Rate of forgetting is independent from initial degree of learning across different age groups.

It is well established that the more we learn, the more we remember. It is also known that our ability to acquire new information changes with age. An important remaining issue for debate is whether the rate of forgetting depends on initial degree of learning. In two experiments, following the procedure used by Slamecka and McElree (Exp 3), we investigated the relationship between initial degree of learning and rate of forgetting in both younger and older adults. A set of 36 (Exp 1) and a set of 30 (Exp 2) sentences was presented four times. Forgetting was measured via cued recall at three retention intervals (30 s, 1 hr, and 24 hr). A different third of the original sentences was tested at each delay. The results of both experiments showed that initial acquisition is influenced by age. However, the rate of forgetting proved to be independent from initial degree of learning. The conclusion is that rates of forgetting are independent from initial degree of learning.

Preserved Extra-Foveal Processing of Object Semantics in Alzheimer's Disease.

Alzheimer's disease (AD) patients underperform on a range of tasks requiring semantic processing, but it is unclear whether this impairment is due to a generalised loss of semantic knowledge or to issues in accessing and selecting such information from memory. The objective of this eye-tracking visual search study was to determine whether semantic expectancy mechanisms known to support object recognition in healthy adults are preserved in AD patients. Furthermore, as AD patients are often reported to be impaired in accessing information in extra-foveal vision, we investigated whether that was also the case in our study. Twenty AD patients and 20 age-matched controls searched for a target object among an array of distractors presented extra-foveally. The distractors were either semantically related or unrelated to the target (e.g., a car in an array with other vehicles or kitchen items). Results showed that semantically related objects were detected with more difficulty than semantically unrelated objects by both groups, but more markedly by the AD group. Participants looked earlier and for longer at the critical objects when these were semantically unrelated to the distractors. Our findings show that AD patients can process the semantics of objects and access it in extra-foveal vision. This suggests that their impairments in semantic processing may reflect difficulties in accessing semantic information rather than a generalised loss of semantic memory.

Eye-movements reveal semantic interference effects during the encoding of naturalistic scenes in long-term memory.

Similarity-based semantic interference (SI) hinders memory recognition. Within long-term visual memory paradigms, the more scenes (or objects) from the same semantic category are viewed, the harder it is to recognize each individual instance. A growing body of evidence shows that overt attention is intimately linked to memory. However, it is yet to be understood whether SI mediates overt attention during scene encoding, and so explain its detrimental impact on recognition memory. In the current experiment, participants watched 372 photographs belonging to different semantic categories (e.g., a kitchen) with different frequency (4, 20, 40 or 60 images), while being eye-tracked. After 10 minutes, they were presented with the same 372 photographs plus 372 new photographs and asked whether they recognized (or not) each photo (i.e., old/new paradigm). We found that the more the SI, the poorer the recognition performance, especially for old scenes of which memory representations existed. Scenes more widely explored were better recognized, but for increasing SI, participants focused on more local regions of the scene in search for its potentially distinctive details. Attending to the centre of the display, or to scene regions rich in low-level saliency was detrimental to recognition accuracy, and as SI increased participants were more likely to rely on visual saliency. The complexity of maintaining faithful memory representations for increasing SI also manifested in longer fixation durations; in fact, a more successful encoding was also associated with shorter fixations. Our study highlights the interdependence between attention and memory during high-level processing of semantic information.

Alzheimer's Disease and Parkinson Dementia Distinguished by Cognitive Marker.

BACKGROUND: Temporary memory binding (TMB) has been shown to be specifically affected by Alzheimer's disease (AD) when it is assessed via free recall and titrating the task demands to equate baseline performance across patients. METHODS: Patients with Parkinson's disease (PD) were subdivided into patients with and without cognitive impairment and compared with AD and amnestic mild cognitive impairment (aMCI) patients on their performance on the TMB. RESULTS: The results show that only patients with AD dementia present with impaired TMB performance. Receiver operating characteristic curve analyses showed that TMB holds high sensitivity and specificity for aMCI and AD relative to PD groups and healthy controls. CONCLUSION: The TMB is sensitive to the neurodegenerative mechanisms leading to AD dementia but not to those underpinning PD dementia. As such, TMB task can aid the differential diagnosis of these common forms of dementia.

Extra-foveal Processing of Object Semantics Guides Early Overt Attention During Visual Search.

