Do different tests of episodic memory produce consistent results in human adults?

A number of different philosophical, theoretical, and empirical perspectives on episodic memory have led to the development of very different tests with which to assess it. Although these tests putatively assess the same psychological capacity, they have rarely been directly compared. Here, a sample of undergraduates was tested on three different putative tests of episodic memory (What-Where-When, Unexpected Question/Source Memory, and Free Recall). It was predicted that to the extent to which these different tests are assessing the same psychological process, performance across the various tests should be positively correlated. It was found that not all tests were related and those relationships that did exist were not always linear. Instead, two tests showed a quadratic relationship, suggesting the contribution of multiple psychological processes. It is concluded that not all putative tests of episodic cognition are necessarily testing the same thing.We thank the research students who were involved in this project, Mathilda Hay and Stephanie Bailey. We also thank Netta Chachuma and Francesca Lewis for help on an early version of this study, and James Thom, Ljerka Ostojic, Jon Simons, and Tom Smulders for commenting on versions of the manuscript, and Daniel Booth and Anthony Cheke for proofreading. Special thanks to Chris Stephenson for creating, maintaining, and updating the computer-based task. L.G.C. was funded by an MRC doctoral training studentship, an MRC Centenary Early Career Award, and a Junior Research Fellowship at Girton College, Cambridge.This is the final version of the article. It first appeared from Cold Spring Harbor Laboratory Press via http://dx.doi.org/10.1101/lm.030502.11

The role of memory ability, depth and mode of recall in the impact of memory on later consumption.

It has been shown that recalling a meal eaten a few hours earlier (vs. the previous day) leads to reduced snacking ('meal-recall' effect). This study attempted to replicate this effect, by assessing participants' (N = 77, mean age = 33.30 [SD = 14.98], mean BMI = 23.77 [SD = 3.72], 74% female) biscuit consumption during a bogus taste test in two separate sessions, before which participants recalled a recent or a distant meal. It was explored whether factors that might affect the quality of a meal-memory, particularly individual differences in memory ability and depth of recall, would influence the meal-recall effect. To this end, only participants with a low or high memory ability were recruited for the study and were allocated to either an unguided-recall or guided-recall condition. In the unguided condition, participants were asked to recall what they ate, and in the guided condition they were prompted for further details regarding their meal. Participants were asked to either recall their meal out loud through an interview with the experimenter or by writing their recollection down on the computer. Contrary to the initial hypotheses, it was found that only the written group demonstrated the meal-recall effect, whereas the verbal group did not. Moreover, this was specific to the written, unguided group, in which participants ate about 9 g fewer biscuits after recalling a recent (vs. a distant) meal, F (1,15) = 6.07, p = .026, ηp2 = 0.288. The written, guided group's snacking seemed to increase by about 8 g after recalling a recent (vs. a distant) meal, F (1,20) = 7.31, p = .014, ηp2 = 0.268. The meal-recall effect was not evident in the verbal group. Memory ability did not influence the magnitude of the meal-recall effect. The results highlight the importance of contextual factors in modulating the meal-recall effect

The six blind men and the elephant: Are episodic memory tasks tests of different things or different tests of the same thing?

The development of episodic memory in children has been of interest to researchers for more than a century. Current behavioral tests that have been developed to assess episodic memory differ substantially in their surface features. Therefore, it is possible that these tests are assessing different memory processes. In this study, 106 children aged 3 to 6 years were tested on four putative tests of episodic memory. Covariation in performance was investigated in order to address two conflicting hypotheses: (a) that the high level of difference between the tests will result in little covariation in performance despite their being designed to assess the same ability and (b) that the conceptual similarity of these tasks will lead to high levels of covariation despite surface differences. The results indicated a gradual improvement with age on all tests. Performances on many of the tests were related, but not after controlling for age. A principal component analysis found that a single principal component was able to satisfactorily fit the observed data. This principal component produced a marginally stronger correlation with age than any test alone. As such, it might be concluded that different tests of episodic memory are too different to be used in parallel. Nevertheless, if used together, these tests may offer a robust assessment of episodic memory as a complex multifaceted process.Lucy Cheke was funded by a Medical Research Council (MRC) doctoral research fellowship and a Sarah Woodhead Research Fellowship at Girton College, Cambridge.This is the final published version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0022096515000661#

Episodic cognition: what is it, where is it, and when does it develop?

