Social and Nonsocial Relational Reasoning in Adolescence and Adulthood

Abstract

Reasoning during social interactions requires the individual manipulation of mental representations of one's own traits and those of other people as well as their joint consideration (relational integration). Research using nonsocial paradigms has linked relational integration to activity in the rostrolateral PFC. Here, we investigated whether social reasoning is supported by the same general system or whether it additionally relies on regions of the social brain network, such as the medial PFC. We further assessed the development of social reasoning. In the social task, participants evaluated themselves or a friend, or compared themselves with their friend, on a series of traits. In the nonsocial task, participants evaluated their hometown or another town or compared the two. In a behavioral study involving 325 participants (11-39 years old), we found that integrating relations, compared with performing single relational judgments, improves during adolescence, both for social and nonsocial information. Thirty-nine female participants (10-31 years old) took part in a neuroimaging study using a similar task. Activation of the relational integration network, including the rostrolateral PFC, was observed in the comparison condition of both the social and nonsocial tasks, whereas the medial PFC showed greater activation when participants processed social as opposed to nonsocial information across conditions. Developmentally, the right anterior insula showed greater activity in adolescents compared with adults during the comparison of nonsocial versus social information. This study shows parallel recruitment of the social brain and the relational reasoning network during the relational integration of social information in adolescence and adulthood.

Figure 1

Example of stimuli for each task and condition. The Vowels condition was only included in Study 2. In the People task, participants were asked: “How much do you think the following words apply to you/your friend?” (Self/Other) or “How much do you think the following words apply to you compared with your friend?” (Comparison). On the rating scale, 1 indicated “not at all” and 6 indicated “very much so” in the Self and Other conditions, whereas 1 indicated “much less so” and 6 indicated “much more so” in the Comparison condition. All text was presented in white on a black background.

Figure 2

Mean RT and consistency scores as a function of age group. (A) Study 1: mean RTs as a function of Age group and Condition. (B) Study 1: mean difference in RTs between the Comparison and Self and Other conditions as a function of Age group. (C) Study 1: mean consistency scores as a function of Age group. (D) Study 2: mean consistency scores as a function of Age group. Error bars represent SE. ^†p < .1, *p < .05, **p < .01, ***p < .001 (Bonferroni corrected). y = years.

Figure 3

fMRI results across age groups. (A) Main effect of Condition. Regions showing increased BOLD signal in Comparison (2-REL) compared with Self and Other (1-REL) conditions are rendered on the SPM8 surface mesh template. From left to right: lateral view of the left hemisphere, medial and lateral views of the right hemisphere. (B) Main effect of Task. Regions showing increased BOLD signal in the People compared with the Town task are rendered on the SPM8 surface mesh template (medial view of the right hemisphere).

Figure 4

fMRI results of the interaction between Task, Condition, and Age group. On the left, the right anterior insula cluster showing a three-way interaction between Task, Condition, and Age group is shown on an average structural scan of all participants in the study (left: y = 21, right: z = 0). The contrast was thresholded at p < .001 uncorrected at the voxel level, p_FWE < .05 at the cluster level. On the right, parameter estimates extracted from this cluster are plotted in a bar chart to illustrate the three-way interaction. Error bars represent SE. ^†p < .1, *p < .05, **p < .01, ***p < .001.