Effects of aging and IQ on item and associative memory.
ABSTRACT: The effects of aging and IQ on performance were examined in 4 memory tasks: item recognition, associative recognition, cued recall, and free recall. For item and associative recognition, accuracy and the response time (RT) distributions for correct and error responses were explained by Ratcliff's (1978) diffusion model at the level of individual participants. The values of the components of processing identified by the model for the recognition tasks, as well as accuracy for cued and free recall, were compared across levels of IQ (ranging from 85 to 140) and age (college age, 60-74 years old, and 75-90 years old). IQ had large effects on drift rate in recognition and recall performance, except for the oldest participants with some measures near floor. Drift rates in the recognition tasks, accuracy in recall, and IQ all correlated strongly. However, there was a small decline in drift rates for item recognition and a large decline for associative recognition and cued recall accuracy (70%). In contrast, there were large effects of age on boundary separation and nondecision time (which correlated across tasks) but small effects of IQ. The implications of these results for single- and dual-process models of item recognition are discussed, and it is concluded that models that deal with both RTs and accuracy are subject to many more constraints than are models that deal with only one of these measures. Overall, the results of the study show a complicated but interpretable pattern of interactions that present important targets for modeling.
Project description:Item and associative recognition for pictures and words with college-age young adults and 60-75-year-old adults were examined in the experiment reported in this article. The diffusion model (Ratcliff & McKoon, 2008) was used to extract estimates of components of processing from the empirical values of accuracy and correct and error response time distributions. The model fit the empirical data well for both picture and word stimuli. Results showed that boundary separation was larger and nondecision time was longer for older relative to young adults. Drift rates were not lower for older adults for item recognition but they were for associative recognition, indicating that the richer structure of pictures did not provide an enhanced ability to form associations for the older adults. There were also significant correlations among the components of processing across the tasks of the experiment, suggesting common factors, but participants' accuracy and response times did not significantly correlate within and across the tasks.
Project description:Associative memory is one of the first cognitive functions negatively affected by healthy and pathological aging processes. Non-invasive brain stimulation (NIBS) techniques are easily administrable tools to support memory. However, the optimal stimulation parameters inducing a reliable positive effect on older adult's memory performance remain mostly unclear. In our randomized, double-blind, cross-over study, 28 healthy older adults (16 females; 71.18 + 6.42 years of age) received anodal transcranial direct (tDCS), alternating current in the theta range (tACS), and sham stimulation over the left ventrolateral prefrontal cortex (VLPFC) each once during encoding. We tested associative memory performance with cued recall and recognition tasks after a retention period and again on the following day. Overall, neither tDCS nor tACS showed effects on associative memory performance. Further analysis revealed a significant difference for performance on the cued recall task under tACS compared to sham when accounting for age. Our results suggest that tACS might be more effective to improve associative memory performance than tDCS in higher aged samples.
Project description:Cognitive impairment is a hallmark of schizophrenia; however, studies have not comprehensively examined such impairments in non-clinically ascertained schizotypic young adults. The present study employed a series of measures to assess episodic memory in high positive schizotypy, high negative schizotypy, and comparison groups (each group n = 25). Consistent with diminished cognitive functioning seen in negative symptom schizophrenia, the negative schizotypy group exhibited deficits on free recall, recognition, and source memory tasks. The positive schizotypy group did not demonstrate deficits on the above mentioned tasks. However, in contrast to the other groups, the positive schizotypy group showed an unexpected set-size effect on the cued-recall task. Set-size effect, which refers to the finding that words that have smaller networks of associates tend to have a memory advantage, is usually found in associative-cuing, but not cued-recall, tasks. The finding for the positive schizotypy group is consistent with heightened spreading activation and reduced executive control suggested to underlie psychotic symptoms. The findings support a multidimensional model of schizotypy and schizophrenia, and suggest that positive and negative schizotypy involve differential patterns of cognitive impairment.
Project description:We present findings of a novel and ecologically relevant associative memory test, the Object Location Touchscreen Test (OLTT), which was posited as sensitive to early medial temporal lobe compromise associated with mild cognitive impairment (MCI).A total of 114 participants, including healthy young and older controls and patients with MCI, completed the OLTT and standard neuropsychological testing. The OLTT required participants to recall the location of objects under free and cued recall conditions, with accuracy evaluated using distance measures (i.e., a continuous error score), and a standard recognition format. Correlations between performance and volumetric data were evaluated from a subset of 77 participants.Significant age effects were dwarfed by MCI effects across all test conditions. OLTT Cued Recall was strongly and specifically related to the volume of disease-relevant medial temporal lobe regions, generally more than traditional memory tests.The OLTT may be sensitive to early structural compromise in regions affected by Alzheimer's disease.
Project description:We tested the hypothesis that the feeling of knowing (FOK) after a failed recall attempt is influenced by recalling aspects of the original encoding strategy. Individuals were instructed to use interactive imagery to encode unrelated word pairs. We manipulated item concreteness (abstract vs. concrete) and item repetitions at study (one vs. three). Participants orally described the mediator produced immediately after studying each item, if any. After a delay, they were given cued recall, made FOK ratings, and attempted to recall their original mediator. Concreteness and item repetition enhanced strategy recall, which had a large effect on FOKs. Controlling on strategy recall reduced the predictive validity of FOKs for recognition memory, indicating that access to the original aspects of encoding influenced FOK accuracy. Confidence judgments (CJs) for correctly recognized items covaried with FOKs, but FOKs did not fully track the strategy recall associations with CJs, suggesting emergent effects of strategy cues that were elicited by recognition tests but not accessed at the time of the FOK judgment. In summary, cue-generated access to aspects of the original encoding strategy strongly influenced episodic FOKs, although other influences were also implicated.
