A drift diffusion model account of the semantic congruity effect in a classification paradigm

The semantic congruity effect refers to the facilitation of judgements (i) when the direction of the comparison of two items coincides with the relative position of the items along the dimension comparison or (ii) when the relative size of a standard and a target stimulus coincides. For example, people are faster in judging 'which is bigger?' for two large items, than judging 'which is smaller?' for two large items (selection paradigm). Also, people are faster in judging a target stimulus as smaller when compared to a small standard, than when compared to a large standard, and vice versa (classification paradigm). We use the Drift Diffusion Model (DDM) to explain the time course of a semantic congruity effect in a classification paradigm. Formal modelling of semantic congruity allows the time course of the decision process to be described, using an established model of decision making. Moreover, although there have been attempts to explain the semantic congruity effect within evidence accumulation models, two possible accounts for the congruity effect have been proposed but their specific predictions have not been compared directly, using a model that could quantitatively account for both; a shift in the starting point of evidence accumulation or a change in the rate at which evidence is accumulated. With our computational investigation we provide evidence for the latter, while controlling for other possible explanations such as a variation in non-decision time or boundary separation, that have not been taken into account in the explanation of this phenomenon.

Moral Severity is Represented as a Domain-General Magnitude

The severity of moral violations can vary by degree. For instance, although both are immoral, murder is a more severe violation than lying. Though this point is well established in Ethics and the law, relatively little research has been directed at examining how moral severity is represented psychologically. Most prominent moral psychological theories are aimed at explaining first-order moral judgments and are silent on second-order metaethical judgments, such as comparisons of severity. Here, the relative severity of 20 moral violations was established in a preliminary study. Then, a second group of participants were asked to decide which of two moral violations was more severe for all possible combinations of these 20 violations. Participant’s response times exhibited two signatures of domain-general magnitude comparisons: we observed both a distance effect and a semantic congruity effect. These findings suggest that moral severity is represented in a similar fashion as other continuous magnitudes.

Holistic Representation of Unit Fractions

The present study examined the processing of unit fractions and the extent to which it is affected by context. Using a numerical comparison task we found evidence for a holistic representation of unit fractions when the immediate context of the fractions was emphasized, that is when the stimuli set included in addition to the unit fractions also the numbers 0 and 1. The holistic representation was indicated by the semantic congruity effect for comparisons of pairs of fractions and by the distance effect in comparisons of a fraction and 0 and 1. Consistent with previous results (Bonato, Fabbri, Umilta, & Zorzi, 2007) there was no evidence for a holistic representation of unit fractions when the stimulus set included only fractions. These findings suggest that fraction processing is context-dependent. Finally, the present results are discussed in the context of processing other complex numbers beyond the first decade.

“1-2-3”: Is There a Temporal Number Line?

Evidence suggests that numbers are intimately related to space ( Dehaene, Bossini, & Giraux, 1993 ; Hubbard, Piazza, Pinel, & Dehaene, 2005 ). Recently, Walsh (2003) suggested that numbers might also be closely related to time. To investigate this hypothesis we asked participants to compare two digits that were presented in a serial manner, i.e., one after another. Temporally ascending digit pairs (such as 2-3) were responded to faster than temporally descending pairs (3-2). This effect was, in turn, qualified by a local SNARC (spatial numerical association of response codes) effect and a local semantic congruity effect (SCE). Moreover, we observed a global numerical SCE only for temporally descending digit pairs. However, we did not observe a global SNARC effect, i.e., an interaction of numerical magnitude and the right/left response hand. We discuss our results in terms of overlearned forward-associations (“1-2-3”) as formed by our ubiquitous cognitive routines to count off objects or events.

Effects of Semantic and Syntactic Congruity on Incidental Free Recall in Japanese Sentences

Effects of the semantic and the syntactic congruity of sentence contexts on free recall were investigated in an incidental memory paradigm using an orienting task. All subjects were required to decide whether each target made sense in its sentence context on the orienting task. The subjects in a fast/quick group were presented each target for 2 sec. and given instructions which emphasized a quick decision. The subjects in the slow/accurate group were presented each target for 10 sec. and given instructions which emphasized the accuracy of the decision. Three types of sentence contexts were provided: semantically and syntactically congruous, semantically incongruous and syntactically congruous, and semantically and syntactically incongruous. For the fast/quick group only the semantic congruity effect was observed. Semantically and syntactically congruous sentence frames led to a better recall than semantically incongruous and syntactically congruous ones. For the slow/accurate group both the semantic congruity effects and the syntactic congruity effects were observed. Semantically incongluous and syntactically congruous sentences led to a better recall than semantically and syntactically incongruous ones. The difference between both types of congruity effects was discussed in terms of the encoding time of the semantic and the syntactic congruities.