Benjamin Dering

Unconscious effects of language-specific terminology on preattentive color perception.

It is now established that native language affects ones perception of the world. However, it is unknown whether this effect is merely driven by conscious, language-based evaluation of the environment or whether it reflects fundamental differences in perceptual processing between individuals speaking different languages. Using brain potentials, we demonstrate that the existence in Greek of 2 color terms—ghalazio and ble—distinguishing light and dark blue leads to greater and faster perceptual discrimination of these colors in native speakers of Greek than in native speakers of English. The visual mismatch negativity, an index of automatic and preattentive change detection, was similar for blue and green deviant stimuli during a color oddball detection task in English participants, but it was significantly larger for blue than green deviant stimuli in native speakers of Greek. These findings establish an implicit effect of language-specific terminology on human color perception.

Brain potentials reveal semantic priming in both the ‘active’ and the ‘non-attended’ language of early bilinguals

A key question in the study of bilingual functioning is whether both the languages known are active at all times or whether one language can be selectively inactivated when bilingual individuals are tuned to the other language. Psycholinguistic and neuroscientific investigations have provided inconsistent data regarding the level of semantic activation of the two languages, even in the case of highly proficient bilinguals. In the present study, highly proficient, early Welsh/English bilinguals were presented with words in both their languages and were required to make word length decisions on words in one language while disregarding words in the other. Participants were not explicitly told about the organization of the word stream in pairs manipulating (a) semantic relatedness, (b) language of the prime and (c) language of the target in a fully counterbalanced two-by-two-by-two design. We observed significant semantic priming for both English and Welsh target words, irrespective of the active language, and independent of performance in the low-level letter counting task. We conclude that accessing the meaning of a written word is automatic in the two languages even when fluent bilingual adults are instructed to disregard words in one of their languages.

Perceptual shift in bilingualism: Brain potentials reveal plasticity in pre-attentive colour perception

The validity of the linguistic relativity principle continues to stimulate vigorous debate and research. The debate has recently shifted from the behavioural investigation arena to a more biologically grounded field, in which tangible physiological evidence for language effects on perception can be obtained. Using brain potentials in a colour oddball detection task with Greek and English speakers, a recent study suggests that language effects may exist at early stages of perceptual integration [Thierry, G., Athanasopoulos, P., Wiggett, A., Dering, B., & Kuipers, J. (2009). Unconscious effects of language-specific terminology on pre-attentive colour perception. Proceedings of the National Academy of Sciences, 106, 4567-4570]. In this paper, we test whether in Greek speakers exposure to a new cultural environment (UK) with contrasting colour terminology from their native language affects early perceptual processing as indexed by an electrophysiological correlate of visual detection of colour luminance. We also report semantic mapping of native colour terms and colour similarity judgements. Results reveal convergence of linguistic descriptions, cognitive processing, and early perception of colour in bilinguals. This result demonstrates for the first time substantial plasticity in early, pre-attentive colour perception and has important implications for the mechanisms that are involved in perceptual changes during the processes of language learning and acculturation.

Behavioral and ERP evidence for amodal sluggish attentional shifting in developmental dyslexia

The goal of this study was to examine the claim that amodal deficits in attentional shifting may be the source of reading acquisition disorders in phonological developmental dyslexia (sluggish attentional shifting, SAS, theory, Hari & Renvall, 2001). We investigated automatic attentional shifting in the auditory and visual modalities in 13 dyslexic young adults with a phonological awareness deficit and 13 control participants, matched for cognitive abilities, using both behavioral and ERP measures. We tested automatic attentional shifting using a stream segregation task (perception of rapid succession of visual and auditory stimuli as one or two streams). Results of Experiment 1(behavioral) suggested that in order to process two successive stimuli separately dyslexic participants required a significantly longer inter-stimulus interval than controls regardless of sensory modality. In Experiment 2 (ERPs), the same participants were tested by means of an auditory and a visual oddball tasks involving variations in the tempo of the same alternating stimuli as Experiment 1. P3b amplitudes elicited by deviant tempos were differently modulated between groups, supporting predictions made on the basis of observations in Experiment 1. Overall, these results support the hypothesis that SAS in dyslexic participants might be responsible for their atypical perception of rapid sequential stimulus sequences in both the auditory and the visual modalities. Furthermore, these results bring new evidence supporting the link between amodal SAS and the phonological impairment in developmental dyslexia.

Face-sensitive processes one hundred milliseconds after picture onset.

The human face is the most studied object category in visual neuroscience. In a quest for markers of face processing, event-related potential (ERP) studies have debated whether two peaks of activity – P1 and N170 – are category-selective. Whilst most studies have used photographs of unaltered images of faces, others have used cropped faces in an attempt to reduce the influence of features surrounding the “face–object” sensu stricto. However, results from studies comparing cropped faces with unaltered objects from other categories are inconsistent with results from studies comparing whole faces and objects. Here, we recorded ERPs elicited by full front views of faces and cars, either unaltered or cropped. We found that cropping artificially enhanced the N170 whereas it did not significantly modulate P1. In a second experiment, we compared faces and butterflies, either unaltered or cropped, matched for size and luminance across conditions, and within a narrow contrast bracket. Results of Experiment 2 replicated the main findings of Experiment 1. We then used face–car morphs in a third experiment to manipulate the perceived face-likeness of stimuli (100% face, 70% face and 30% car, 30% face and 70% car, or 100% car) and the N170 failed to differentiate between faces and cars. Critically, in all three experiments, P1 amplitude was modulated in a face-sensitive fashion independent of cropping or morphing. Therefore, P1 is a reliable event sensitive to face processing as early as 100u2009ms after picture onset.

