Biomedical subjects

Seana Coulson

Publications and source records attributed to Seana Coulson.

9 recordsLinked to original sources

PubMed2007

How iconic gestures enhance communication: an ERP study.

EEG was recorded as adults watched short segments of spontaneous discourse in which the speaker's gestures and utterances contained complementary information. Videos were followed by one of four types of picture probes: cross-modal related probes were congruent with both speech and gestures; speech-only related probes were congruent with information in the speech, but not the gesture; and two sorts of unrelated probes were created by pairing each related probe with a different discourse prime. Event-related potentials (ERPs) elicited by picture probes were measured within the time windows of the N300 (250-350 ms post-stimulus) and N400 (350-550 ms post-stimulus). Cross-modal related probes elicited smaller N300 and N400 than speech-only related ones, indicating that pictures were easier to interpret when they corresponded with gestures. N300 and N400 effects were not due to differences in the visual complexity of each probe type, since the same cross-modal and speech-only picture probes elicited N300 and N400 with similar amplitudes when they appeared as unrelated items. These findings extend previous research on gesture comprehension by revealing how iconic co-speech gestures modulate conceptualization, enabling listeners to better represent visuo-spatial aspects of the speaker's meaning.

Adult↗

PubMed2005

Hemispheric asymmetry and pun comprehension: when cowboys have sore calves.

Event-related potentials (ERPs) were recorded as healthy participants listened to puns such as "During branding, cowboys have sore calves." To assess hemispheric differences in pun comprehension, visually presented probes that were either highly related (COW), moderately related (LEG), or unrelated, were presented in either the left or right visual half field (LVF/RVF). The sensitivity of each hemisphere to the different meanings evoked by the pun was assessed by ERP relatedness effects with presentation to the LVF and the RVF. In Experiment 1, the inter-stimulus interval between the pun and the onset of the visual probe was 0 ms; in Experiment 2, this value was 500 ms. In Experiment 1, both highly and moderately related probes elicited similar priming effects with RVF presentation. Relative to their unrelated counterparts, related probes elicited less negative ERPs in the N400 interval (300-600 ms post-onset), and more positive ERPs 600-900 ms post-onset, suggesting both meanings of the pun were equally active in the left hemisphere. LVF presentation yielded similar priming effects (less negative N400 and a larger positivity thereafter) for the highly related probes, but no effects for moderately related probes. In Experiment 2, similar N400 priming effects were observed for highly and moderately related probes presented to both visual fields. Compared to unrelated probes 600-900 ms post-onset, related probes elicited a centro-parietal positivity with RVF presentation, but a fronto-polar positivity with LVF presentation. Results suggest that initially, the different meanings evoked by a pun are both active in the left hemisphere, but only the most highly related meaning is active in the right hemisphere. By 500 ms, both meanings are active in both hemispheres.

Adolescent↗

PubMed2005

Hemispheric asymmetries and joke comprehension.

Joke comprehension deficits in patients with right hemisphere (RH) damage raise the question of the role of the intact RH in understanding jokes. One suggestion is that semantic, or meaning, activations are different in the RH and LH, and RH meanings are particularly important for joke comprehension. To assess whether hypothesized differences in semantic activation in the two hemispheres were relevant to joke comprehension, we recorded event-related brain potentials (ERPs) as healthy adults read laterally presented "punch words" to one-line jokes and nonjoke controls. Jokes presented to the RVF/LH elicited larger amplitude N400 than the nonjoke endings; when presented to the LVF/RH, the joke and nonjoke endings elicited N400s of equal amplitude. This finding suggests that semantic activations in the two hemispheres do differ, with RH semantic activation facilitating joke comprehension.

Adult↗

PubMed2005

Right hemisphere sensitivity to word- and sentence-level context: evidence from event-related brain potentials.

Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing.

Adult↗

PubMed2005

Meaningful gestures: electrophysiological indices of iconic gesture comprehension.

To assess semantic processing of iconic gestures, EEG (29 scalp sites) was recorded as adults watched cartoon segments paired with soundless videos of congruous and incongruous gestures followed by probe words. Event-related potentials time-locked to the onset of gestures and probe words were measured in two experiments. In Experiment 1, participants judged the congruency between gestures and cartoons. Gestures elicited an N400-like component (gesture N450) that was larger for incongruent than congruent items, as well as a late positivity that was larger for congruent items. In Experiment 2, participants assessed the relatedness between probe words and preceding cartoon-gesture pairs. N450 effects to gestures were observed without overlapping positivity. These findings suggest that iconic gestures are subject to semantic processes analogous to those evoked by other meaningful representations, such as pictures and words.

