Neuropsychology of self-awareness in young adults.

Disorders of self-awareness are common following cortical damage, particularly to the frontal lobes, but there have been few studies of individual differences in self-awareness in the normal population. In the current study, we explored patterns of metacognitive awareness among healthy young adults, based on discrepancies of self- and other-ratings on the Frontal Systems Behavior Scale (FrSBe; Grace and Malloy, 2002). Those who showed poor metacognitive awareness showed more frequent lapses of attention, and higher levels of everyday absentmindedness, than those who accurately appraised their own behavior or those who overestimated their own FrSBe scores. Furthermore, among those with poor metacognitive awareness, online emergent awareness correlated positively with prospective memory performance, and negatively with anxiety scores. Our results suggest that accurate self-awareness in non-neurological participants relies on efficient sustained attention functioning, supporting the role of frontal control systems in neuroanatomical models of self-awareness.

Sustained attention in traumatic brain injury (TBI) and healthy controls: enhanced sensitivity with dual-task load.

Poor sustained attention or alertness is a common consequence of traumatic brain injury (TBI) and has a considerable impact on the recovery and adjustment of TBI patients. Here, we describe the development of a sensitive laboratory task in healthy subjects (Experiment 1) and its enhanced sensitivity to sustained attention errors in TBI patients (Experiment 2). The task involves withholding a key press to an infrequent no-go target embedded within a predictable sequence of numbers (primary goal) and detecting grey-coloured targets within the sequence (secondary goal). In Experiment 1, we report that neurologically healthy subjects are more likely to experience a lapse of attention and neglect the primary task goal, despite ceiling performance on the secondary task. Further, attentional lapses on the task correlated with everyday attentional failures and variability of response time. In Experiment 2, the task discriminates between TBI patients and controls with a large effect size. The dual-task yields more errors in both groups than a simple task involving only the primary goal that is commonly used to detect sustained attention deficits in neurologically impaired groups. TBI patients' errors also correlated with everyday cognitive failures and variability of response time. This was not the case in the simple version of the task. We conclude that the dual-task demand associated with this task enhances its sensitivity as a measure of sustained attention in TBI patients and neurologically healthy controls that relates to everyday slips of attention.

Capture by misleading information and its false acceptance in patients with traumatic brain injury.

Exposure to misleading information, presented after a critical episode, can alter or impair memory reports about that episode. Here, we examine vulnerability to misleading information in patients with traumatic brain injury (TBI). The ability to initiate an effective retrieval strategy and inhibit irrelevant or interfering information requires participation from the prefrontal cortices, which are susceptible to damage following brain injury. We report that TBI patients are more prone to interference effects produced by misleading information during a cued-recall task and are more likely to accept this information as the product of 'remembering' compared with healthy controls. The results are consistent with a model proposing that patients are captured by highly accessible responses eliminating their opportunity to engage in recollection. Correlations between the cued-recall interference task and other executive measures helped elucidate the processes underlying 'capture'. In TBI patients, reduced recollection produced by a misleading prime was associated with impaired prospective remembering when engaged in a background task. A common functional deficit that may underlie poor performance on both tasks is the failure to inhibit previously relevant but currently irrelevant information. Subjective reports pertaining to the subject's cued-recall response were indexed by electrodermal activity. In control subjects, larger skin conductance responses (SCRs) were associated with a greater frequency of guess reports, suggesting that SCRs provide a marker for uncertainty regarding the candidacy of a selected response. TBI patients did not show this relationship, suggesting that impairments of post-retrieval evaluation might also underlie greater false acceptance of misinformation. Discussion focuses on the role of the prefrontal cortex and cognitive processes that mediate the selection and evaluation of memories.

Poor insight in traumatic brain injury mediated by impaired error processing? Evidence from electrodermal activity.

Impaired deficit awareness is common following traumatic brain injury (TBI) and is a major obstacle to rehabilitation. We have previously confirmed the presence of impaired error awareness in TBI using a highly discriminating go/no-go procedure. In the present study, we extend this work to try to identify more closely the nature of the error awareness deficit using measures of electrodermal activity (EDA). Sixteen participants with TBI and sixteen age-, sex-, and education-matched controls performed the Sustained Attention to Response Task (SART), while EDA was recorded. TBI detected significantly fewer errors compared to controls. EDA was significantly attenuated for TBI participants even to errors of which they were aware; error detection rates and EDA amplitude were also correlated. These findings suggest that poor insight following TBI may result, in part, from impaired error processing abilities.