Understanding the role of executive control in the Implicit Association Test: Why flexible people have small IAT effects

The goal of the present research was to investigate the role of three central-executive functions—switching of mental sets, inhibition of prepotent responses, and simultaneous storage and processing (i.e., working-memory capacity)—in accounting for method variance in the Implicit Association Test (IAT). In two studies, several IATs with unrelated contents were administered along with a battery of central-executive tasks, with multiple tasks tapping each of the above executive functions. Method variance was found to be related to the switching factor, but not to the inhibition factor. There was also evidence for a small independent contribution of the working-memory capacity factor. The findings constrain process accounts of the IAT, lending support to an account in terms of task-set switching, and they have consequences for applications.     

Negative numbers in simple arithmetic

Are negative numbers processed differently from positive numbers in arithmetic problems? In two experiments, adults (N?=?66) solved standard addition and subtraction problems such as 3?+?4 and 7 – 4 and recasted versions that included explicit negative signs—that is, 3 – (–4), 7?+?(–4), and (–4)?+?7. Solution times on the recasted problems were slower than those on standard problems, but the effect was much larger for addition than subtraction. The negative sign may prime subtraction in both kinds of recasted problem. Problem size effects were the same or smaller in recasted than in standard problems, suggesting that the recasted formats did not interfere with mental calculation. These results suggest that the underlying conceptual structure of the problem (i.e., addition vs. subtraction) is more important for solution processes than the presence of negative numbers.     

Up north and down south: Implicit associations between topography and cardinal direction

Route planners show a reliable tendency to select south- relative to north-going routes between two horizontally (east/west) aligned landmarks, suggesting the application of a north-is-up heuristic (Brunyé, Mahoney, Gardony, & Taylor, 2010). The source of this north-is-up bias remains unknown, and there is no strong evidence to suggest that it is due to explicit strategy use. In four experiments, we attempt to further elucidate the source of this effect by testing whether it can be attributed to implicit associations between cardinal direction (north/south) and topography (mountainous/level terrain). Experiments 1 and 2 used an adapted Implicit Association Test and demonstrate automatically activated judgements that associate north with mountainous and south with relatively level terrain. Experiment 3 rules out the possibility that this effect is due to the local topography of New England by replicating in participants from the topographically dissimilar Midwestern United States. Finally, Experiment 4 tests the relative contribution of implicit versus explicit associations between cardinal direction and topography in predicting route-planning asymmetries; we show that implicit associations are a stronger predictor of southern route biases than explicit processes. Overall, results demonstrate that the conceptualization of space can be driven by physically unfounded implicit associations between cardinal directions and topographical features, and these associations are at least partially responsible for southern route preferences.     

The role of numerosity in processing nonsymbolic proportions

The difficulty in processing fractions seems to be related to the interference between the whole-number value of the numerator and the denominator and the real value of the fraction. Here we assess whether the reported problems with symbolic fractions extend to the nonsymbolic domain, by presenting fractions as arrays of black and white dots representing the two operands. Participants were asked to compare a target array with a reference array in two separate tasks using the same stimuli: a numerosity task comparing just the number of white dots in the two arrays; and a proportion task comparing the proportion of black and white dots. The proportion task yielded lower accuracy and slower response, confirming that even with nonsymbolic stimuli accessing proportional information is relatively difficult. However, using a congruity manipulation in which the greater numerosity of white dots could co-occur with a lower proportion of them, and vice versa, it was found that both task-irrelevant dimensions would interfere with the task-relevant dimension suggesting that both numerosity and proportion information was automatically accessed. The results indicate that the magnitude of fractions can be automatically and holistically processed in the nonsymbolic domain.     

