit memory and test awareness

In three experiments we examined whether normal subjects can perform an implicit test without becoming aware that the test items were previously encountered in the study phase of the experiment. Experiment 1 assessed single word priming with the stem completion task, and subjects who reported awareness/unawareness that the test items were previously encoded in the study task showed equivalent priming. Experiments 2a-c and 3 assessed associative priming with the stem completion task, and in this case, only subjects who were aware that the test items were previously encountered showed associative priming effects. These findings suggest that single word priming and associative priming reflect different memory processes because the former and not the latter effect can be observed in unaware subjects.     

Laterality effects in identification of caricatures and photographs of famous faces

Recent evidence suggests that memory representations of familiar faces may exaggerate distinctive information as do caricatures (G. Rhodes, S. Brennan, & S. Carey, Cognitive Psychology, 1987). Therefore caricatures should be effective representations of faces and should yield a right hemisphere processing advantage, as do photographs of faces. Photographs and caricatures of famous faces were presented to the left visual (LVF), the right visual field (RVF), and centrally (CVF), in a name-face verification task. There was a LVF (right hemisphere) advantage for both caricatures and photographs on name-face mismatches but no VF difference for matches. These results were true for both accuracy and reaction time. Processing strategy differences that may account for the difference between matches and mismatches are discussed. Performance was generally better for photographs than for caricatures, irrespective of visual field condition.     

Semantic priming in the name retrieval of objects and famous faces

Researchers interested in face processing have recently debated whether access to the name of a known person occurs in parallel with retrieval of semantic‐biographical codes, rather than in a sequential fashion. Recently, Schweinberger, Burton, and Kelly (2001) took a failure to obtain a semantic context effect in a manual syllable judgment task on names of famous faces as support for this position. In two experiments, we compared the effects of visually presented categorically related prime words with either objects (e.g. prime: animal; target: dog) or faces of celebrities (e.g. prime: actor; target: Bruce Willis) as targets. Targets were either manually categorized with regard to the number of syllables (as in Schweinberger et al.), or they were overtly named. For neither objects nor faces was semantic priming obtained in syllable decisions; crucially, however, priming was obtained when objects and faces were overtly named. These results suggest that both face and object naming are susceptible to semantic context effects.     

Strength of visual percept generated by famous faces perceived without awareness: effects of affective valence, response latency, and visual field

Participants who were unable to detect familiarity from masked 17 ms faces (Stone and Valentine, 2004 and Stone and Valentine, in press-b) did report a vague, partial visual percept. Two experiments investigated the relative strength of the visual percept generated by famous and unfamiliar faces, using masked 17 ms exposure. Each trial presented simultaneously a famous and an unfamiliar face, one face in LVF and the other in RVF. In one task, participants responded according to which of the faces generated the stronger visual percept, and in the other task, they attempted an explicit familiarity decision. The relative strength of the visual percept of the famous face compared to the unfamiliar face was moderated by response latency and participants' attitude towards the famous person. There was also an interaction of visual field with response latency, suggesting that the right hemisphere can generate a visual percept differentiating famous from unfamiliar faces more rapidly than the left hemisphere. Participants were at chance in the explicit familiarity decision, confirming the absence of awareness of facial familiarity.     

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.     

Implicit and explicit memory without awareness

Summary Three experiments are reported which investigate the conscious status of subjects during an implicit-memory test. In all experiments the subjects either named each visually presented target item or generated each item from an anagram in a first phase of incidental learning. In a second phase, they were either given a visual word-stem completion task as an implicit-memory test or given a recognition task (Experiment 1), or a cued-recall task (Experiments 2 and 3) as explicit-memory tests. Finally, in a third phase the subjects were required to make decisions about the input status (i. e., they had to decide whether the item was present in the first phase) as well as about the output status of information (i. e., they had to decide whether the item had been completed, recognized or recalled in the second phase). A generation effect (i. e., generated items were remembered better than named items) was evident in the recognition and recall data, but only for items whose recognition or recall was accompanied by conscious recollection of their previous occurrence in the study list. Judgments about the input status were more precise, given that items had been consciously recognized or recalled rather than completed. The same pattern of findings was observed for judgments about the output status. The results are interpreted as evidence that subjects in implicit-memory tests are less aware of the fact that some of their productions are relevant to prior experiences. In addition, they are less aware of the fact that they are retrieving information from their memories. However, the same state of nonawareness may be present in explicit-memory tests, as was revealed by the performance of subjects on those items whose recognition or recall was not accompanied by conscious recollection.