Effects of time of day on age-related associative deficits

Time of day is known to influence cognition differently across age groups, with young adults performing better later than earlier in the day and older adults showing the opposite pattern. Thus age-related deficits can be smaller when testing occurs in the morning compared with the afternoon/evening, particularly for tasks requiring executive/controlled/inhibitory processes. Stronger influences of time of day were therefore predicted on associative than on item recognition memory based on their differential requirements for demanding recollective (rather than familiarity) processes. In two experiments, participants were presented with unrelated word pairs and then tested on both item recognition (old/new item?) and associative recognition (intact/recombined pair?). In Experiment 1, young adults were tested either in the morning or in the evening; recognition memory was better when time of testing matched participants’ morningness-eveningness preferences, and more so for associative than for item memory. In Experiment 2, young and older adults (evening and morning types, respectively) were tested both in the morning and in the evening; again, recognition memory was better at participants’ preferred times of day, especially for associative memory. Consequently, age-related associative deficits varied considerably - indeed more than fourfold - from a nonsignificant 8% for testing in the morning to a substantial 35% for testing in the evening, suggesting that it is important to consider time of day effects in future studies of the associative deficit hypothesis

Deficits in category learning in older adults: rule-based versus clustering accounts

Memory research has long been one of the key areas of investigation for cognitive aging researchers but only in the last decade or so has categorization been used to understand age differences in cognition. Categorization tasks focus more heavily on the grouping and organization of items in memory, and often on the process of learning relationships through trial and error. Categorization studies allow researchers to more accurately characterize age differences in cognition: whether older adults show declines in the way in which they represent categories with simple rules or declines in representing categories by similarity to past examples. In the current study, young and older adults participated in a set of classic category learning problems, which allowed us to distinguish between three hypotheses: (i) rule-complexity: categories were represented exclusively with rules and older adults had differential difficulty when more complex rules were required, (ii) rule-specific: categories could be represented either by rules or by similarity, and there were age deficits in using rules, and (iii) clustering: similarity was mainly used and older adults constructed a less-detailed representation by lumping more items into fewer clusters. The ordinal levels of performance across different conditions argued against rule-complexity, as older adults showed greater deficits on less complex categories. The data also provided evidence against rule-specificity, as single-dimensional rules could not explain age declines. Instead, computational modelling of the data indicated that older adults utilized fewer conceptual clusters of items in memory than did young adults

Word frequency influences on the list length effect and associative memory in young and older adults

Many studies show that age deficits in memory are smaller for information supported by pre-experimental experience. Many studies also find dissociations in memory tasks between words that occur with high and low frequencies in language, but the literature is mixed regarding the extent of word frequency effects in normal ageing. We examined whether age deficits in episodic memory could be influenced by manipulations of word frequency. In Experiment 1, young and older adults studied short and long lists of high- and low-frequency words for free recall. The list length effect (the drop in proportion recalled for longer lists) was larger in young compared to older adults and for high- compared to low-frequency words. In Experiment 2, young and older adults completed item and associative recognition memory tests with high- and low-frequency words. Age deficits were greater for associative memory than for item memory, demonstrating an age-related associative deficit. High-frequency words led to better associative memory performance whilst low-frequency words resulted in better item memory performance. In neither experiment was there any evidence for age deficits to be smaller for high- relative to low-frequency words, suggesting that word frequency effects on memory operate independently from effects due to cognitive ageing

Influences of complexity on decision making in young and older adults

Leading theory hypothesizes that age deficits in decision making may rise as the complexity of decision-related information increases. This suggests that older adults would benefit relative to young adults from simplification of information used to inform decision making. Participants indicated political, nutritional and medical preferences and then chose between politicians, foods and medicines. The amount of information presented was systematically varied but age differences were largely similar for simple and complex trials. Paradoxically, the data showed that decisions based on simpler information could be less aligned with participant’s preferences than decisions based on more complex information. Further analyses suggested that participants may have been responding purely on the basis of their most valued preferences and that when information about those preferences was not presented, decision making became poorer. Contrary to our expectations, simplification of information by exclusion may therefore hinder decision making and may not particularly help older adults

When does prior knowledge disproportionately benefit older adults' memory?