The spatial representation of numerical and non-numerical ordered sequences: Insights from a random generation task

It is widely believed that numbers are spatially represented from left to right on the mental number line. Whether this spatial format of representation is specific to numbers or is shared by non-numerical ordered sequences remains controversial. When healthy participants are asked to randomly generate digits they show a systematic small-number bias that has been interpreted in terms of “pseudoneglect in number space”. Here we used a random generation task to compare numerical and non-numerical order. Participants performed the task at three different pacing rates and with three types of stimuli (numbers, letters, and months). In addition to a small-number bias for numbers, we observed a bias towards “early” items for letters and no bias for months. The spatial biases for numbers and letters were rate independent and similar in size, but they did not correlate across participants. Moreover, letter generation was qualified by a systematic forward direction along the sequence, suggesting that the ordinal dimension was more salient for letters than for numbers in a task that did not require its explicit processing. The dissociation between numerical and non-numerical orders is consistent with electrophysiological and neuroimaging studies and suggests that they rely on at least partially different mechanisms.     

Impairment of gaze-directed spatial coding in recent-onset schizophrenia

Patients with schizophrenia show deficits in core cognitive functions as well as in social cognition. The aim of the present study was to test whether deficits in social cognition influence nonsocial, “cold”, cognition. Thirty-five patients with recent-onset schizophrenia (SC) and 30 healthy controls (HC) performed a Simon task with social and simple geometric stimuli. We investigated whether the Simon effect, the slowing of reaction times produced by stimulus incongruities in the task-irrelevant spatial domain, differs between patients and healthy participants as a function of the social nature of the cues. The Simon effect was generated by a schematic drawing of human eyes (social cues) or rectangles (nonsocial cues). Overall, patients had longer reaction times than HC. In the eye-like condition, the Simon effect was significantly stronger for HC than for SC. In HC the Simon effect was significantly stronger in the eye-like than in the rectangle condition. In patients, the Simon effect did not differ significantly between both conditions. Thus, the influence of social cues was greatly reduced in the patient group. Current psychopathology or antipsychotic treatment did not influence results. The present study supports earlier findings of altered processing of schematic social cues in patients with schizophrenia, especially when gaze is task-irrelevant.     

Age-related decline in the reflexive component of overt gaze following

Previous research has found age-related declines in social perception tasks as well as the ability to engage in joint attention and orienting covert attention (i.e., absence of eye movements) in response to an eye gaze cue. We used an overt gaze following task to explore age differences in overt gaze following whilst people searched for a target. Participants were faster to detect targets appearing at the looked-at location, and although the gaze cue biased the direction in which saccades were executed, no age differences were found in overt gaze following. There were, however, age effects relating to involuntary eye movements. In the younger adults, anticipatory saccades were biased in the direction of the gaze cue, but this bias was not observed in the older group. Moreover, in the younger adults, saccades that followed the gaze were initiated more rapidly, illustrating the reflexive nature of gaze following. No such difference was observed in the older adults. Importantly, our results showed that whilst the general levels of gaze following were age invariant, there were age-related differences in the reflexive components of overt gaze following.     

Mental rotation performance in soccer players and gymnasts in an object-based mental rotation task

In this study, the effect of motor expertise on an object-based mental rotation task was investigated. 60 males and 60 females (40 soccer players, 40 gymnasts, and 40 non-athletes, equivalent males and females in each group) solved a psychometric mental rotation task with both cube and human figures. The results revealed that all participants had a higher mental rotation accuracy for human figures compared to cubed figures, that the gender difference was reduced with human figures, and that gymnasts demonstrated a better mental rotation performance than non-athletes. The results are discussed against the background of the existing literature on motor experts, mental rotation performance as well as the importance of the testing situation and the test construction.     

Limiting attentional resources influences performance and output monitoring of an event-based prospective memory task

One of the most frequently used markers in research on numerical cognition is the distance effect. Recently, we have suggested that a distance effect can have different origins depending on the experimental task. By dissociating the comparison distance effect from the priming distance effect we revealed the need to study the origin of this effect before drawing any conclusions from it (van Opstal, Gevers, de Moor, &; Verguts, 2008). Because a distance effect in a same–different task is also commonly used to study number representations (e.g., Dehaene &; Akhavein, 1995), the present study aimed at uncovering the origin of the effect in this task. Computational and empirical results indicate clearly that the distance effect in the same–different task originates from number representations rather than a decision process.