Knowledge that Transforms

In a recent article, Dijksterhuis and Aarts (2003) investigated the preferential detection of negative stimuli. According to them, their data clearly indicate that it requires less stimulus input or less stimulus exposure to detect a negative stimulus than to detect a positive stimulus. However, we believe their research suffers from a number of limitations and methodological flaws that cast doubt on their conclusions. Using signal detection analyses, we demonstrate that none of their three studies provides sufficiently informative data with respect to their hypotheses. Moreover, we show that their experimental designs seem to be inadequate to test their hypotheses.

It is well known that under normal circumstances, human observers are able to detect a visual change (a luminance transient) in the outside world very easily. This study demonstrated that observers are also easily able to detect a nonchanging element if it is located in a display containing multiple elements that do change. That is, a nonchanging element popped out from a display containing multiple changing elements (luminance transients). The efficient detection of the nonchanging element may be due to temporal grouping created by the dynamic character of the stimulus display.

A visual search experiment using synthetic three-dimensional objects is reported. The target shared its constituent parts, the spatial organization of its parts, or both with the distractors displayed with it. Sharing of parts and sharing of spatial organization both negatively affected visual search performance, and these effects were strictly additive. These findings support theories of complex visual object perception that assume a parsing of the stimulus into its higher-order constituents (volumetric parts or visible surfaces). The additivity of the effects demonstrates that information on parts and information on spatial organization are processed independently in visual search.

A dominant account of perseverative errors in early development contends that such errors reflect a failure to inhibit a prepotent response. This study investigated whether perseveration might also arise from a failure to inhibit a prepotent representation. Children watched as a toy was hidden at an A location, waited during a delay, and then watched the experimenter find the toy. After six observation-only A trials, the toy was hidden at a B location, and children were allowed to search for the toy. Two- and 4-year-olds' responses on the B trials were significantly biased toward A even though they had never overtly responded to this location. Thus, perseverative biases in early development can arise as a result of prepotent representations, demonstrating that the prepotent-response account is incomplete. We discuss three alternative interpretations of these results, including the possibility that representational and response-based biases reflect the operation of a single, integrated behavioral system.

Following brain damage, skilled readers may encounter more severe problems in reading nonwords than familiar words, a type of deficit referred to as phonological dyslexia. We report on 2 individuals with Alzheimer's disease who show phonological dyslexia. Although highly accurate in reading familiar words aloud (even those with irregular spelling, such as sew), they were quite impaired in nonword reading. Both patients performed well in phonological tasks involving the repetition, identification, and manipulation of phonemes of orally presented words and nonwords. These results challenge the idea, proposed in the context of connectionist and evolutionary theories, that phonological dyslexia originates from a phonological deficit. However, the results are consistent with reading models, such as the dual-route model, that attribute phonological dyslexia to a deficit that selectively affects the reading mechanisms responsible for deriving the sounds of nonwords. According to these models, such a deficit is not necessarily accompanied by a more general phonological impairment.

Cognition is shaped by the way that past experiences are represented in memory. To examine the representation of recent visual experiences, we devised a novel procedure that measures episodic recognition memory for synthetic textures. On each trial, two brief study stimuli were followed by a probe, which either replicated one of the study stimuli or differed in spatial frequency from both. The probe's spatial frequency roved from trial to trial, testing recognition with a range of differences between probe and study items. Repeated testing of recognition generated mnemometric functions, snapshots of memory strength's distribution. The distributional characteristics of the mnemometric functions rule out several hypotheses about memory representation, including the hypothesis that representations are prototypes constructed from previously seen stimuli; instead, stimuli are represented in memory as noisy exemplars.

IMF supported programs include key objectives (such as growth, inflation, and current account adjustment) and the intermediate policy targets (such as monetary and fiscal policies) needed to achieve these objectives. In this paper, we use a new, large dataset, with information on 94 programs between 1989 and 2002, to compare programmed objectives and policy targets to actual outturns, and report two broad sets of results. Regarding objectives, we find that outturns typically fell short of expectations in the areas of growth and inflation, but were broadly in line with the programmed external current account objectives. Regarding the intermediate policy targets, programmed policies were generally more ambitious than policy outturns, and we document the extent of this difference. Second, focusing on growth, we examine the relationship between objectives and policy targets and find a difference in the way ambitious monetary and fiscal targets affected the achievement of the growth objective. Regarding fiscal targets, even when they were missed, if they were more ambitious, the performance on growth was better. On the other hand, more ambitious monetary targets, tended to reduced growth performance.

Three studies involving 257 undergraduates examined whether a simple choice reaction time task could predict daily experiences of affect. Individuals who were fast to make negative evaluations experienced more negative affect and more somatic symptoms and were less satisfied with their lives, compared with individuals who were slow to make negative evaluations. A fourth study, involving 89 undergraduates, indicated that performance on the task was relatively unaffected by transitory mood states. The results support the idea that categorization provides a useful perspective on personality functioning.