Biomedical subjects

Jürgen M Kaufmann

Publications and source records attributed to Jürgen M Kaufmann.

9 recordsLinked to original sources

PubMed2006

Hemispheric asymmetries in font-specific and abstractive priming of written personal names: Evidence from event-related brain potentials.

We assessed hemispheric differences in font-specific and abstractive repetition priming for famous persons' names. Participants performed speeded familiarity judgments for foveally presented famous and unfamiliar names. Famous target names were preceded by primes (150 ms) in the left or right visual field (LVF or RVF). Primes were either the same name as the target written in the same font (font-specific priming), the same name in a different font (abstractive priming), or a different name (unprimed condition). In reaction times, LH superiority was strong for abstractive priming across fonts, but was reduced to insignificance for font-specific priming. We observed 3 different ERP modulations of priming for target names: a small font-specific posterior N200 (160-220 ms), a left temporal N250r (220-300 ms), and an N400 modulation (300-500 ms). The left temporal N250r exhibited large and abstractive priming for RVF primes, but smaller and font-specific priming for LVF primes. N400 effects were observed in all priming conditions. With respect to previous findings that N200, N250r, and N400 reflect facilitation at the levels of font-specific encoding, lexical entries for names, and semantic processing, respectively, these findings suggest that the LH superiority for name processing is particularly pronounced for the access to abstractive lexical entries for written names, a process that may be mediated by the left fusiform cortex.

Adolescent↗

PubMed2005

The Thatcher illusion seen by the brain: an event-related brain potentials study.

In "Thatcherized" faces, the eyes and mouth regions are turned upside-down. Only when presented upright they are perceived as severely distorted. Common theories explain this effect by the loss of configural information for inverted faces. We investigated neural correlates of Thatcherization using event related potentials (ERPs). Sixteen right-handed participants performed identity classifications on Thatcherized or original familiar faces, presented either for 34 ms or 200 ms at an orientation of either 0 degrees, 90 degrees or 180 degrees. For the occipito-temporal N170, we found (1) strong non-linear effects of orientation and (2) interactions between Thatcherization and orientation: Thatcherization resulted in larger N170 for upright faces, but smaller N170 for inverted faces. The novel finding of N170 effects of Thatcherization in inverted faces suggests differences in the neural encoding of Thatcherized and original inverted faces, even though Thatcherization escapes subjective perception in inverted faces.

Adolescent↗

PubMed2005

Speaker variations influence speechreading speed for dynamic faces.

We investigated the influence of task-irrelevant speaker variations on speechreading performance. In three experiments with video digitised faces presented either in dynamic, static-sequential, or static mode, participants performed speeded classifications on vowel utterances (German vowels /u/ and /i/). A Garner interference paradigm was used, in which speaker identity was task-irrelevant but could be either correlated, constant, or orthogonal to the vowel uttered. Reaction times for facial speech classifications were slowed by task-irrelevant speaker variations for dynamic stimuli. The results are discussed with reference to distributed models of face perception (Haxby et al, 2000 Trends in Cognitive Sciences 4 223-233) and the relevance of both dynamic information and speaker characteristics for speechreading.

Adult↗

PubMed2004

Expression influences the recognition of familiar faces.

Face recognition has been assumed to be independent of facial expression. We used familiar and unfamiliar faces that were morphed from a happy to an angry expression within a given identity. Participants performed speeded two-choice decisions according to whether or not a face was familiar. Consistent with earlier findings, reaction times for classifications of unfamiliar faces were independent of facial expressions. In contrast, expression clearly influenced the recognition of familiar faces. with fastest recognition for moderately happy expressions. This suggests that representations of familiar faces for recognition preserve some information about typical emotional expressions.

Adult↗

PubMed2003

Interhemispheric cooperation for face recognition but not for affective facial expressions.

Interhemispheric cooperation can be indicated by enhanced performance when stimuli are presented to both visual fields relative to one visual field alone. This "bilateral gain" is seen for words but not pseudowords in lexical decision tasks, and has been attributed to the operation of interhemispheric cell assemblies that exist only for meaningful words with acquired cortical representations. Recently, a bilateral gain has been reported for famous but not unfamiliar faces in a face recognition task [Neuropsychologia 40 (2002) 1841]. In Experiment 1 of the present paper, participants performed familiarity decisions for faces that were presented to the left (LVF), the right (RVF), or to both visual fields (BVF). An advantage for BVF relative to both LVF and RVF stimuli was seen in reaction times (RTs) to famous faces, but this bilateral advantage was absent for unfamiliar faces. In Experiment 2, participants classified the expression (happy or neutral) of unfamiliar faces. No bilateral advantage was seen for expressions, although a right hemisphere superiority was seen in terms of higher accuracy for LVF and BVF trials relative to the RVF. Recognition of famous faces (but not of facial expressions) require access to acquired memory representations that may be instantiated via cortical cell assemblies, and it is suggested that interhemispheric cooperation depends on these acquired cortical representations.

