Mechanisms of imagery-perception interaction

A number of different research findings have shown that mental imagery can affect the perceptual processing of stimuli. The present research was aimed at characterizing the representations and processes underlying imagery-perception interactions. In four experiments, subjects mentally projected images of letters into the visual field, and either detected or detected and localized point threshold stimuli that fell on or off the image. Stimuli falling on the image were detected more often than stimuli falling off the image, consistent with the hypothesis that the representations at the interface between imagery and perception have an array format. When the facilitation was analyzed in terms of signal detection theory, it was found to consist only of criterion lowering, and not of enhanced sensitivity. The local criterion-lowering effect of imaged letters was then compared with the effect of perceiving a letter and attending to a letter. Perceiving a letter had no discernible effect on stimulus detection, whereas attending to the letter caused the same local criterion lowering, without sensitivity changes, as imaging the letter. This is consistent with the claims of Neisser (1976) and others that imagery is an attentional state.     

Brain-behavior relationships in reading acquisition are modulated by socioeconomic factors

Functional neuroimaging may provide insights into the achievement gap in reading skill commonly observed across socioeconomic status (SES). Brain activation during reading tasks is known to be associated with individual differences in children's phonological language skills. By selecting children of equivalent phonological skill, yet diverse socioeconomic backgrounds, we use functional magnetic resonance imaging (fMRI) to demonstrate that a child's experience, as operationalized by SES, can systematically modulate the relationship between phonological language skills and reading-related brain activity in left fusiform and perisylvian regions. Specifically, at lower socioeconomic levels, individual differences in skill result in large differences in brain activation. In contrast, as SES increases, this relationship between phonological language skill and activation is attenuated. Socioeconomic background factors are thus found to modulate brain-behavior relationships in reading, indicating that cognitive, social, and neurobiological influences on reading development are fundamentally intertwined.     

Empathy deficits and trait emotional intelligence in psychopathy and Machiavellianism

This study investigated the relationships between psychopathy (primary and secondary), Machiavellianism, trait emotional intelligence and empathy, using an image task that required an appropriate empathic response to the emotional displays of others (happy, sad and neutral). Results indicated that primary psychopathy and Machiavellianism were positively associated with the experience of positive affect from sad stimuli, while secondary psychopathy and Machiavellianism were positively associated with the experience of negative affect in response to neutral stimuli, and the opposite pattern was found for trait emotional intelligence. Regressional analyses demonstrated that secondary psychopathy, Machiavellianism, trait emotional intelligence and state anxiety are important predictors when stimuli are ambiguous.     

Superadditive effects of multiple lesions in a connectionist architecture: implications for the neuropsychology of optic aphasia

Neuropsychological disorders have traditionally been understood in terms of a focal lesion to a single component of a cognitive architecture. Optic aphasia (OA) defies explanation in this way. In OA, naming of visual stimuli is impaired in the absence of general visual agnosia or anomia. OA has been explained by positing multiple semantic systems or multiple functional pathways to visual naming. M. J. Farah (1990) instead sketched a parsimonious account based on multiple lesions--to pathways mapping visual input to semantic and semantics to naming responses--and the assumption that the effects of the lesions are superadditive. The authors demonstrate superadditive effects of damage in a connectionist architecture and model other phenomena associated with OA. Multiple lesions with superadditivity provide a novel class of explanations for neuropsychological deficits that previously seemed to imply the existence of highly specialized processing components.     

Mental rotation: An event-related potential study with a validated mental rotation task

Event-related potentials (ERPs) were recorded while subjects performed a validated mental rotation task, taken from the cognitive psychology literature. These ERPs show a late posterior negativity relative to a baseline condition requiring all of the same perceptual and cognitive processes except for the mental rotation itself. Our tentative identification of this posterior negativity with mental rotation is further supported by the finding that it varies systematically with the amount of mental rotation required on a trial by trial basis in the experimental task. We conclude that this late negativity is an ERP marker of the mental rotation process, and that this process engages primarily posterior brain regions.