Eye-tracking studies using arrays of objects have demonstrated that some high-level processing of object semantics can occur in extra-foveal vision, but its role on the allocation of early overt attention is still unclear. This eye-tracking visual search study contributes novel findings by examining the role of object-to-object semantic relatedness and visual saliency on search responses and eye-movement behaviour across arrays of increasing size (3, 5, 7). Our data show that a critical object was looked at earlier and for longer when it was semantically unrelated than related to the other objects in the display, both when it was the search target (target-present trials) and when it was a target's semantically related competitor (target-absent trials). Semantic relatedness effects manifested already during the very first fixation after array onset, were consistently found for increasing set sizes, and were independent of low-level visual saliency, which did not play any role. We conclude that object semantics can be extracted early in extra-foveal vision and capture overt attention from the very first fixation. These findings pose a challenge to models of visual attention which assume that overt attention is guided by the visual appearance of stimuli, rather than by their semantics.

Theory of mind and the Ultimatum Game in healthy adult aging.

BACKGROUND: The Ultimatum Game assesses decision-making involved in cooperative interactions with others. However, little is known about the role that the ability to understand other people's intentions plays in these interactions. METHODS: This study examined performance on the Ultimatum Game and theory of mind (ToM) tasks in younger and older adults. RESULTS: Age differences were not found on the ToM tasks, and a lack of variability in performance prevented analyses of the relationships between performance on the Ultimatum Game and ToM. However, age differences were found on the Ultimatum Game, with older adults accepting more unfair offers. Yet, the two age groups did not differ in their appreciation of fairness, as assessed using subjective fairness ratings. CONCLUSIONS: These findings suggest that older adults are more rational in their behavior, accepting unfair offers even when they know they are unfair, as it is in their self-interest to accept small monetary values rather than nothing at all.

Different representations and strategies in mental rotation.

It is still debated whether holistic or piecemeal transformation is applied to carry out mental rotation (MR) as an aspect of visual imagery. It has been recently argued that various mental representations could be flexibly generated to perform MR tasks. To test the hypothesis that imagery ability and types of stimuli interact to affect the format of representation and the choice of strategy in performing MR task, participants, grouped as good or poor imagers, were assessed using four MR tasks, comprising two sets of 'Standard' cube figures and two sets of 'non-Standard' ones, designed by withdrawing cubes from the Standard ones. Both good and poor imagers performed similarly under the two Standard conditions. Under non-Standard conditions, good imagers performed much faster in non-Standard objects than Standard ones, whereas poor imagers performed much slower in non-Standard objects than Standard ones. These results suggested that (1) individuals did not differ in processing the integrated Standard object, whereas (2) in processing the non-Standard objects, various visual representations and strategies could be applied in MR by diverse individuals: Good imagers were more flexible in generating different visual representations, whereas poor imagers applied different strategies under different task demands.

Effects of age on inhibitory control are affected by task-specific features.

Older adults have been argued to have impoverished inhibitory control compared to younger adults. However, these effects of age may depend on processing speed and their manifestation may furthermore depend on the type of inhibitory control task that is used. We present two experiments that examine age effects on inhibition across three tasks: a Simon arrow, static flanker and motion flanker task. The results showed overall slower reaction times (RTs) for older adults on all three tasks. However, effects of age on inhibition costs were only found for the Simon task, but not for the two flanker tasks. The motion flanker task furthermore showed an effect of baseline processing speed on the relation between age and inhibition costs. Older adults with slower baseline responses showed smaller inhibition costs, suggesting they were affected less by the flanker items than faster older adults. These findings suggest that effects of age on inhibition are task dependent and can be modulated by task-specific features such as the type of interference, type of stimuli and processing speed.

Brain Information Sharing During Visual Short-Term Memory Binding Yields a Memory Biomarker for Familial Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) as a disconnection syndrome which disrupts both brain information sharing and memory binding functions. The extent to which these two phenotypic expressions share pathophysiological mechanisms remains unknown. OBJECTIVE: To unveil the electrophysiological correlates of integrative memory impairments in AD towards new memory biomarkers for its prodromal stages. METHODS: Patients with 100% risk of familial AD (FAD) and healthy controls underwent assessment with the Visual Short-Term Memory binding test (VSTMBT) while we recorded their EEG. We applied a novel brain connectivity method (Weighted Symbolic Mutual Information) to EEG data. RESULTS: Patients showed significant deficits during the VSTMBT. A reduction of brain connectivity was observed during resting as well as during correct VSTM binding, particularly over frontal and posterior regions. An increase of connectivity was found during VSTM binding performance over central regions. While decreased connectivity was found in cases in more advanced stages of FAD, increased brain connectivity appeared in cases in earlier stages. Such altered patterns of task-related connectivity were found in 89% of the assessed patients. CONCLUSIONS: VSTM binding in the prodromal stages of FAD are associated to altered patterns of brain connectivity thus confirming the link between integrative memory deficits and impaired brain information sharing in prodromal FAD. While significant loss of brain connectivity seems to be a feature of the advanced stages of FAD increased brain connectivity characterizes its earlier stages. These findings are discussed in the light of recent proposals about the earliest pathophysiological mechanisms of AD and their clinical expression.

