Neural Interaction between Logical Reasoning and Pragmatic Processing in Narrative Discourse

Abstract

Logical connectives (e.g., or, if, and not) are central to everyday conversation, and the inferences they generate are made with little effort in pragmatically sound situations. In contrast, the neural substrates of logical inference-making have been studied exclusively in abstract tasks where pragmatic concerns are minimal. Here, we used fMRI in an innovative design that employed narratives to investigate the interaction between logical reasoning and pragmatic processing in natural discourse. Each narrative contained three premises followed by a statement. In Fully-deductive stories, the statement confirmed a conclusion that followed from two steps of disjunction-elimination (e.g., Xavier considers Thursday, Friday, or Saturday for inviting his girlfriend out; he removes Thursday before he rejects Saturday and declares "I will invite her out for Friday"). In Implicated-premise stories, an otherwise identical narrative included three premises that twice removed a single option from consideration (i.e., Xavier rejects Thursday for two different reasons). The conclusion therefore necessarily prompts an implication (i.e., Xavier must have removed Saturday from consideration as well). We report two main findings. First, conclusions of Implicated-premise stories are associated with more activity than conclusions of Fully-deductive stories in a bilateral frontoparietal system, suggesting that these regions play a role in inferring an implicated premise. Second, brain connectivity between these regions increases with pragmatic abilities when reading conclusions in Implicated-premise stories. These findings suggest that pragmatic processing interacts with logical inference-making when understanding arguments in narrative discourse.

At the core of reasoning: Dissociating deductive and non‐deductive load

“…Consistent with previous reports, our results favor the idea that deductive reasoning is supported by a distributed network of regions encompassing frontal and parietal areas (Monti et al, ; Rodriguez‐Moreno & Hirsch, ; Prado et al, ). In light of recent discussions concerning the replicability of psychological and neuroimaging findings (Barch & Yarkoni, ; Pashler & Wagenmakers, ) it is particularly noteworthy that coordinates of the activation foci reported here match closely those reported in three previous experiments by our group (Monti et al, ; see Supporting Information Figure S12 for a visual comparison) despite different samples, stimuli, MR systems, and analysis methods.…”

“…On the other hand, a number of studies have failed to uncover any significant activation within Broca's area for propositional and categorical deductive inferences (Canessa et al, ; Kroger, Nystrom, Cohen, & Johnson‐Laird, ; Monti, Osherson, Martinez, & Parsons, ; Monti, Parsons, & Osherson, ; Noveck, Goel, & Smith, ; Parsons & Osherson, ; Rodriguez‐Moreno & Hirsch, ), even under much more naturalistic experimental conditions (Prado et al, ). An alternative hypothesis has thus been proposed under which logic is subserved by a set of language‐independent regions within frontopolar (i.e., BA10) and frontomedial (i.e., BA8) cortices, among others (Monti & Osherson, ; Monti et al, ).…”

“…Posterior parietal cortices, for example, are often observed across propositional, categorical, and relational deductive syllogisms, although with a preponderance of unilateral activations in propositional and categorical deductions and bilateral activations for relational problems (e.g., Knauff, Fangmeier, Ruff, & Johnson‐Laird, ; Knauff, Mulack, Kassubek, Salih, & Greenlee, ; Kroger et al, ; Monti et al, ; Noveck et al, ; Prado, Der Henst, & Noveck, ; Reverberi et al, ; Rodriguez‐Moreno & Hirsch, ). Dorsolateral frontal regions also appear to be recruited across different types of deductive problems (e.g., Fangmeier, Knauff, Ruff, & Sloutsky, ; Knauff et al, ; Monti et al, ; Reverberi et al, ; Rodriguez‐Moreno & Hirsch, ) and might possess interesting hemispheric asymmetries in their functional contributions to deductive inference making (see discussion in Prado et al, ). Nonetheless, the present study is specifically meant to address the significance of regions that have been previously proposed to encapsulate processes which lie at the heart of deductive reasoning (Monti et al, ) vis‐à‐vis the concern that it is “[…] not clear whether the results found by Monti et al () reflect deduction or working memory demands” (Kroger et al, , p. 90).…”

The neural development of pragmatic inference‐making in natural discourse

“…Following Prado et al (2015), fMRI data were analyzed using a Region of Interest (ROI) approach. Specifically, we aimed to measure activity in brain networks involved in inference-making and ToM.…”

“…Therefore, we defined bilateral ROIs in each of these regions based on coordinates from our previous study on adult participants that employed the same task . In line with Prado et al (2015), all ROIs were 6-mm radius spheres and were defined using the SPM toolbox Marsbar. ToM ROIs were located in the bilateral TPJ, the mPFC and the PC (Table 2).…”