Episodic Cognition (or “Mental Time Travel”) is the ability to mentally re-experience events from our personal past and imagine potential events from our personal future. This capacity is fundamental to our lives and has been argued to be uniquely human. The aim of this thesis is to use behavioural tasks developed in comparative cognition to integrate both the literature on different research subjects (animals, children, adults, patients) but also from different theoretical perspectives, with the hope of facilitating communication and comparison between these fields. The backbone of the thesis is the behavioural tasks themselves, along with their origins in theory. Specifically, the “What-Where-When”, “Unexpected Question” and “Free Recall” episodic memory tasks and the “Bischof-Köhler” test of episodic foresight. Each of these tasks stems from different theoretical approaches to defining episodic cognition. Whilst extensively studied, these four tasks have never been undertaken by the same subjects and have never been directly compared. It is thus unclear whether these different theoretical perspectives converge on a single “episodic cognition” system, or a variety of overlapping processes. This thesis explores these issues by presenting these tasks to previously untested animal (the Eurasian Jay), developing children (aged 3-6), and a sample of human adults (Cambridge Undergraduates). Finally, these findings are applied in the assessment of episodic cognition in a population that is thought to have mild hippocampal damage – the overweight and obese. It was predicted that if all these putative tests of episodic cognition were tapping into the same underlying ability, then they should be passed by the same animal species, develop at the same time in children, correlate in human adults and be impaired in those with damage to the relevant brain areas. These predictions were, to some degree, confirmed. While the novel animal model could not be tested on all paradigms, the jays performed well on Bischof-Köhler future planning test. However, the results of the What-Where-When memory test were equivocal. There was a relatively low degree of correlation between performance on all the tasks in human children, along with a suggestion that each had a distinct developmental trajectory. The study of human adults revealed that while performance on all the tasks were related to one another, this relationship was often nonlinear, suggesting the contribution of several different psychological processes. Finally, it was found that both memory and performance on the Bischof-Köhler future planning task were altered in individuals who are overweight. A potentially surprising theme throughout the results is that performance on the Bischof-Köhler tasks is in fact negatively related to performance on memory tests, and improves in patients thought to have mild hippocampal damage. It is concluded that there may be a significant degree of overlap in the processes tapped by different putative tests of episodic memory, but that they can not be considered to be equivalent. Furthermore, it is suggested that episodic cognition is a fundamentally ineffective system with which to predict future motivational states, because it is biased by current feelings

What-where-when memory and encoding strategies in healthy aging.

Older adults exhibit disproportionate impairments in memory for item-associations. These impairments may stem from an inability to self-initiate deep encoding strategies. The present study investigates this using the "treasure-hunt task"; a what-where-when style episodic memory test that requires individuals to "hide" items around complex scenes. This task separately assesses memory for item, location, and temporal order, as well as bound what-where-when information. The results suggest that older adults are able to ameliorate integration memory deficits by using self-initiated encoding strategies when these are externally located and therefore place reduced demands on working memory and attentional resources.This study was funded by an MRC Centenary Early Career Fellowship and a Sarah Woodhead Fellowship from Girton College, Cambridge.This is the final version of the article. It first appeared from Cold Spring Harbor Laboratory Press via https://doi.org/10.1101/lm.040840.11

Exploring the relative contributions of reward-history and functionality information to children's acquisition of the Aesop's fable task.

Investigation of tool-using behaviours has long been a means by which to explore causal reasoning in children and nonhuman animals. Much of the recent research has focused on the "Aesop's Fable" paradigm, in which objects must be dropped into water to bring a floating reward within reach. An underlying problem with these, as with many causal reasoning studies, is that functionality information and reward history are confounded: a tool that is functionally useful is also rewarded, while a tool that is not functionally useful is not rewarded. It is therefore not possible to distinguish between behaviours motivated by functional understanding of the properties of the objects involved, and those influenced by reward-history. Here, we devised an adapted version of the Aesop's Fable paradigm which decouples functionality information and reward history by making use of situations in which the use of a particular tool should have enabled a subject to obtain (or not obtain) a reward, but the outcome was affected by the context. Children aged 4-11 were given experience of a range of tools that varied independently in whether they were functional or non-functional and rewarded or non-rewarded. They were then given the opportunity to choose which tools they would like to use in a test trial, thereby providing an assessment of whether they relied on information about functionality or the reward history associated with the object or a combination of the two. Children never significantly used reward history to drive their choices of tools, while the influence of functionality information increased with age, becoming dominant by age 7. However, not all children behaved in a consistent manner, and even by 10 years of age, only around a third exclusively used functionality as a basis for their decision-making. These findings suggest that from around the age of 7-years, children begin to emphasize functionality information when learning in novel situations, even if competing reward information is available, but that even in the oldest age-group, most children did not exclusively use functionality information

How do children solve Aesop's Fable?

