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Biomedical subjects

A W Ellis

Publications and source records attributed to A W Ellis.

At least 19 recordsLinked to original sources
PubMed1992

Cognitive mechanisms of face processing.

Evidence from natural and induced errors of face recognition, from the effects of different cues on resolving errors, and from the latencies to make different decisions about seen faces, all suggest that familiar face recognition involves a fixed, invariant sequence of stages. To recognize a familiar face, a perceptual description of a seen face must first activate a long-standing representation of the appearance of the face of the familiar person. 'Semantic' knowledge about such things as the person's occupation and personality are accessed next, followed, in the final stage, by the name. Certain factors affect the ease of familiar face recognition. Faces seen in the recent past are recognized more readily (repetition priming), as are distinctive faces, and faces preceded by those of related individuals (associative priming). Our knowledge of these phenomena is reviewed for the light it can shed upon the mechanisms of face recognition. Four aspects of face recognition--graded similarity effects and part-to-whole completion in repetition priming, prototype extraction with simultaneous retention of information about individual exemplars, and distinctiveness effects in classification and identification--are proposed as being compatible with distributed memory accounts of cognitive representations.

Association Learning↗
PubMed1992

Repetition priming follows spontaneous but not prompted recognition of familiar faces.

Reaction times to make a familiarity decision to the faces of famous people were measured after recognition of the faces in a pre-training phase had occurred spontaneously or following prompting with a name or other cue. At test, reaction times to familiar faces that had been recognized spontaneously in the pre-training phase were significantly facilitated relative to an unprimed comparison condition. Reaction times to familiar faces recognized only after prompting in the pre-training phase were not significantly facilitated. This was demonstrated both when a name prompt was used (Experiments 1 and 3) and when subjects were cued with brief semantic information (Experiment 2). Repetition priming was not found to depend on prior spontaneous recognition per se. In Experiment 3, spontaneously recognizing a familiar face did not prime subsequent familiarity judgements when the same face had only been identified following prompting on a prior encounter. In Experiment 4, recognition memory for faces recognized after cueing was found to be over 90% accurate. This indicates that prompted recognition does not yield repetition priming, even though subjects can remember the faces. A fusion of "face recognition unit" and "episodic record" accounts of the repetition priming effect may be more useful than either theory alone in explaining these results.

Cues↗
PubMed1992

Phonological priming of lexical retrieval in speech production.

We report a series of three experiments exploring phonological priming effects in speech production. In all cases, subjects repeated aloud auditorily presented primes and then named picture targets. Experiment 1 showed that targets were named faster when prime and target shared phonemes but only when these occupied the same word or syllabic positions. Experiment 2 showed that the degree of facilitation was unaffected by the lexicality of the prime or whether shared phonemes occurred early or late in the syllable. Experiment 3 examined the effect of the lexicality of the prime at different intervals between response and prime in an attempt to tease apart contributions to the effect from automatic and strategic processes. The results are considered in relation to current accounts of lexical retrieval.

Analysis of Variance↗
PubMed1992

Age of acquisition, not word frequency, affects object naming, not object recognition.

Word frequency is widely believed to affect object naming speed, despite several studies in which it has been reported that frequency effects may be redundant upon age of acquisition. We report, first, a reanalysis of data from the study by Oldfield and Wingfield (1965), which is standardly cited as evidence for a word frequency effect in object naming; then we report two new experiments. The reanalysis of Oldfield and Wingfield shows that age of acquisition is the major determinant of naming speed, and that frequency plays no independent role when its correlation with other variables is taken into account. In Experiment 1, age of acquisition and phoneme length proved to be the primary determinants of object naming speed. Frequency, prototypicality, and imageability had no independent effect. In Experiment 2, subjects classified objects into two semantic categories (natural or man-made). Prototypicality and semantic category were the only variables to have a significant effect on reaction time, with no effect of age of acquisition, frequency, imageability, or word length. We conclude that age of acquisition, not word frequency, affects the retrieval and/or execution of object names, not the process of object recognition. The locus of this effect is discussed, along with the possibility that words learned in early childhood may be more resistant to the effects of brain injury in at least some adult aphasics than words learned somewhat later.

Adult↗
PubMed1991

Understanding covert recognition.