Health professionals are unaware of anosognosia.

"Implicit awareness" may be inferred from compliance with medical treatment, even when the patient explicitly denies the need for treatment. Such compliance may cause medics and other health professionals to underestimate the frequency of anosognosia and its effects on the lives of patients and carers. We report survey data showing that health professionals do indeed consider anosognosia following stroke to be relatively uncommon and unimportant, in contrast with evidence on its true frequency and impact. Mograbi and Morris' emphasis on the distinction between implicit and explicit awareness may promote increased recognition of anosognosia amongst health professionals.

Amnesiacs might get the gist: reduced false recognition in amnesia may be the result of impaired item-specific memory.

It is a common finding in tests of false recognition that amnesic patients recognize fewer related lures than healthy controls, and this has led to assumptions that gist memory is damaged in these patients (Schacter, Verfaellie, & Anes, 1997, Neuropsychology, 11; Schacter, Verfaellie, Anes, & Racine, 1998, Journal of Cognitive Neuroscience, 10; Schacter, Verfaellie, & Pradere, 1996, Journal of Memory and Language, 35). However, clinical observations find that amnesic patients typically hold meaningful conversations and make relevant remarks, and there is some experimental evidence highlighting preserved immediate recall of prose (Baddeley & Wilson, 2002, Neuropsychologia, 40; Gooding, Isaac, & Mayes, 2005, Neuropsychologia, 43; Rosenbaum, Gilboa, Levine, Winocur, & Moscovitch, 2009, Neuropsychologia, 47), which suggests that amnesiacs can get the gist. The present experiment used false recognition paradigms to assess whether the reduced rate of false recognition found in amnesic patients may be a consequence of their impaired item-specific memory. It examined the effect of increasing the item-specific memory of amnesic patient DA by bringing her to criterion on relevant study-lists and compared her performance on a false recognition paradigm with a group of 32 healthy young adults. Results indicated that when DA's item-specific memory was increased she was more able to gist and her performance was no different to the healthy young adults. Previous assumptions that gist memory is necessarily damaged in amnesia might therefore be revisited, since the reduced rate of false recognition could be caused by impaired item-specific memory. The experiment also highlights a positive relationship between item-specific and gist memory which has not previously been accounted for in false-recognition experiments.

Dual task performance in Parkinson's disease.

Several studies have found dual tasking to be impaired in Alzheimer's disease (AD), but unaffected by healthy ageing. It is not known if this deficit is specific to AD, or also present in other neurodegenerative disorders that can occur in later life, such as Parkinson's disease (PD). Therefore, this study investigated dual tasking in 13 people with PD, 26 AD and 42 healthy age-matched controls. The people with AD demonstrated a specific impairment in dual tasking, which worsened with increasing disease severity. The people with PD did not demonstrate any deficits in dual tasking ability, when compared to healthy controls, suggesting that the dual task impairment is specific to AD.

Representational pseudoneglect in an auditory-driven spatial working memory task.

Two experiments explored lateralized biases in mental representations of matrix patterns formed from aural verbal descriptions. Healthy participants listened, either monaurally or binaurally, to verbal descriptions of 6 by 3 matrix patterns and were asked to form a mental representation of each pattern. In Experiment 1, participants were asked to judge which half of the matrix, left or right, contained more filled cells and to rate the certainty of their judgement. Participants tended to judge that the left side was fuller than the right and showed significantly greater certainty when judging patterns that were fuller on the left. This tendency was particularly strong for left-ear presentation. In Experiment 2, participants conducted the same task as that in Experiment 1 but were also asked to recall the pattern for the side judged as fuller. Participants were again more certain in judging patterns that were fuller on the left-particularly for left-ear presentation-but were no more accurate in remembering the details from the left. These results suggest that the left side of the mental representation was represented more saliently but it was not remembered more accurately. We refer to this lateralized bias as "representational pseudoneglect". Results are discussed in terms of theories of visuospatial working memory.

Specific deficit of colour-colour short-term memory binding in sporadic and familial Alzheimer's disease.

