OS_14. Auditory perception and Multisensory integration

Saturday, October 01st,   2011 [08:30 - 10:30]

TALKS

OS_14.1 - Auditory spatial negative priming: Are responses to irrelevant sound locations suppressed?

Mayr, S. , Möller, M. & Buchner, A.

Heinrich-Heine-University Düsseldorf

The visuospatial negative priming effect-that is, the slowed-down responding to a previously ignored location-is partly due to response inhibition associated with the previously ignored location. We tested whether response inhibition underlies spatial negative priming in the auditory modality as well. 78 participants localized a target sound while ignoring a simultaneous distractor sound at another location. Sounds were presented from one of 8 locations arranged in a semicircle around the participant. Pairs of adjacent locations were associated with the same response. In location-repeated trials, the probe target sound was played from the same location as the previously ignored prime sound. In response-repeated trials, prime distractor and probe target were played from different locations but were associated with the same response. In control trials, prime distractor and probe target neither shared location nor response. A response inhibition account predicts slowed-down responding when the response associated with the prime distractor has to be executed in the probe. There was no evidence of response inhibition in audition. Instead, negative priming depended on whether the sound at the repeatedly occupied location changed identity between prime and probe. This latter result replicates earlier findings and supports the feature-mismatch hypothesis.

OS_14.2 - Vision and audition in space and time: Crossmodal interference in switching stimulus modalities

Lukas, S. ^{1, 2} , Philipp, A. M. ² & Koch, I. ²

1 General Psychology, Ulm University, Ulm, Germany
2 Cognitive and Experimental Psychology, RWTH Aachen, Aachen, Germany

Often, a visual stimulus can be processed faster than an accompanying stimulus in another modality. This effect is called visual dominance. The modality appropriateness hypothesis (cf. Freides, 1974) explains this effect in stating that stimuli in different modalities are differently effective processed depending on the dimension in which they are situated. For example, perception and processing of visual stimuli work best in the dimension of space, whereas in the dimension of time auditory stimuli are favored. In earlier studies, we already showed a clear benefit for visual stimuli in a modality-switch situation. In these studies subjects were required to make a spatial decision of the stimulus in the relevant modality. We found that for visual stimuli, RT and interference effects were smaller than for auditory stimuli. In the present study, we examined the assumption that this benefit should be reduced or even reversed in a timely task. Subjects were now required to fulfill a timely task. We found indeed that RT did not differ anymore in this setting. The interference effect was even reversed. We discuss our findings with respect of the modality-appropriateness hypothesis, as well as the hypothesis of directed attention (e.g., Posner, Nissen, & Klein, 1976).

OS_14.3 - Evidence for a dual vs single origin of the Mismatch Negativity (MMN)

Colin, C. ¹ , Hoonhorst, I. ¹ , Markessis, E. ² , Collet, G. ^{1, 3} , Pablos Martin, X. ¹ & Deltenre, P. . ¹

1 Free University of Brussels (ULB), Belgium
2 Institut Libre Marie Haps, Brussels, Belgium
3 FNRS Belgium

This study was designed to test separately the effect of the featured/featureless nature of deviant stimuli and that of temporal distance between sound and deviance onsets on the Mismatch Negativity (MMN) as well as to look for discrepancies between behavioral discrimination performances and MMN amplitude when deviants are featureless. Ten healthy adults were submitted to stimuli that were contrasted by the presence or absence of a frequency sweep with an onset positioned early or late within the sound. Discrimination performances were collected after the electrophysiological sessions. MMNs were much larger for featured than for featureless deviants. The temporal distance between sound and deviance onset affected featureless deviants strongly, abolishing the MMN when deviance occurred later in the stimulus. Behavioral data were at ceiling levels for all conditions, contrasting with the absence of MMN in the featureless / late onset condition. We propose that two mechanisms contribute to the MMN evoked by featured deviants: the memory comparison process and the adaptation/fresh-afferent one, the former being more sensitive to deviance onset within the Temporal Window of Integration than the latter. These results suggest that the two putative mechanisms of MMN elicitation are not mutually exclusive and can combine to yield composite MMNs.