Sensitivity of the autonomic nervous system to visual and auditory affect across social and non-social domains in williams syndrome.

Although individuals with Williams syndrome (WS) typically demonstrate an increased appetitive social drive, their social profile is characterized by dissociations, including socially fearless behavior coupled with anxiousness, and distinct patterns of “peaks and valleys” of ability. The aim of this study was to compare the processing of social and non-social visually and aurally presented affective stimuli, at the levels of behavior and autonomic nervous system (ANS) responsivity, in individuals with WS contrasted with a typically developing (TD) group, with the view of elucidating the highly sociable and emotionally sensitive predisposition noted in WS. Behavioral findings supported previous studies of enhanced competence in processing social over non-social stimuli by individuals with WS; however, the patterns of ANS functioning underlying the behavioral performance revealed a surprising profile previously undocumented in WS. Specifically, increased heart rate (HR) reactivity, and a failure for electrodermal activity to habituate were found in individuals with WS contrasted with the TD group, predominantly in response to visual social affective stimuli. Within the auditory domain, greater arousal linked to variation in heart beat period was observed in relation to music stimuli in individuals with WS. Taken together, the findings suggest that the pattern of ANS response in WS is more complex than previously noted, with increased arousal to face and music stimuli potentially underpinning the heightened behavioral emotionality to such stimuli. The lack of habituation may underlie the increased affiliation and attraction to faces characterizing individuals with WS. Future research directions are suggested.

Is the N170 peak of visual event-related brain potentials car-selective?

The N170 is a peak of event-related brain potentials commonly acknowledged to be larger in amplitude for face stimuli compared with any other visual object. Recently, the face selectivity of the N170 has been challenged based on the observation of similar N170 amplitude to faces and cars presented full front. Here, we measured the N170 elicited by the same stimulus categories using a one-back memory and categorization tasks. We found that N170 mean amplitude was significantly larger for cars than faces at electrode sites considered ‘optimal’ for measuring N170 face selectivity in the absence of task effects. Furthermore, we found evidence for category selectivity and task dependence in the P1 range. These results support the idea that N170 face selectivity is formally questionable.

Seeing objects through the language glass

Recent streams of research support the Whorfian hypothesis according to which language affects ones perception of the world. However, studies of object categorization in different languages have heavily relied on behavioral measures that are fuzzy and inconsistent. Here, we provide the first electrophysiological evidence for unconscious effects of language terminology on object perception. Whereas English has two words for cup and mug, Spanish labels those two objects with the word “taza.” We tested native speakers of Spanish and English in an object detection task using a visual oddball paradigm, while measuring event-related brain potentials. The early deviant-related negativity elicited by deviant stimuli was greater in English than in Spanish participants. This effect, which relates to the existence of two labels in English versus one in Spanish, substantiates the neurophysiological evidence that language-specific terminology affects object categorization.

Category-sensitivity in the N170 range: A question of topography and inversion, not one of amplitude

Event-related potential studies have identified the N170 as the key neurophysiological marker of human face processing. This functional association relies on the observation of a larger N170 amplitude to faces than items from all other visual object categories. However, N170 amplitude is modulated by stimulus variations like viewpoint, size and symmetry, and studies comparing similarly sized and symmetric full-front faces and other objects have failed to find amplitude differences. Here we tested whether the effect of inversion - an increase in N170 amplitude seen for faces presented upside down - is similarly observed for full-front views of cars. Participants discriminated pictures of faces and cars, which were presented upright and inverted, and either in full-front view or varying in size, orientation and viewpoint. For upright stimuli, the N170 was stronger for faces than cars at some electrode sites, but of comparable amplitude at others, as shown by topographical differences. The N170 for inverted faces and cars was delayed, with a stronger delay for faces than cars. Inversion increased N170 amplitude for faces, while modulations for full-front view cars were non-significant or N170 amplitude was reduced. These results further limit the widely acknowledged principle of an association between N170 and visual object categorization. Potential face-sensitivity in the N170 range may therefore rely on topographic differences and effects of inversion, rather than amplitude differences.

Effects of Speed of Word Processing on Semantic Access: The Case of Bilingualism.

Bilingual speakers generally manifest slower word recognition than monolinguals. We investigated the consequences of the word processing speed on semantic access in bilinguals. The paradigm involved a stream of English words and pseudowords presented in succession at a constant rate. English-Welsh bilinguals and English monolinguals were asked to count the number of letters in pseudowords and actively disregard words. They were not explicitly told that pairs of words in immediate succession were embedded and could either be semantically related or not. We expected that slower word processing in bilinguals would result in semantic access indexed by semantic priming. As expected, bilinguals showed significant semantic priming, indexed by an N400 modulation, whilst monolinguals did not. Moreover, bilinguals were slower in performing the task. The results suggest that bilinguals cannot discriminate between pseudowords and words without accessing semantic information whereas monolinguals can dismiss English words on the basis of subsemantic information.