Deduction without awareness

Abstract

We investigated whether two basic forms of deductive inference, Modus Ponens and Disjunctive Syllogism, occur automatically and without awareness. In Experiment 1, we used a priming paradigm with a set of conditional and disjunctive problems. For each trial, two premises were shown. The second premise was presented at a rate designed to be undetectable. After each problem, participants had to evaluate whether a newly-presented target number was odd or even. The target number matched or did not match a conclusion endorsed by the two previous premises. We found that when the target matched the conclusion of a Modus Ponens inference, the evaluation of the target number was reliably faster than baseline even when participants reported that they were not aware of the second premise. This priming effect did not occur for any other valid or invalid inference that we tested, including the Disjunctive Syllogism. In Experiment 2, we used a forced-choice paradigm in which we found that some participants were able to access some information on the second premise when their attention was explicitly directed to it. In Experiment 3, we showed that the priming effect for Modus Ponens was present also in subjects who could not access any information about P(2). In Experiment 4 we explored whether spatial relations (e.g., "a before b") or sentences with quantifiers (e.g., "all a with b") could generate a priming effect similar to the one observed for Modus Ponens. A priming effect could be found for Modus Ponens only, but not for the other relations tested. These findings show that the Modus Ponens inference, in contrast to other deductive inferences, can be carried out automatically and unconsciously. Furthermore, our findings suggest that critical deductive inference schemata can be included in the range of high-level cognitive activities that are carried out unconsciously.

The logic-bias effect: The role of effortful processing in the resolution of belief–logic conflict

“…The use of disjunctive arguments would also allow us to determine whether the findings can be extended to these more complex inferences. Reverberi et al (2012) found that disjunctive arguments did not produce the same priming effects as MP arguments, proposing that disjunctions require more effortful processing. Additionally, Handley et al (2011) replicated their initial findings using disjunctive arguments.…”

“…It has been argued that MP inferences are drawn automatically through direct rules of inference (Braine & O'Brien 1991) that can be triggered by subliminal stimuli and carried out automatically, even without instructions (Reverberi, Burigo, & Cherubini, 2009;Reverberi, Pischedda, Burigo, & Cherubini, 2012;Rips, 1988). However, in Experiment1, MP arguments were influenced, albeit to a small extent, by a secondary load, which suggests that they are not implicit in nature.…”

Against dispositionalism: belief in cognitive science

“…While conscious reasoning often feels like a whirlwind of ''mental chaos'' (Siegel 2017, 99), unconscious inference seems to be automatic and syntactic. When subjects are presented with a semantically sparse but syntactically well-formed sentence like 'If there is a 3 then there is an 8', and are then subliminally presented with '3', they show facilitation for '8' (Reverberi et al 2012). Subliminally presenting '8', however, does not facilitate '3'.…”

Believing in Perceiving: Known Illusions and the Classical Dual‐Component Theory

“…There is more recent evidence that deductive inferences are performed automatically (Handley et al, 2011; also see Braine and O'Brien, 1998 for a compendium of results in the 'mental logic' research program) and unconsciously (Reverberi et al, 2012). This evidence suggests that inferential promiscuity is actualized independently of whether the subject knows about or endorses the relevant beliefs (see Quilty-Dunn and Mandelbaum, manuscript, for further discussion).…”