Adolescent↗

PubMed2002

Personal names and the human right hemisphere: an illusory link?

Names are thought to be represented in the brain differently from common nouns. Although this idea is supported by both theoretical and empirical arguments, the brain areas that are relevant for the recognition of personal names-and in particular the extent of right hemisphere involvement-remain controversial. We investigated the hypothesis that, unlike common nouns, personal names are represented preferentially by the right hemisphere (D. Van Lancker, 1991; D. Van Lancker et al., 1991; C. Ohnesorge & D. Van Lancker, 1999). Participants performed lexical decisions to common nouns and pseudowords (Experiment 1) or familiarity decisions to personal names (Experiment 2), which were presented briefly to the left or right visual fields. Asymmetries were small or absent for both pseudowords and unfamiliar names. For familiar names, both reaction times and error rates revealed strong advantages for the right visual field/left hemisphere (RVF/LH), which were comparable to the asymmetries for nouns. Familiar personal names may be represented by brain systems that differ from those representing common nouns, but current evidence does not suggest a distinct contribution of the right hemisphere to these brain systems.

Adult↗

PubMed2002

Human brain potential correlates of repetition priming in face and name recognition.

We investigated repetition priming in the recognition of famous people by recording event-related brain potentials (ERPs) and reaction times (RTs). Participants performed speeded two-choice responses depending on whether or not a stimulus showed a famous person. In Experiment 1, a facilitation was found in RTs to famous (but not to unfamiliar) faces when primed by the same face shown in an earlier priming phase of the experiment. In ERPs, an influence of repetition priming was observed neither for the N170 nor for a temporal N250 component which in previous studies had been shown to be sensitive to immediate face repetitions. ERPs to primed unfamiliar faces were more negative over right occipitotemporal areas than those to unprimed faces, but this effect was specific for repetitions of the same image, consistent with recent findings. In contrast, ERPs to primed familiar faces were more positive than those to unprimed faces at parietal sites from 500-600 ms after face onset, and these priming effects were comparable regardless of whether the same or a different image of the celebrity had served as prime. In Experiment 2, similar results were found for name recognition-a facilitation in RTs to primed familiar but not unfamiliar names, and a parietal positivity to primed names around 500-600 ms. ERP repetition effects showed comparable topographies for faces and names, consistent with the idea of a common underlying source. With reference to current models of face recognition, we suggest that these ERP repetition effects for familiar stimuli reflect a change in post-perceptual representations for people, rather than a neural correlate of recognition at a perceptual level.

Adolescent↗

PubMed2002

Famous personal names and the right hemisphere: the link keeps missing.

In this reply to the comment by VanLancker and Ohnesorge (2002), we present the case that current evidence supports the role of left hemisphere in the recognition of famous personal names. We argue that this conclusion is in line not only with the results of Schweinberger, Landgrebe, Mohr, and Kaufmann (2002), but also with the evidence from methods other than divided visual field studies (e.g., PET and ERP studies). We show that our view is also supported by a new set of experiments that address a major concern raised by VanLancker and Ohnesorge in their comment and discuss why the evidence they present does not provide conclusive support to their right hemisphere hypothesis. One of the several possible reasons for this failure is that famous name stimuli may be less suitable than personally familiar stimuli to elicit personally relevant, affective aspects of recognition.

Adult↗

PubMed2002

Event-related brain potential evidence for a response of inferior temporal cortex to familiar face repetitions.

We investigated immediate repetition effects in the recognition of famous faces by recording event-related brain potentials (ERPs) and reaction times (RTs). Participants recognized celebrities' faces that were preceded by either the same picture, a different picture of the same celebrity, or a different famous face. Face repetition caused two distinct ERP modulations. Repetitions elicited a strong modulation of an N250 component ( approximately 200-300 ms) over inferior temporal regions. The N250 modulation showed a degree of image specificity in that it was still significant for repetitions across different pictures, though reduced in amplitude. ERPs to repeated faces were also more positive than those to unprimed faces at parietal sites from 400 to 600 ms, but these later effects were largely independent of whether the same or a different image of the celebrity had served as prime. Finally, no influence of repetition was observed for the N170 component. Dipole source modelling suggested that the N250 repetition effect (N250r) may originate from the fusiform gyrus. In contrast, source localisation of the N170 implicated a significantly more posterior location, corresponding to a lateral occipitotemporal source outside the fusiform gyrus.

Adolescent↗