Dissociating Confidence and Accuracy: Functional Magnetic Resonance Imaging Shows Origins of the Subjective Memory Experience

Successful memory typically implies both objective accuracy and subjective confidence, but there are instances when confidence and accuracy diverge. This dissociation suggests that there may be distinct neural patterns of activation related to confidence and accuracy. We used event-related functional magnetic resonance imaging to study the encoding of novel face–name associations, assessed with a postscan memory test that included objective measures of accuracy and subjective measures of confidence. We showed specific neural activity in the left inferior prefrontal cortex associated with trials when subjects expressed high confidence that they had chosen the correct name for the face and made a correct identification. Moreover, we found that this region was also associated with imparting high confidence when subjects chose the incorrect name. However, medial temporal lobe regions showed activity only for high-confidence correct trials. Many functional magnetic resonance imaging studies have shown that the medial temporal lobe and left prefrontal regions are particularly important for the successful formation of memories by using a combination of subjective and objective measures. Our findings suggest that these regions may be differentially involved in the objective and subjective components of memory and that the origins of confidence–accuracy dissociations may be related to incomplete activation of the neural pattern seen in successful encoding. These findings may also aid understanding of eyewitness misidentifications and memory distortions.Psycholog

Measurement of informal caregiving to older disabled adults in the United States

Objectives. (1) To describe the methodology used to measure informal caregiving in national population-based surveys. (2) To evaluate the influence of survey design on the estimated number and characteristics of caregivers in the US. (3) To compare the characteristics of caregivers and their care-recipients across primacy status. Methods. A detailed review of national population based surveys of aging and caregiving was conducted to identify the key elements of variation in the measurement of caregiving. Two elements identified as possible sources of variation, survey sample frame and primacy status of caregivers included in the sample, were then explored analytically. The influence of sample frame on the number and characteristics of caregivers and care-recipients was examined by applying a single rigorous definition of caregiving to the 2004 Health and Retirement Survey (HRS) and 2004 Survey of Income and Program Participation (SIPP). The influence of primacy status of caregivers was explored by comparing primary and secondary caregivers and their care-recipients in the 2004 HRS using logistic regression corrected for complex survey design. Results. The weighted number of caregivers was not found to differ between the HRS and SIPP; the prevalence of disability was significantly greater in the HRS and the prevalence of receiving help was significantly greater in the SIPP. Other significant differences between the HRS and SIPP included the proportion of caregivers who were spouses, co-residing, and the proportion of care-recipients of lower socio-economic status. Comparison of primary and secondary caregivers suggested that men were more likely to assume the role of secondary caregivers than women, and that non-white older disabled adults were more likely to have multiple caregivers than white older disabled adults. Conclusions. These data suggests that both sample frame and the operational definition of caregiving have a significant influence on both the estimated size and composition of the caregiving population identified in nation surveys. Policy makers who use estimates of caregiving from national health surveys may want to consider how the methods for identifying caregivers and disabled care-recipients affect our understanding of how many caregivers are available to provide care and at what cost