When Does a Reasoner Respond: Nothing Follows?

AbstractWhen does a reasoner respond that ”no valid conclusion” (NVC) follows in a syllogistic reasoning task? Cognitive theories aim to trace it back to theory specific inference processes. In contrast, systemic theories explain it by depleted cognitive resources among others. This paper investigates possible theories to explain NVC responses in an experiment with 139 participants. Using mixed models we analyze the association of NVC responses with reaction times, the validity as well as the entropy of a syllogism, and how NVC responses change over time. As expected, the number of NVC responses is lower than logically expected, participants respond NVC more often for invalid syllogisms, and the likelihood to respond NVC increases over the time-course of the experiment. Surprisingly, however, only for valid syllogisms, are the entropy and the RTs associated with NVC responses. Consequently, for invalid syllogisms, NVC responses seem to be generated differently as compared to valid ones.

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