Common marmosets (Callithrix jacchus) excel in a one-trial spatial memory test, yet perform poorly in a classical memory task

Four methods of assessing the validity of performance on a word recognition test were compared among 609 criminal defendants engaged in competency-to-stand-trial evaluations. One of the methods, the “normative” floor effect strategy, involves comparing an individual's performance to the average performance of individuals with true memory impairment. In this sample, 16.9% of defendants performed below the normative floor for individuals with true impairment. Another method, the “personal” floor effect strategy, identifies performance as suspect when individuals perform below a level for which they themselves have already demonstrated intact ability. In this sample, the personal floor effect strategy identified fewer instances of suspicious performance (15.6%), but the strategy may be less sensitive to true memory impairment than the normative floor effect. Consequently, the personal floor effect strategy may be more compelling as evidence of poor effort or bad intentions on memory testing. Convergent validity of the personal floor effect strategy is demonstrated over four analyses.

Cholinesterase inhibitors and memory

The validity of two malingering tests, the newly developed Amsterdam Short-Term Memory (ASTM) test and the Distraction test (Baker, Hanley, Jackson, Kimmance, & Slade, 1993) was examined in a group of patients with closed-head injury (CHI), a normal control group, and a control group with instruction to feign memory deficits. Both control groups consisted of first-degree relatives of the patients. The ASTM test is a forced-choice verbal memory test, based on the technique of symptom validity testing. Stimulus material was chosen from category norms, and chance level is not transparent. The CHI and normal control groups scored near ceiling on the ASTM test, whereas the feigned deficit group scored significantly worse. The ASTM test classified all subjects correctly. Contrary to expectation, the Distraction test appeared to be invalid. The score profiles of the CHI and feigning groups on conventional memory and concentration tests were indistinguishable from each other. Thus, the ASTM test may be very useful for the detection of malingering and other kinds of less than optimal performance. The test may readily be constructed in any language for which category norms are available.

Drugs and human memory (part 2). Clinical, theoretical, and methodologic issues.

Visual and verbal learning in a genetic metabolic disorder

Explicit and implicit memory in the elderly: Evidence for double dissociation involving medial temporal- and frontal-lobe functions.

Ketamine is intravenous anaesthetic with NMDA-glutamate receptors mechanism of action. Male Wistar rats were treated with saline (group A) or 10, 15 or 20 mg/kg of ketamine (groups B, C and D, respectively). For active avoidance test an automatic reflex conditioner was used. The observed variables were number of avoidances, escapes and intertrial crossings. Step-through and step-down passive avoidance tests were done with learning and memory retention test. Criteria for step-through test were latency of reactions of 180 sec in the light chamber. Criteria for step-down test were latency of reaction of 60 sec on the platform. The hot-plate test evaluates the reaction time of the rats dropped on a heated surface. The analgesy-meter test exerts a force increased at constant rate. In active avoidance test the controls increased the number of avoidances during learning and memory tests. Ketamine in all doses used increased the number of avoidances during learning and in memory test. Controls did not change the number of escapes, but the ketamine treated animals decreased it. The number of intertrial crossings was not changed by controls or ketamine-treated rats during learning and memory tests. In passive avoidance tests the controls and ketamine-treated rats increased the latency time during learning and memory retention tests. In hot-plate analgesic test and in analgesy-meter test the controls and ketamine-treated rats did not change the latency of reaction. The results suggest that ketamine improves learning and memory processes and has no analgesic effect in the doses applied.

ABSTRACTSex differences in cognition are often predicted based on ecological roles, particularly when one sex engages more extensively in specific behaviors that might be subject to selective pressure. In zebra finches (Taeniopygia guttata), males choose and deposit the majority of the material into the nest and might therefore exhibit enhanced physical cognition. We tested this hypothesis using the trap‐gap task, a modified shape–frame matching paradigm designed to evaluate how animals assess object–hole relationships. In this task birds pulled food‐containing trays attached to strings through gaps in barriers. Birds were trained on either a barrier task (choosing the correct gap size to fit a tray between barriers with different gaps) or a tray task (choosing the correct tray size between barriers with the same gap), then transferred to the alternate task (called the transfer test). Contrary to predictions, males and females showed no differences in the number of trials to reach learning criteria or in the number of errors in the transfer test. Birds required more trials, on average, to learn the barrier task compared to the tray task, and the transfer test was at chance, suggesting birds relied on absolute cue‐based strategies rather than learning the object–gap relationship (relative cue‐based strategies). These findings align with previous research showing no sex differences in learning about material properties in zebra finches, despite males' dominant role in nest building. The lack of sex differences in performance may stem from a mismatch in spatial frames of reference: while nest building relies on an egocentric (body‐centered) frame, the trap‐gap tasks uses an allocentric (object‐centered) frame. Our findings highlight the complexity of linking behavioral sex roles to cognitive specialization and underscore the importance of task design and ecological relevance in comparative cognition research.