An implementation of Bruce and Young's (1986) functional model of face recognition is used to examine patterns of covert face recognition previously reported in a prosopagnosic patient, PH. Although PH is unable to recognize overly the faces of people known to him, he shows normal patterns of face processing when tested indirectly. A simple manipulation of one set of connections in the implemented model induces behaviour consistent with patterns of results from PH obtained in semantic priming and interference tasks. We compare this account with previous explanations of covert recognition and demonstrate that the implemented model provides the most natural and parsimonious account available. Two further patients are discussed who show deficits in person perception. The first (MS) is prosopagnosic but shows no covert recognition. The second (ME) is not prosopagnosic, but cannot access semantic information relating to familiar people. The model provides an account of recognition impairments which is sufficiently general also to be useful in describing these patients.

Adult↗
PubMed1991

Analysis of the spontaneous writing errors of normal and aphasic writers.

Samples of spontaneous writing were collected from 150 normal subjects, 13 Broca's aphasics, 23 Wernicke's aphasics and 14 conduction aphasics. The errors obtained were classified using a system derived from investigations of slips of the pen in normal subjects. All three aphasic groups made a higher proportion of word-level errors than did the normal writers. Word-level errors tended to be selection errors (substitutions, blends, neologisms, and omissions) rather than movement errors (anticipations, perseverations and reversals). Conduction aphasics showed proportionately more letter movement and fewer letter selection errors than normal writers while Wernicke's and Broca's aphasics showed similar proportions. Graphic and phonetic similarity was no more important a determinant of letter errors in aphasics than in normals. The span of movement errors was particularly restricted in the Broca's and conduction aphasics. Asking patients to write connected text yields insight into the nature of the underlying disorder that could not be obtained from studying the writing of single words.

Agraphia↗
PubMed1991

Routes through the face recognition system.

Two experiments are reported which seek to examine the proposition first put forward by Hay and Young (1982), that recognition of a known person after seeing his or her face proceeds through a series of sequentially organized stages. In both experiments subjects were shown a selection of famous and unfamiliar faces and required to state whether each face was familiar. They were then asked to recall semantic information and the person's name. Of all the possible response types, only some are predicted by models derived from Hay and Young (1982), and only these responses were observed in Experiment 1. In order to give as complete an account as possible of the slips and errors made by subjects, they were interrogated some days after completing the testing phase in Experiment 2. As in the first experiment, the results supported the view that distinct but successive stages are involved in everyday face recognition. The method developed here provides an extension of the "dairy" type of study of everyday recognition errors into laboratory conditions, which confirms the findings of studies of everyday errors and provides strong support for sequential models.

Adult↗
PubMed1990

Repetition priming and face processing: priming occurs within the system that responds to the identity of a face.

A familiar stimulus that has recently been recognized will be recognized a second time more quickly and more accurately than if it had not been primed by the earlier encounter. This is the phenomenon of "repetition priming". Four experiments on repetition priming of face recognition suggest that repetition priming is a consequence of changes within the system that responds to the familiarity of a stimulus. In Experiment 1, classifying familiar faces by occupation facilitated subsequent responses to the same faces in a familiarity decision task (Is this face familiar or unfamiliar?) but not in an expression decision task (Is this face smiling or unsmiling?) or a sex decision task (Is this face male or female?). In Experiment 2, familiar faces showed repetition priming in a familiarity decision task, regardless of whether a familiarity judgment or an expression judgment had been required when the faces were first encountered. Expression decisions to familiar faces again failed to show repetition priming. In Experiment 3, familiar faces showed repetition priming in a familiarity decision task, regardless of whether a familiarity judgment or a sex judgment had been asked for when the faces were first encountered. Sex decisions to familiar faces again failed to show repetition priming. In Experiment 4, familiarity decisions continued to show repetition priming when a brief presentation time with encouragement to respond while the face was displayed reduced response latencies to speeds comparable to those for sex and expression judgments in Experiments 1 to 3. The results are problematic for theories that propose that repetition priming is mediated by episodic records of previous acts of stimulus encoding.

Adult↗
PubMed1990

Repetition priming from incomplete faces: evidence for part to whole completion.

Two experiments are reported in which subjects' reaction times to make familiarity decisions to the faces of famous people were compared for faces primed by previously seeing (1) the internal features of the same face, (2) the external features of the same face, or (3) a complete version of the same face. Reaction times to faces primed by the internal features, the external features or a complete face were significantly facilitated relative to an 'unprimed' comparison condition, and did not differ one from another. Viewing part of a familiar face on a previous occasion was therefore found to be as effective at priming recognition as seeing a whole face. This finding was demonstrated in Expt 1 for priming from the repetition of stimuli derived from an identical photograph of the same famous person, and in Expt 2 for priming from stimuli derived from a different photograph of the same familiar face. 'Distributed processing' accounts of repetition priming may be more useful than accounts based entirely on episodic records in explaining these results.

