Paying attention to meaning

Abstract— Several paradigms show that responses to one event compromise responses to a second event for around 500 ms. Such effects are generally attributed to attentional capacity limitations associated with processing information in the first event. In a task in which targets could be distinguished only by their meaning, we varied the semantic relationship between distractors and targets following at different lags. Semantic relatedness alone produced a classic attentional blink. We conclude by discussing how attention theory might best accommodate these new effects.     

Eye movements do not reflect retrieval processes: limits of the eye-mind hypothesis

Abstract— This research investigated whether eye movements are informative about retrieval processes. Participants learned facts about persons and locations, and the number of facts (fan) learned about each person and location was manipulated. During a subsequent recognition test, participants made more gazes to high-fan facts than to low-fan facts, and gazes to high-fan facts had a longer duration than gazes to low-fan facts. However, there was no relation between the order in which items were fixated and the relative effect of person or location fan. The effect of person and location fan on gaze duration also did not differ with whether it was the person or location being fixated. A model assuming that the process of retrieval is independent of eye movements was successfully fit to the data on the distribution of gaze durations. According to this model, the effect of fan on number of gazes and gaze duration is an artifact of the longer retrieval times for high-fan facts.     

An age-related deficit in prefrontal cortical function associated with refreshing information

Older adults are slower than young adults to think of an item they just saw, that is, to engage or execute (or both) the simple reflective operation of refreshing just-activated information. In addition, they derive less long-term memory benefit from refreshing information. Using functional magnetic resonance imaging (fMRI), we found that relative to young adults, older adults showed reduced refresh-related activity in an area of dorsolateral prefrontal cortex (left middle frontal gyrus, Brodmann's Area 9), but not in other refresh-related areas. This provides strong evidence that a frontal component of the circuit that subserves this basic cognitive process is especially vulnerable to aging. Such a refresh deficit could contribute to poorer performance of older than young adults on a wide range of cognitive tasks.     

Disclosure of HIV-Positive Status to Latino Gay Men's Social Networks

This study explored disclosure of serostatus in a sample of 155 HIV-positive Latino gay men from New York City and Washington, DC. We examined rates of disclosure to different members of the social network: mothers, fathers, close friends, and primary sexual partners. There were high rates of disclosure of HIV-positive serostatus to main partners and closest friends and lower rates to fathers and mothers. We examined the role of 3 contextual target-dependent factors (emotional closeness to target, anticipated reactions from target, and target's knowledge of sexual orientation), as well as acculturation and time since diagnosis. Three separate logistic regression models were performed to predict disclosure of HIV-positive status to 3 targets: mothers, fathers, and closest friends. We found that disclosure was not a generalized tendency, but rather different factors were influential depending on the target. Whether the target was aware of participant's sexual orientation was associated with disclosure in all 3 models. Greater emotional closeness also predicted disclosure to mother and father; greater U.S. acculturation was associated with disclosure to father and marginally to mother. A longer time since diagnosis was associated with disclosure to the closest friend. These findings highlight the importance of taking into account roles and relationships, and their effect on disclosure.     

Likelihood ratios: A simple and flexible statistic for empirical psychologists

Empirical studies in psychology typically employ null hypothesis significance testing to draw statistical inferences. We propose that likelihood ratios are a more straightforward alternative to this approach. Likelihood ratios provide a measure of the fit of two competing models; the statistic represents a direct comparison of the relative likelihood of the data, given the best fit of the two models. Likelihood ratios offer an intuitive, easily interpretable statistic that allows the researcher great flexibility in framing empirical arguments. In support of this position, we report the results of a survey of empirical articles in psychology, in which the common uses of statistics by empirical psychologists is examined. From the results of this survey, we show that likelihood ratios are able to serve all the important statistical needs of researchers in empirical psychology in a format that is more straightforward and easier to interpret than traditional inferential statistics.     

The neural bases of complex tool use in humans

The behaviors involved in complex human tool use cut across boundaries traditionally drawn between social, cognitive, perceptual and motor processes. Longstanding neuropsychological evidence suggests a distinction between brain systems responsible for representing: (1) semantic knowledge about familiar tools and their uses, and (2) the acquired skills necessary for performing these actions. Contemporary findings in functional neuroimaging support and refine this distinction by revealing the distributed neural systems that support these processes and the conditions under which they interact. Together, these findings indicate that behaviors associated with complex tool use arise from functionally specialized networks involving temporal, parietal and frontal areas within the left cerebral hemisphere.     

The relationship between reading ability and lateralized lexical decision

Although lexical decision remains one of the most extensively studied cognitive tasks, very little is known about its relationship to broader linguistic performance such as reading ability. In a correlational study, several aspects of lateralized lexical decision performance were related to vocabulary and reading comprehension measures, as assessed using the Nelson-Denny Reading Test. This lateralized lexical decision task has been previously shown to demonstrate (1) independent contributions from both hemispheres, as well as (2) interhemispheric interactions during word recognition. Lexical decision performance showed strong relationships with both reading measures. Specifically, vocabulary performance correlated significantly with left visual field (LVF) word accuracy and LVF non-word latency, both measures of right hemisphere performance. There were also significant, though somewhat weaker, correlations between reading comprehension and RVF non-word latency. Lexicality priming, a measure of interhemispheric communication during lexical decision, was also correlated with reading comprehension. These results suggest that hemispheric interaction during word recognition is common, and that lexical processing contribution from the right hemisphere, something commonly taken as minor and inconsequential, can lead to significant performance benefits and to individual differences in reading.     

The impact of frontal and non-frontal brain tumor lesions on Wisconsin Card Sorting Test performance

Several lesion and imaging studies have suggested that the Wisconsin Card Sorting Test (WCST) is a measure of executive dysfunction. However, some studies have reported that this measure has poor anatomical specificity because patients with either frontal or non-frontal focal lesions exhibit similar performance. This study examined 25 frontal, 20 non-frontal low-grade brain tumor patients, and 63 normal controls (NC) on the WCST. The frontal patients were also assigned to either a left frontal (n=10) group or a right frontal group (n=15) and compared with the non-frontal group and NC. It was hypothesized that the frontal brain tumor patients would display greater deficits on categories achieved and a higher number of perseverative errors than non-frontal brain tumor patients on the WCST. Finally, it was predicted that right frontal brain tumors would result in greater executive functioning deficits than left frontal or non-frontal brain tumors. Results indicated that the left frontal group achieved the fewest categories and committed the most perseverative errors compared to the other patient and normal control groups. In addition, the left frontal group committed significantly more perseverative errors than the right frontal group. These results suggest that the WCST is sensitive to the effects of low-grade brain tumors on executive functioning.