Abstract and Introduction
This study measured event-related potentials (ERPs) during multiple goal and trait inferences, under spontaneous or intentional instructions. Participants read sentences describing several goal-implying behaviors of a target person from which also a strong trait could be inferred or not. The last word of each sentence determined the consistency with the inference induced during preceding sentences. In comparison with behaviors that implied only a goal, stronger waveforms beginning at~150 ms were obtained when the behaviors additionally implied a trait. These ERPs showed considerable parallels between spontaneous and intentional inferences. This suggests that traits embedded in a stream of goal-directed behaviors were detected more rapidly and automatically than mere goals, irrespective of the participants' spontaneous or intentional instructions. In line with this, source localization (LORETA) of the ERPs show predominantly activation in the temporo-parietal junction (TPJ) during 150–200 ms, suggesting that goals were detected at that time interval. During 200–300 ms, activation was stronger at the medial prefrontal cortex (mPFC) for multiple goals and traits as opposed to goals only, suggesting that traits were inferred during this time window. A cued recall measure taken after the presentation of the stimulus material support the occurrence of goal and trait inferences and shows significant correlations with the neural components, indicating that these components are valid neural indices of spontaneous and intentional social inferences. The early detection of multiple goal and trait inferences is explained in terms of their greater social relevance, leading to privileged attention allocation and processing in the brain.
IntroductionWe look at a person and immediately a certain impression of his character forms itself in us. A glance, a few spoken words are sufficient to tell us a story about a highly complex matter. We know that such impressions form with remarkable rapidity and with great ease
Asch, 1946, p. 258
In social interaction, the perceived intentions and attributes of other people are critical in initiating and maintaining smooth communication and cooperation, as well as avoiding undesirable or dangerous encounters. Sometimes, these social inferences are so essential for our survival that we must make them very rapidly and automatically. Is the other person concealing a present or making a fist? Is he or she friendly or aggressive? Little time to ponder alternatives is available when we are confronted with potentially threatening behaviors. This research is concerned with the processing of goal and trait inferences, the time it requires to make such judgments and which regions in the brain are involved in this process. Past neuroscientific research has explored how single inferences of other's goals, traits and beliefs are processed in the brain (e.g. Van Duynslaeger et al., 2007; Van der Cruyssen et al., 2008; Van Duynslaeger et al., 2008; for a review see Van Overwalle, 2008). Hence, the critical question addressed in this article is how multiple inferences of this kind interact. Knowing how fast multiple as opposed to single social inferences are made and which brain areas they involve within the same participants, could allow us to gain better insight in the psychological processes and behavioral consequences underlying these inferences.
Given the greater functional relevance of multiple inferences, one might assume that information diagnostic of combined goals and traits is privileged in social processing, leading to faster and stronger brain activation. Such privileged processing might be most relevant under constraints of limited time and resources, when intuitive and quick inferences and decisions are most advantageous. To investigate this, we explored not only multiple inferences when making these intentionally (e.g. when given ample time or incentives to think about them), but also and most critically when making these spontaneously (under little time or incentives, e.g. while doing other routine activities). Many dual-process models in social cognition and social neuroscience distinguish between spontaneous associative processes and intentional (controlled) symbolic reasoning (Smith and DeCoster, 2000; Satpute and Lieberman, 2006; Keysers and Gazzola, 2007). Behavioral and neurological research has convincingly demonstrated that goal and trait inferences can be activated spontaneously (e.g. Hassin et al., 2005; Van Duynslaeger et al., 2007; Van der Cruyssen et al., 2008). Making such inferences requires almost no intention or awareness, involves only little mental effort, and is difficult to suppress or modify (for a review, see Uleman et al., 2005).
In line with this functional approach to social inference, recent research has sought more neuroscientific evidence to gain insight in the timing of social brain processes and has turned to event-related potentials (ERP). ERPs are waveforms that reflect electric activity of the brain during responses to specific stimuli, and their timing reveals the processing stage at which social inferences are identified. This research has documented that inferences about another person's goals are made about 200 ms after presenting a critical word implying the goal of an actor (Van der Cruyssen et al., 2008). This timing has been uncovered by comparing behavioral descriptions that are consistent as opposed to irrelevant with previous goal-implying information about the actor. For instance, after reading about several activities that induce the goal inference 'preparing a party' (e.g. putting up decorations, preparing food, calling friends), our brain very rapidly reacts when irrelevant information is presented (e.g. searching his pet), as shown by early deviations in ERP waveforms. These waveforms show considerable parallels between spontaneous and intentional goal inferences, indicating that goals are inferred automatically at about 200 ms, irrespective of the observer's processing intentions. Research using a similar paradigm has demonstrated that it takes considerably longer—about 400–600 ms post-stimulus—to infer stable personality traits about another person (Van Duynslaeger et al., 2007, 2008). To illustrate, after reading about a person who kisses his daughter and hugs his father which induce the trait inference 'friendly', when that same person subsequently slaps his mother, ERP deviations reveal that our brain detects this trait inconsistency in about half a second.