Adult↗
PubMed1989

Face processing and name retrieval in an anomic aphasic: names are stored separately from semantic information about familiar people.

Recent models of face recognition have proposed that the names of familiar people are accessed from a lexical memory store that is distinct from the semantic memory store that holds information about such things as a familiar person's occupation and personality. Names are nevertheless retrieved via the semantic system. If such models are correct, then it should be possible for a patient to have full access to semantic information about familiar people while being unable to name many of them. We report this pattern in an anomic aphasic patient, EST, whose inability to recall the names of familiar people occurred in the context of a general word-finding problem. EST showed a preserved ability to access semantic information from familiar faces, voices, and spoken and written names and to process facial expressions, but he was unable to name many familiar faces. These findings are compatible with current models of face processing and challenge models which propose that names are stored alongside semantic information in a general-purpose long-term memory store.

Anomia↗
PubMed1989

Loss of memory for people following temporal lobe damage.

A 40-yr-old woman, K.S., is reported, who shows a severe loss of memory for people following a history of epilepsy and right anterior temporal lobectomy. Despite this memory problem, K.S. is not clinically amnesic, has a Memory Quotient of 122 on the Wechsler Memory Scale in line with her IQ of 119, and performs well on conventional tests of recognition and recall. She does not have a generalized semantic memory deficit for living things, but her deficit extends beyond people to include famous animals, buildings and product names. Autobiographical memory is good, except where memory for people is concerned. The nature of the memory store that is impaired in K.S. is discussed, as are the implications of her case for theories of the organization of long-term memory.

Adult↗
PubMed1988

Modes of word recognition in the left and right cerebral hemispheres.

Four experiments are reported examining the effects of word length on recognition performance in the left and right visual hemifields (LVF, RVF). In Experiments 1 and 2 length affected lexical decision latencies to words presented in the LVF but not to words presented in the RVF. This result was found for both concrete and abstract nouns. Changing from a normal horizontal format to the use of unconventionally "stepped" words, however, produced length effects for words in both visual hemifields (Experiment 3). The Length x VHF interaction was found once again in Experiment 4 where subjects classified words as either concrete or abstract. A model proposing two modes of visual processing of letter strings is presented to account for these findings. Mode A operates independent of string length and is seen only in left hemisphere analysis of familiar words. Mode B is length dependent: it is the only mode possessed by the right hemisphere but is displayed by the left hemisphere to nonwords and to words in abnormal formats.

Cerebral Cortex↗
PubMed1987

More things in heaven and earth than are dreamt of in the initial letter acuity hypothesis.

Schwartz, Montagner, and Kirsner (1987 Brain and Language, 31, 301-307) claim that length X visual hemifield interactions for recognition of horizontal words reflect acuity differences for the initial letters of short and long words rather than different methods of lexical access for words presented in the LVF and in the RVF. They argue that Young and Ellis did not satisfactorily eliminate this possibility because they (Young & Ellis, 1985, Brain and Language, 24, 326-358, Experiment 3) allowed the use of sophisticated guessing strategies. We demonstrate that the presentation conditions of the Schwartz et al. (1987) experiment are different from those of our (Young & Ellis, 1985) experiments in potentially important ways, and that the acuity gradient explanation proposed by Schwartz et al. to account for word length X visual hemifield interactions is inadequate in terms of both the existing literature and a reanalysis of data from our own (Young & Ellis, 1985) Experiments 1 and 3.

Dominance, Cerebral↗
PubMed1986

Face-name interference.

Interference effects between the processing of simultaneously presented photographs of faces of familiar people and printed names of familiar people were investigated. Printed names interfered with identifying faces, whereas faces did not interfere with saying printed names (Experiments 1 and 3). In contrast, faces interfered more with name categorization than names interfered with face categorization (Experiments 2 and 4). Despite a priori reasons as to why faces might be thought to possess functional properties different from those of other visual objects, the observed effects are comparable to those found in object-word interference studies, with photographs of faces behaving like pictures of objects and printed people's names behaving like printed names of objects. In face naming tasks, the presence of related names produced more interference than did the presence of unrelated names (Experiment 1). This effect was examined in greater detail in Experiment 3, where we found that the effect arises when the face and the name belong to people of similar appearance. An effect of common category membership was not found in Experiment 3. Experiment 5, however, showed that names of people highly associated with the person whose face is presented also produce more interference than do names of unrelated people.

Association↗