The acquisition of odour qualities

Odours can evoke a large range of qualities. Some of these qualities (e.g., sweetness) appear to be acquired through simultaneously experiencing odours mixed with tastes. Acquisition might also occur when two odours are experienced as a mixture. In this case mixture components might acquire each other's qualities. This was tested in two experiments. In the first, subjects repeatedly sniffed two odour mixtures (either AX, BY or AY, BX). Odours mixed with A acquired A's properties and were judged more similar to A than to B. Odours mixed with B were not clearly discriminable. The second experiment used a similar approach except that Odour B was replaced. Subjects now smelled either AX, CY or AY, CX. All components were discriminable. Odours mixed with A acquired A's properties and were judged more similar to A than to C. Although odours mixed with C did not acquire C's qualities due to a confusion of quality terms, odours previously mixed with C were judged as more similar to C than to A. Evidence of other quality exchanges were also obtained. These results suggest that pure odour qualities can be learnt and lend support to William James's (1890) notion of the acquired equivalence/distinctiveness of cues.     

Deduction from Uncertain Premises

We investigate how the perceived uncertainty of a conditional affects a person's choice of conclusion. We use a novel procedure to introduce uncertainty by manipulating the conditional probability of the consequent given the antecedent. In Experiment 1, we show first that subjects reduce their choice of valid conclusions when a conditional is followed by an additional premise that makes the major premise uncertain. In this we replicate Byrne (1989). These subjects choose, instead, a qualified conclusion expressing uncertainty. If subjects are given a third statement that qualifies the likelihood of the additional premise, then the uncertainty of the conclusions they choose is systematically related to the suggested uncertainty. Experiment 2 confirms these observations in problems that omit the additional premise and qualify the first premise directly. Experiment 3 shows that the qualifying statement also affects the perceived probability of the consequent given the antecedent of the conditional. Experiment 4 investigates the effect of suggested uncertainty on the fallacies and shows that increases in uncertainty reduce the number of certain conclusions that are chosen while affirming the consequent but have no effect on denying the antecedent. We discuss our results in terms of rule theories and mental models and conclude that the latter give the most natural account of our results.