Perceived communicative context and emotional content amplify visual word processing in the fusiform gyrus

Abstract

The personal significance of a language statement depends on its communicative context. However, this is rarely taken into account in neuroscience studies. Here, we investigate how the implied source of single word statements alters their cortical processing. Participants' brain event-related potentials were recorded in response to identical word streams consisting of positive, negative, and neutral trait adjectives stated to either represent personal trait feedback from a human or to be randomly generated by a computer. Results showed a strong impact of perceived sender. Regardless of content, the notion of receiving feedback from a human enhanced all components, starting with the P2 and encompassing early posterior negativity (EPN), P3, and the late positive potential (LPP). Moreover, negative feedback by the "human sender" elicited a larger EPN, whereas positive feedback generally induced a larger LPP. Source estimations revealed differences between "senders" in visual areas, particularly the bilateral fusiform gyri. Likewise, emotional content enhanced activity in these areas. These results specify how even implied sender identity changes the processing of single words in seemingly realistic communicative settings, amplifying their processing in the visual brain. This suggests that the concept of motivated attention extends from stimulus significance to simultaneous appraisal of contextual relevance. Finally, consistent with distinct stages of emotional processing, at least in contexts perceived as social, humans are initially alerted to negative content, but later process what is perceived as positive feedback more intensely.

Keywords: EEG/ERP; emotion; fusiform gyri; language; social feedback; social neuroscience.

Figure 1.

Trial presentation in the fictitious interactive software environment. Each trial started with a presented trait adjective. Subsequent color change indicated endorsement of a trait.

Figure 2.

Results for the EPN time window displaying the significant main effect for the communicative sender and the interaction between communicative sender and emotional content. a, Left, Difference topographies for the communicative sender. Blue color indicates more negativity and red color more positivity for decisions from the “human sender.” Right, Selected electrode PO9 displaying the time course for both senders. b, Left, Difference topographies for the “human sender” and “computer sender.” Right, Selected electrode PO9h displaying the time course for all decisions from both senders. Mean amplitudes in microvolt for the occipital EPN cluster are shown at bottom. For display purposes, electrodes were filtered using a 15 Hz low-pass filter.

Figure 3.

EPN: source estimations for the comparison between the “human sender” and the “computer sender” (displayed are the FWE-corrected t-contrasts). Decisions by the “human sender” led to enhanced activations in the bilateral fusiform gyri in the EPN time window.

Figure 4.

Main effect of the communicative sender over the central cluster in the P2, P3, and early and late LPP time windows. Top, Difference topographies for the communicative sender. Blue color indicates more negativity and red more positivity for the “human sender.” Bottom, Selected electrode Pz displaying the time course for both senders. For display purposes, data were filtered using a 15 Hz low-pass filter.

Figure 5.

Main effect of emotion over the central cluster in the late LPP time window. Left, Difference topographies between emotional and neutral decisions. Blue color indicates more negativity and red more positivity for emotional decisions. Right, Selected electrode CPPz illustrates the time course for negative, neutral, and positive decisions. Mean amplitudes in microvolt for the central late LPP cluster are shown at bottom. For display purposes, data were filtered using a 15 Hz low-pass filter.

Figure 6.

Late LPP: source estimations for the comparison between emotional and neutral decisions within ROIs derived from sender main effects (shown are the FWE-corrected t-contrasts). Emotional decisions led to larger activity in bilateral fusiform gyri.