Can contagious itch be affected by positive and negative suggestions?

Contagious itch can be evoked by observing people scratching. Verbal suggestions about to-be-received itch can influence itch intensity, as shown by placebo research, but it is unknown whether this extends to contagious itch. The current study aimed to replicate prior findings that listening to scratching and rubbing sounds elicits contagious itch, and to investigate whether suggestions can modulate this process. Healthy participants (n = 140) received positive or negative suggestions about itch in response to the sounds (aimed to decrease or increase expected itch, respectively), or no specific suggestions as a control. Participants listened to a number of audio fragments with scratching and rubbing sounds. The amount of expected itch as well as itch sensation after each audio fragment were measured by self-report. Suggestions had no effect on the expected itch. Both rubbing and scratching sounds significantly elicited itch in all groups. Scratching sounds induced more itch than rubbing sounds exclusively in the control group. These findings indicate that short suggestions might be not effective enough to modify the expectations of people regarding contagious itch. Furthermore, suggestions modulate contagious itch to some degree, but not in the hypothesized direction. Potential similarities and differences in the neurobiological mechanisms of contagious itch and nocebo effects are discussed.

The time course of lexical access in morphologically complex words.

Compounding, the concatenation of words (e.g. dishwasher), is an important mechanism across many languages. This study investigated whether access of initial compound constituents occurs immediately or, alternatively, whether it is delayed until the last constituent (i.e. the head). Electroencephalogram was measured as participants listened to German two-constituent compounds. Both the initial as well as the following head constituent could consist of either a word or nonword, resulting in four experimental conditions. Results showed a larger N400 for initial nonword constituents, suggesting that lexical access was attempted before the head. Thus, this study provides direct evidence that lexical access of transparent compound constituents in German occurs immediately, and is not delayed until the compound head is encountered.

Integration of iconic gestures and speech in left superior temporal areas boosts speech comprehension under adverse listening conditions.

Iconic gestures are spontaneous hand movements that illustrate certain contents of speech and, as such, are an important part of face-to-face communication. This experiment targets the brain bases of how iconic gestures and speech are integrated during comprehension. Areas of integration were identified on the basis of two classic properties of multimodal integration, bimodal enhancement and inverse effectiveness (i.e., greater enhancement for unimodally least effective stimuli). Participants underwent fMRI while being presented with videos of gesture-supported sentences as well as their unimodal components, which allowed us to identify areas showing bimodal enhancement. Additionally, we manipulated the signal-to-noise ratio of speech (either moderate or good) to probe for integration areas exhibiting the inverse effectiveness property. Bimodal enhancement was found at the posterior end of the superior temporal sulcus and adjacent superior temporal gyrus (pSTS/STG) in both hemispheres, indicating that the integration of iconic gestures and speech takes place in these areas. Furthermore, we found that the left pSTS/STG specifically showed a pattern of inverse effectiveness, i.e., the neural enhancement for bimodal stimulation was greater under adverse listening conditions. This indicates that activity in this area is boosted when an iconic gesture accompanies an utterance that is otherwise difficult to comprehend. The neural response paralleled the behavioral data observed. The present data extends results from previous gesture-speech integration studies in showing that pSTS/STG plays a key role in the facilitation of speech comprehension through simultaneous gestural input.

Electrophysiological evidence for incremental lexical-semantic integration in auditory compound comprehension.

The present study investigated the time-course of semantic integration in auditory compound word processing. Compounding is a productive mechanism of word formation that is used frequently in many languages. Specifically, we examined whether semantic integration is incremental or is delayed until the head, the last constituent in German, is available. Stimuli were compounds consisting of three nouns, and the semantic plausibility of the second and the third constituent was manipulated independently (high vs. low). Participants' task was to listen to the compounds and evaluate them semantically. Event-related brain potentials in response to the head constituents showed an increased N400 for less plausible head constituents, reflecting the lexical-semantic integration of all three compound constituents. In response to the second (less plausible) constituents, an increased N400 with a central-left scalp distribution was observed followed by a parietal positivity. The occurrence of this N400 effect during the presentation of the second constituents suggests that the initial two non-head constituents are immediately integrated. The subsequent positivity might be an instance of a P600 and is suggested to reflect the structural change of the initially constructed compound structure. The results suggest that lexical-semantic integration of compound constituents is an incremental process and, thus, challenge a recent proposal on the time-course of semantic processing in auditory compound comprehension.

The role of iconic gestures in speech disambiguation: ERP evidence.

The present series of experiments explored the extent to which iconic gestures convey information not found in speech. Electroencephalogram (EEG) was recorded as participants watched videos of a person gesturing and speaking simultaneously. The experimental sentences contained an unbalanced homonym in the initial part of the sentence (e.g., She controlled the ball ...) and were disambiguated at a target word in the subsequent clause (which during the game ... vs. which during the dance ...). Coincident with the initial part of the sentence, the speaker produced an iconic gesture which supported either the dominant or the subordinate meaning. Event-related potentials were time-locked to the onset of the target word. In Experiment 1, participants were explicitly asked to judge the congruency between the initial homonym-gesture combination and the subsequent target word. The N400 at target words was found to be smaller after a congruent gesture and larger after an incongruent gesture, suggesting that listeners can use gestural information to disambiguate speech. Experiment 2 replicated the results using a less explicit task, indicating that the disambiguating effect of gesture is somewhat task-independent. Unrelated grooming movements were added to the paradigm in Experiment 3. The N400 at subordinate targets was found to be smaller after subordinate gestures and larger after dominant gestures as well as grooming, indicating that an iconic gesture can facilitate the processing of a lesser frequent word meaning. The N400 at dominant targets no longer varied as a function of the preceding gesture in Experiment 3, suggesting that the addition of meaningless movements weakened the impact of gesture. Thus, the integration of gesture and speech in comprehension does not appear to be an obligatory process but is modulated by situational factors such as the amount of observed meaningful hand movements.