Project description:Recent studies have demonstrated that memory performance can be enhanced by a cue which indicates the item most likely to be subsequently probed, even when that cue is delivered seconds after a stimulus array is extinguished. Although such retro-cuing has attracted considerable interest, the mechanisms underlying it remain unclear. Here, we tested the hypothesis that retro-cues might protect an item from degradation over time. We employed two techniques that previously have not been deployed in retro-cuing tasks. First, we used a sensitive, continuous scale for reporting the orientation of a memorized item, rather than binary measures (change or no change) typically used in previous studies. Second, to investigate the stability of memory across time, we also systematically varied the duration between the retro-cue and report. Although accuracy of reporting uncued objects rapidly declined over short intervals, retro-cued items were significantly more stable, showing negligible decline in accuracy across time and protection from forgetting. Retro-cuing an object's color was just as advantageous as spatial retro-cues. These findings demonstrate that during maintenance, even when items are no longer visible, attention resources can be selectively redeployed to protect the accuracy with which a cued item can be recalled over time, but with a corresponding cost in recall for uncued items.
Project description:Although negative emotion can strengthen memory of an event it can also result in memory disturbances, as in post-traumatic stress disorder (PTSD). We examined the effects of negative item content on amygdalar and hippocampal function in memory for the items themselves and for the associations between them. During fMRI, we examined encoding and retrieval of paired associates made up of all four combinations of neutral and negative images. At test, participants were cued with an image and, if recognised, had to retrieve the associated (target) image. The presence of negative images increased item memory but reduced associative memory. At encoding, subsequent item recognition correlated with amygdala activity, while subsequent associative memory correlated with hippocampal activity. Hippocampal activity was reduced by the presence of negative images, during encoding and correct associative retrieval. In contrast, amygdala activity increased for correctly retrieved negative images, even when cued by a neutral image. Our findings support a dual representation account, whereby negative emotion up-regulates the amygdala to strengthen item memory but down-regulates the hippocampus to weaken associative representations. These results have implications for the development and treatment of clinical disorders in which diminished associations between emotional stimuli and their context contribute to negative symptoms, as in PTSD.
Project description:The role of the hippocampus in recollection and familiarity remains debated. Using functional magnetic resonance imaging (fMRI), we explored whether hippocampal activity is modulated by increasing recollection confidence, increasing amount of recalled information, or both. We also investigated whether any hippocampal differences between recollection and familiarity relate to processing differences or amount of information in memory. Across two fMRI tasks, we separately compared brain responses to levels of confidence for cued word recall and word familiarity, respectively. Contrary to previous beliefs, increasing confidence/accuracy of cued recall of studied words did not increase hippocampal activity, when unconfounded by amount recollected. In contrast, additional recollection (i.e., recollecting more information than the word alone) increased hippocampal activity, although its accuracy matched that of word recall alone. Unlike cued word recall, increasing word familiarity accuracy did increase hippocampal activity linearly, although at an uncorrected level. This finding occurred although cued word recall and familiarity memory seemed matched with respect to information in memory. The detailed characteristics of these effects do not prove that word familiarity is exceptional in having hippocampal neural correlates. They suggest instead that participants fail to identify some aspects of recollection, misreporting it as familiarity, a problem with word-like items that have strong and recallable semantic associates.
Project description:Enhanced emotional memory often comes at the cost of memory for surrounding background information. Narrowed-encoding theories suggest that this is due to narrowed attention for emotional information at encoding, leading to impaired encoding of background information. Recent work has suggested that an encoding-based theory may be insufficient. Here, we examined whether cued recall-instead of previously used recognition memory tasks-would reveal evidence that non-emotional information associated with emotional information was effectively encoded. Participants encoded positive, negative, or neutral objects on neutral backgrounds. At retrieval, they were given either the item or the background as a memory cue and were asked to recall the associated scene element. Counter to narrowed-encoding theories, emotional items were more likely than neutral items to trigger recall of the associated background. This finding suggests that there is a memory trace of this contextual information and that emotional cues may facilitate retrieval of this information.
Project description:Research suggests that metacognitive monitoring ability does not decline with age. For example, judgments-of-learning (JOL) accuracy is roughly equivalent between younger and older adults. But few studies have asked whether younger and older adults' metacognitive ability varies across different types of memory processes (e.g., for items vs. pairs). The current study tested the relationship between memory and post-decision confidence ratings at the trial level on item (individual words) and associative (word pairs) memory recognition tests. As predicted, younger and older adults had similar <i>metacognitive efficiency</i>, when using meta-<i>d'/d'</i>, a measure derived from Signal Detection Theory, despite a significant age effect favoring younger adults on memory performance. This result is consistent with previous work showing age-equivalent metacognitive efficiency in the memory domain. We also found that metacognitive efficiency was higher for associative memory than for item memory across age groups, even though associative and item recognition memory (<i>d'</i>) were statistically equivalent. Higher accuracy on post-test decision confidence ratings for associative recognition relative to item recognition on resolution accuracy itself (meta-<i>d'</i>) and when corrected for performance differences (meta-<i>d'/d'</i>) are novel findings. Implications for associative metacognition are discussed.