Material consistent with knowledge/experience is generally more memorable than material inconsistent with knowledge/experience – an effect that can be more extreme in older adults. Four experiments investigated knowledge effects on memory with young and older adults. Memory for familiar and unfamiliar proverbs (Experiment 1) and for common and uncommon scenes (Experiment 2) showed similar knowledge effects across age groups. Memory for person-consistent and person-neutral actions (Experiment 3) showed a greater benefit of prior knowledge in older adults. For cued recall of related and unrelated word pairs (Experiment 4), older adults benefited more from prior knowledge only when it provided uniquely useful additional information beyond the episodic association itself. The current data and literature suggest that prior knowledge has the age-dissociable mnemonic properties of (1) improving memory for the episodes themselves (age invariant), and (2) providing conceptual information about the tasks/stimuli extrinsically to the actual episodic memory (particularly aiding older adults)

Homogeneity of memory errors in abstract visual pattern recall

In memory tests, recalled information can be distorted by errors in memory and these distortions can be more memorable than the original stimuli to a later learner. This is typically observed over several generations of learners but there is less exploration of the initial distortions from the first generation of learners. In this article, participants studied visual matrix patterns which were either erroneous recall attempts from previous participants or were random patterns. Experiment 1 showed some evidence that material based on previous participants’ recall data was more memorable than random material, but this did not replicate in Experiment 2. Of greater interest in the current data were homogeneity in the memory errors made by participants which demonstrated systematic recall biases in a single generation of learners. Unlike studies utilising multiple generations of learners, the currently observed distortions cannot be attributed to survival-of-the-fittest mechanisms where biases are driven by encoding effects

What you know can influence what you are going to know (especially for older adults)

Stimuli related to an individual's knowledge/experience are often more memorable than abstract stimuli, particularly for older adults. This has been found when material that is congruent with knowledge is contrasted with material that is incongruent with knowledge, but there is little research on a possible graded effect of congruency. The present study manipulated the degree of congruency of study material with participants’ knowledge. Young and older participants associated two famous names to nonfamous faces, where the similarity between the nonfamous faces and the real famous individuals varied. These associations were incrementally easier to remember as the name-face combinations became more congruent with prior knowledge, demonstrating a graded congruency effect, as opposed to an effect based simply on the presence or absence of associations to prior knowledge. Older adults tended to show greater susceptibility to the effect than young adults, with a significant age difference for extreme stimuli, in line with previous literature showing that schematic support in memory tasks particularly benefits older adults

Does audio-visual information result in improved health-related decision-making compared with audio-only or visual-only information? Protocol for a systematic review and meta-analysis

Introduction: Making health-related decisions can be difficult due to the amount and complexity of information available. Audio-visual information may improve memory for health information but whether audio-visual information can enhance health-related decisions has not been explored using quantitative methods. The objective of this systematic review is to understand how effective audio-visual information is for informing health-related decision-making compared with audio-only or visual-only information. Methods and analysis: Randomised controlled trials (RCTs) will be included if they include audio-visual and either audio-only or visual-only information provision and decision-making in a health setting. Studies will be excluded if they are not reported in English. Twelve databases will be searched including: Ovid MEDLINE, PubMed and PsychINFO. The Cochrane Risk of Bias tool (V.7) will be used to assess risk of bias in included RCTs. Results will be synthesised primarily using a meta-analysis; where quantitative data are not reported, a narrative synthesis will be used. Ethics and dissemination: No ethical issues are foreseen. Data will be disseminated via academic publication and conference presentations. Findings may also be published in scientific newsletters and magazines. This review is funded by the Economic and Social Research Council

Epigenetic Factors in Cancer Risk: Effect of Chemical Carcinogens on Global DNA Methylation Pattern in Human TK6 Cells

In the current study, we assessed the global DNA methylation changes in human lymphoblastoid (TK6) cells in vitro in response to 5 direct and 10 indirect-acting genotoxic agents. TK6 cells were exposed to the selected agents for 24 h in the presence and/or absence of S9 metabolic mix. Liquid chromatography-mass spectrometry was used for quantitative profiling of 5-methyl-2′-deoxycytidine. The effect of exposure on 5-methyl-2′-deoxycytidine between control and exposed cultures was assessed by applying the marginal model with correlated residuals on % global DNA methylation data. We reported the induction of global DNA hypomethylation in TK6 cells in response to S9 metabolic mix, under the current experimental settings. Benzene, hydroquinone, styrene, carbon tetrachloride and trichloroethylene induced global DNA hypomethylation in TK6 cells. Furthermore, we showed that dose did not have an effect on global DNA methylation in TK6 cells. In conclusion we report changes in global DNA methylation as an early event in response to agents traditionally considered as genotoxic