Short-term memory binding of visual features which are processed across different dimensions (shape-colour) is impaired in sporadic Alzheimer's disease, familial Alzheimer's disease, and in asymptomatic carriers of familial Alzheimer's disease. This study investigated whether Alzheimer's disease also impacts on within-dimension binding processes. The study specifically explored whether visual short-term memory binding of features of the same type (colour-colour) is sensitive to Alzheimer's disease. We used a neuropsychological battery and a short-term memory binding task to assess patients with sporadic Alzheimer's disease (Experiment 1), familial Alzheimer's disease (Experiment 2) due to the mutation E280A of the Presenilin-1 gene and asymptomatic carriers of the mutation. The binding task assessed change detection within arrays of unicoloured objects (Colour Only) or bicoloured objects the colours of which had to be remembered separately (Unbound Colours) or together (Bound Colours). Performance on the Bound Colours condition (1) explained the largest proportion of variance between patients (sporadic and familial Alzheimer's disease), (2) combined more sensitivity and specificity for the disease than other more traditional neuropsychological tasks, (3) identified asymptomatic carriers of the mutation even when traditional neuropsychological measures and other measures of short-term memory did not and, (4) contrary to shape-colour binding, correlated with measures of hippocampal functions. Colour-colour binding and shape-colour binding both appear to be sensitive to AD even though they seem to rely on different brain mechanisms.

Dual task impairments in vascular dementia.

Several studies have shown that people with Alzheimer's disease (AD) demonstrate difficulties in doing two things at once or 'dual-tasking' and that this dual task impairment is insensitive to normal ageing, chronic depression or prodromal conditions like Mild Cognitive Impairment. It is not known, however, if this impairment is specific to AD, or also present in other dementias, such as vascular dementia (VaD). In this study 15 people with VaD, 25 healthy age-matched and 25 healthy young controls were assessed using a paper and pencil dual tasking paradigm and several measures of working and episodic memory. Age had no effect on dual task performance, but the VaD patients demonstrated a significant impairment in dual tasking ability. Performance on the memory measures was instead affected by age with a further deterioration in the VaD patients. Both dual tasking and memory ability were significantly correlated with disease severity, as assessed by the MMSE. These results indicate that performance on the dual task could be a specific indicator of pathological ageing.

Spatial negative priming in bilingualism.

Balanced bilinguals have been shown to have an enhanced ability to inhibit distracting information. In this study, we investigated the hypothesis that the bilinguals' efficiency in inhibitory control can be advantageous in some conditions, but disadvantageous in others-for example, negative priming conditions, in which previously irrelevant information becomes relevant. Data collected in a target-stimulus locating task from 29 early bilingual adults and 29 age-matched monolinguals showed that the bilinguals' greater inhibition of irrelevant spatial information (i.e., the position of a distractor stimulus) resulted in a smaller effect of the distractor presence (i.e., a smaller difference in error rates in trials with and without distractors) and a larger negative priming effect (i.e., a larger difference between the error rates shown in trials wherein the target position corresponded to the position of the previous-trial distractor and trials wherein the target was presented in a previously vacant position). These findings support the hypothesis of specific nonlinguistic cognitive effects of bilingualism on inhibitory control functions, which are not necessarily reflected in cognitive advantages.

Selective impairment in visual short-term memory binding.

Dissociations within binding in perception have been reported after brain damage. In short-term memory (STM), feature binding and feature processing appear to rely on separate processes. However, dissociations within binding in STM following brain damage have not been reported to date. We report on the case E.S. who, after removal of a left medial sphenoid ridge meningioma, developed a selective impairment of visual STM (VSTM) binding. We found that, despite having normal perceptual binding, E.S. was unable to retain in VSTM features bound into objects while she could retain individual features as well as controls did (Experiments 1-2, 4, and 6). Her verbal STM for bound and single features remains intact (Experiments 3 and 5). E.S.'s performance suggests that STM binding can be dissociated from STM for single features across visual and verbal domains. The results are discussed in the light of current models of STM.

Age and binding within-dimension features in visual short-term memory.

Older adults have difficulties in binding information in long-term memory (e.g. objects with colours). The effect of age on visual short-term memory (VSTM) binding is less well understood. Recent evidence has suggested that older adults' VSTM for colours bound to shapes or for locations bound in configural representations may be preserved. In two experiments we investigated whether this lack of an age effect on VSTM for bound features can be reproduced when features are drawn from the same dimension (i.e. colour-colour binding) and when spatial clues are not available. Younger and older adults were presented with two sequential arrays of unicoloured or bicoloured objects and their accuracy in detecting changes between arrays was used as the measure of memory performance. Memory was assessed using a change detection paradigm for unicoloured objects and for bicoloured objects with changes in colour conjunctions (i.e. colours swapping between objects) or with changes in non-conjunctive colours (i.e. colours replacing colours in the study array). Both young and older adults were less accurate at remembering objects defined by colour conjunctions than unicoloured objects or objects composed of two non-conjunctive colours (Experiment 1). Increasing task demands in terms of memory and perceptual load had no greater effect on the older than the younger adults (Experiment 2). We suggest (1) that colours were not integrated into single units in VSTM; (2) that remembering the binding between colours has a cost; and (3) that neither of these effects are age-dependent.