Adult↗

PubMed2005

Right hemisphere activation of joke-related information: an event-related brain potential study.

Two studies tested the hypothesis that the right hemisphere engages in relatively coarse semantic coding that aids high-level language tasks such as joke comprehension. Scalprecorded event-related brain potentials (ERPs) were collected as healthy adults read probe words (CRAZY) preceded either by jokes or nonfunny controls ("Everyone had so much fun jumping into the swimming pool, we decided to put in a little water/platform"). Probes were related to the meaning of the jokes, but not the controls. In Experiment 1a, with central presentation, probes following jokes (related) elicited less negative ERPs 300-700 msec postonset (N400) than did probes following nonfunny controls (unrelated). This finding suggests related probes were primed by the jokes. In addition, unrelated probes elicited a larger anterior positivity 700-900 msec than did related, as irrelevant stimuli impacted control processes invoked by task demands. In Experiment 1b, probes (CRAZY) were preceded only by sentence-final words from jokes (water) or controls (platform). No ERP effects were observed in Experiment 1b, suggesting the N400 priming effect and the anterior positivity observed in Experiment 1a ref lect semantic activations at the discourse level. To assess hemispheric differences in semantic activations, in Experiment 2, ERPs were recorded as participants read probe words presented in their left and right visual fields (LVF and RVF, respectively). Probes elicited a smaller N400 component when preceded by jokes than controls. This N400 priming effect was larger with presentation to the LVF, suggesting joke-relevant information was more active in the right hemisphere. The anterior positivity was observed with RVF but not LVF presentation, suggesting an important role for the left hemisphere in controlled retrieval in language comprehension.

Acoustic Stimulation↗

PubMed2004

Handedness, hemispheric asymmetries, and joke comprehension.

To address the impact of differences in language lateralization on joke comprehension, event-related brain potentials (ERPs) were recorded as 16 left- and 16 right-handed adults read one-line jokes and non-funny control stimuli ("A replacement player hit a home run with my girl/ball,"). In right-handers, jokes elicited a late positivity 500-900 ms post-stimulus onset that was largest over right hemisphere (RH) centro-parietal electrode sites, and a slow sustained negativity over anterior left lateral sites. In left-handers, jokes elicited a late positivity 500-900 ms post-onset that was larger and more broadly distributed than in the right-handers' ERPs. In right-handed women, the late positivity was larger over RH electrode sites. In left-handed women, the late positivity was bilaterally symmetric. The highly asymmetric slow sustained negativity over left anterior electrode sites was absent from left-handers' ERPs to jokes. Differences may reflect more efficient inter-hemispheric communication in the left-handers, as they are reputed to have relatively larger corpus callosal areas than right-handers. Results support the portrait of more bilateral language representation among left-handers, and suggest language lateralization affects high-level language comprehension tasks such as joke comprehension.

Adolescent↗

PubMed2004

Syntactic processing with aging: an event-related potential study.

To assess age-related changes in simple syntactic processing with normal aging, event-related brain potentials (ERPs) elicited by grammatical number violations as individuals read sentences for comprehension were analyzed. Violations were found to elicit a P600 of equal amplitude and latency regardless of an individual's age. Instead, advancing age was associated with a change in the scalp distribution of the P600 effect, being less asymmetric and more frontal (though still with a parietal maximum) in older than younger adults. Our results thus show that the brain's response to simple syntactic violations, unlike those reported for simple binary categorizations and simple semantic violations, is neither slowed nor diminished in amplitude by age. At the same time, the brain's processing of these grammatical number violations did engage at least somewhat different brain regions as a function of age, suggesting a qualitative change rather than any simple quantitative change in speed of processing.

Adolescent↗

PubMed2002

Conceptual integration and metaphor: an event-related potential study.

Event-related brain potentials (ERPs) were recorded from 18 normal adults as they read sentences that ended with words used literally, metaphorically, or in an intermediate literal mapping condition. In the latter condition, the literal sense of the word was used in a way that prompted readers to map conceptual structure from a different domain. ERPs measured from 300 to 500 msec after the onset of the sentence-final words differed as a function of metaphoricity: Literal endings elicited the smallest N400, metaphors the largest N400, whereas literal mappings elicited an N400 of intermediate amplitude. Metaphoric endings also elicited a larger posterior positivity than did either literal or literal mapping words. Consistent with conceptual blending theory, the results suggest that the demands of conceptual integration affect the difficulty of both literal and metaphorical language.

Adult↗