Studies on members of the crow family using the "Aesop's Fable" paradigm have revealed remarkable abilities in these birds, and suggested a mechanism by which associative learning and folk physics may interact when learning new problems. In the present study, children between 4 and 10 years of age were tested on the same tasks as the birds. Overall the performance of the children between 5-7-years was similar to that of the birds, while children from 8-years were able to succeed in all tasks from the first trial. However the pattern of performance across tasks suggested that different learning mechanisms might be being employed by children than by adult birds. Specifically, it is possible that in children, unlike corvids, performance is not affected by counter-intuitive mechanism cues.This is the final version of the article. It first appeared from PLOS via http://dx.doi.org/10.1371/journal.pone.004057

Artificial Intelligence and the Common Sense of Animals

The problem of common sense remains a major obstacle to progress in artificial intelligence. Here, we argue that common sense in humans is founded on a set of basic capacities that are possessed by many other animals, capacities pertaining to the understanding of objects, space, and causality. The field of animal cognition has developed numerous experimental protocols for studying these capacities and, thanks to progress in deep reinforcement learning (RL), it is now possible to apply these methods directly to evaluate RL agents in 3D environments. Besides evaluation, the animal cognition literature offers a rich source of behavioural data, which can serve as inspiration for RL tasks and curricula

Episodic Memory Deficits in Obesity

Obesity has become an international health crisis. There is accumulating evidence that excess bodyweight is associated with changes to the structure and function of the brain and with a number of cognitive deficits. In particular, research suggests that obesity is associated with hippocampal and frontal lobe dysfunction, which would be predicted to impact memory. However, evidence for such memory impairment is currently limited. We hypothesised that higher body mass index (BMI) would be associated with reduced performance on a test of episodic memory that assesses not only content, but also context and feature integration. A total of 50 participants aged 18-35 years, with BMIs ranging from 18 to 51, were tested on a novel what-where-when style episodic memory test: the "Treasure-Hunt Task". This test requires recollection of object, location, and temporal order information within the same paradigm, as well as testing the ability to integrate these features into a single event recollection. Higher BMI was associated with significantly lower performance on the what-where-when (WWW) memory task and all individual elements: object identification, location memory, and temporal order memory. After controlling for age, sex, and years in education, the effect of BMI on the individual what, where, and when tasks remained, while the WWW dropped below significance. This finding of episodic memory deficits in obesity is of concern given the emerging evidence for a role for episodic cognition in appetite regulation.This study was funded by an MRC Centenary Early Career Award. LGC was funded by the Sarah Woodhead Research Fellowship at Girton College Cambridge. JSS was funded by a James S. McDonnell Foundation Scholar Award, and NSC was funded by an Experimental Psychology Society Mid Career Award

How does episodic memory develop in adolescence?

Key areas of the episodic memory (EM) network demonstrate changing structure and volume during adolescence. EM is multifaceted and yet studies of EM thus far have largely examined single components, used different methods and have unsurprisingly yielded inconsistent results. The Treasure Hunt task is a single paradigm that allows parallel investigation of memory content, associative structure, and the impact of different retrieval support. Combining the cognitive and neurobiological accounts, we hypothesized that some elements of EM performance may decline in late adolescence owing to considerable restructuring of the hippocampus at this time. Using the Treasure Hunt task, we examined EM performance in 80 participants aged 10-17 yr. Results demonstrated a cubic trajectory with youngest and oldest participants performing worst. This was emphasized in associative memory, which aligns well with existing literature indicating hippocampal restructuring in later adolescence. It is proposed that memory development may follow a nonlinear path as children approach adulthood, but that future work is required to confirm and extend the trends demonstrated in this study