To characterize the linguistic profile of adults and elderly with Down Syndrome (DS) using the Arizona Battery for Communication Disorders of Dementia (ABCD). Thirty adult individuals with DS were evaluated through the MoCA cognitive battery, four functional scales (Pfeffer, Lawton-IADL, Katz-IADL and IQCODE) and the ABCD battery, which evaluates Mental State, Episodic Memory, Linguistic Expression, Linguistic Comprehension and Visuospatial Construction. The scores obtained by the individuals in the ABCD were correlated to those obtained on the Lawton-IADL scale. Individuals with DS had significantly lower performance than cognitively normal adults and elderly as described in Brazilian studies. Due to the lack of similar studies in our country, we compared our results to those of elderly with Alzheimer's Disease (AD), verifying that the performance of the DS population is similar to that of AD patients, although the former presented better scores on episodic immediate memory tests. There was a significant positive correlation between the scores obtained in the Lawton-IADL and those on the constructs Mental State, Episodic Memory, Linguistic Comprehension and Total ABCD. The ABCD battery is a useful tool in the evaluation of adults and elderly with DS and the performance of individuals in this battery correlates with indices of functionality. This is a pioneer study in Brazil, and it points to the need for a better characterization of the linguistic abilities of individuals with DS, in order to allow the elaboration of strategies that stimulate their communicative abilities as to promote greater social insertion for this population.

Cognitive evaluation in developing countries is a difficult undertaking due to low levels of schooling and particularly the illiteracy still frequent in the elderly. This study was part of the epidemiologic evaluation of dementia in Catanduva, Brazil, and had the objective of comparing the performance of illiterate and literate nondemented elderly individuals in 2 tests of long-term memory-the delayed recall of a word list from the CERAD and the delayed recall of common objects presented as simple drawings from the Brief Cognitive Screening Battery (BCSB). Fifty-one elderly subjects (23 illiterates) were evaluated, and the performance of the illiterates and literates differed in the CERAD memory test, but not in the BCSB memory test. This test may be more suitable for the assessment of long-term memory in populations with a high frequency of illiterates, and therefore might prove to be a useful screening tool for the diagnosis of dementia.

ABSTRACTCowan, Donnell, and Saults [(2013). A list-length constraint on incidental item-to-item associations. Psychonomic Bulletin & Review, 20, 1253–1258] examined incidental memory of whether two words had occurred in the same list or different lists, after the lists had been presented with an orienting task that did not require memorisation. Performance was superior for 3-word lists compared to 6- or 9-word lists, with memory for the longer lists near chance levels. Here we re-examine this phenomenon with methodological modifications to ensure that learning was incidental: we removed potential clues that a memory test would follow, eliminated trials with special mnemonic cues related to the orienting task, eliminated participants who suspected a memory test according to a post-experimental questionnaire, used signal detection measures to distinguish between memory sensitivity and bias, and tested list length with the relative serial position controlled. Incidental memory formed primarily for the most recent part of each list, an effect that was stronger than that of list length. The new evidence helps to constrain theories about the relation between working memory and incidental learning. A capacity-limited approach to the incidental-learning process still is possible but must be modified compared to Cowan et al., and the evidence is favourable to other theoretical approaches as well.

Longitudinal changes in odor identification performance and neuropsychological measures in aging individuals.

Tanimbar corellas, an important model in comparative cognition research, are endemic to the Tanimbar Islands, Indonesia, but were also introduced to several other locations with a tropical climate. Introduced psittacines offer valuable opportunities to test hypotheses at large temporal and spatial scales, such as geographic distribution of behaviours. Here, we report two opportunistic observations of Tanimbar corellas combining small wooden fragments with two types of tropical fruit (Ketapang and Pong-pong) in Singapore. The observations were recorded and uploaded to YouTube by a local bird-watcher. We analyse the behavioural similarities and differences between object combinations with the Pong-pong fruit in Singapore and extractive tool use on the Wawai fruit in Indonesia. Repeated insertions of the wooden fragment into the fruit and visible ingestion suggest that the combinatory behaviours were most likely related to foraging. This report provides first insights into the presence of advanced technical abilities in geographically separated Tanimbar corellas.

Trimethyltin (TMT) produces behavioral and cognitive deficits resulting, in part, from limbic system toxicity. To determine whether these effects result from learning deficits or accelerated memory loss, the present experiment examined two delay conditioning paradigms in rats previously treated with either saline or TMT. Saline-treated Long-Evans rats receiving injections of lithium after consuming saccharin-flavored water later avoided saccharin ingestion: the degree of avoidance varied inversely with the time (0.5, 3 or 6 h) separating initial saccharin availability and lithium injection. Rats treated with TMT (8 mg/kg IV, 30 days prior) showed impaired conditioning at the long but not the short or intermediate delay conditions, suggesting that the deficits were mnemonic and not associative. Similar delay-dependent deficits in rats treated with TMT were observed in a passive avoidance task that arranged one of two delays between response emission and shock delivery during training. The effects of TMT on delay conditioning were accompanied by reduced bodyweight and hippocampal pathology. In summary, TMT appears to alter the temporally dependent association of events (entering darkened compartment versus saccharin consumption) and consequences (foot shock versus lithium administration) during acquisition. Furthermore, the observed deficits in delay conditioning produced by TMT did not appear to be task specific, with similar effects determined with tests of both somatosensory and gustatory avoidance learning designed to distinguish between functional alterations due to deficits in memorial processes from those due to altered sensory, motor, or associative processes.

Sniffing out a link with Alzheimer's