OS_14.4 - Impulsiveness dissociates in early deaf individuals: modality specific reactivity enhancement and amodal, poor sensitivity in temporal discrimination

Heimler, B. ¹ & Pavani, F. ^{1, 2}

1 Center for Mind/Brain Sciences, University of Trento, Italy
2 Department of Cognitive Science and Education, University of Trento, Italy

Reactivity enhancement has been repeatedly observed in deaf compared to hearing individuals through visual simple detection tasks, but it remains unknown whether these effects extend to other intact sensory modalities. Deaf also proved worse than hearing individuals on tactile temporal discrimination, but this ability has never been investigated in vision. It is thus unclear whether these differences are modality specific or amodal. Eight early deaf (loss > 70dB) and twelve hearing participants performed a simple detection or a temporal discrimination task. Stimuli were either tactile or visual, and they occurred at central or peripheral locations (vision: 1° and 32°; touch: forefinger, forearm, neck). Simple detection revealed a clear modality specific effect in deaf individuals: reactivity enhancement emerged selectively for vision, with no anticipation responses and regardless of stimulus eccentricity. By contrast, temporal discrimination revealed an amodal effect in deaf individuals, with poor sensitivity for both modalities and a clear speed-accuracy trade-off. The modality specific effect excludes a role for motivational and motor preparation factors in enhanced reactivity to visual events, suggesting instead a role of perceptual and attentional processes. The amodal finding reveals, however, that impulsiveness may indeed characterise deaf performance, particularly when a difficult perceptual discrimination is required.

OS_14.5 - Audio-Visual integration in children with Cochlear implant

Leybaert, J. ¹ , Berthommier, F. ² & Huyse, A. ¹

1 Université libre de Bruxelles
2 Gipsa-Lab

The study aimed to test whether audio-visual speech integration in cochlear-implanted (CI) children and in normally hearing children exposed to degraded auditory stimuli is impacted by the degradation of the visual speech information. A group of 31 children with CI and a group of 31 normally hearing children (who received spectrally reduced speech), matched for chronological age, performed a syllable identification task where stimuli were presented randomly in auditory only (AO), visual only (VO) and audiovisual (AV) (congruent and incongruent McGurk stimuli). The visual speech cue was normal in half of the experiment, and degraded in the other half. Results show that performances in VO and in congruent AV modalities were decreased in visual reduction, showing that our technique was efficient at degrading lip- reading. Visual reduction also led to a major increase of auditory-based responses to McGurk stimuli in hearing as well as in deaf children, and this increase of auditory responses was larger in children who were proficient in the use of their implant. The increase of the weight of audition, including in cochlear-implanted children whose perception is generally dominated by vision, suggests that the natural imbalance in favour of vision is not immutable.

OS_14.6 - To see and hear a word, we inefficiently combine features but efficiently combine streams

Dubois, M. ^{1, 2} , Poeppel, D. ² & Pelli, D. G. ²

1 Laboratoire Cognition, Langage et Développement, Université Libre de Bruxelles, Brussels, Belgium
2 Psychology and Neural Science, New York University, New York, USA

To recognize an object, we detect and bind the features it is made of. We also merge information across the senses into a coherent percept of our external environment. In general, how well do we combine information from several sources, be they features, cues, or sensory modalities? Building on the classic efficiency approach, here we introduce a “relative efficiency” paradigm to assess binding. We measure the energy threshold as a function of object extent (a word) or for a combination as opposed to each component alone (audio and visual). Efficient binding has a fixed energy threshold, independent of length or distribution among modalities. Inefficient binding requires more energy as length or number of modalities increases. Our results reveal an amazing dichotomy. Energy is integrated inefficiently within each modality: Observers need more energy to recognize longer words, whether seen or heard. However, text and speech summate perfectly: Observers require the same overall energy, irrespective of its distribution across eye and ear. Thus, to see and hear a word, we inefficiently combine features but efficiently combine streams.