Item versus associative information: Further comparisons of forgetting rates.

Four experiments are reported that extend previous research and firmly demonstrate that item information is more susceptible to decay or interference than is associative information. The forgetting rate for single words is shown to be greater than the forgetting rate for associations between random pairs of words in a continuous recognition paradigm using both yes–no (Exp 1) and forced-choice (Exps 2 and 3) test procedures. Item recognition is also shown to decline more than associative discrimination between an immediate and an end-of-session delayed test in the study–test paradigm. The findings provide further empirical support for a process-oriented distinction between item and associative information and pose a challenge for global matching models of recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for spatial layouts in relation to age and schema typicality.

The hypothesis that prior experience, specifically a knowledge-based schema for typical house layouts, can compensate for age declines in spatial memory was evaluated in 4 experiments. Old and young adults explored and subsequently recalled house layouts presented 1 room at a time on a computer screen. The findings failed to support the compensation hypothesis in that schema-relevant layouts facilitated recall equivalently for the 2 age groups. Violation of a typical house schema had a more negative effect on recall of the older group. Individual differences in spatial visualization ability explained much of the age difference in performance but not the effects of schema manipulations. It was concluded that there is age invariance in the facilitatory effects of relevant prior knowledge on spatial memory but an age-related decrease in the ability to inhibit irrelevant prior knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal versus spatial information processing theories of hippocampal function.

Several articles by A. H. Black, L. Nadel, J. O'Keefe, and their co-workers (1974, 1975, 1976, 1979) propose that the primary function of the hippocampus is to process spatial information. Although the spatial information processing view of hippocampal function accounts for much of the available data, it cannot account for the data from the classically conditioned rabbit nictitating membrane response preparation. The present article reviews these data and suggests that the hippocampus is involved in the processing of temporal as well as spatial information. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the course of forgetting in very long-term memory.

For practical reasons, little information is available about memory across very long learning-retention intervals. To determine the time course of forgetting in very long-term memory, a memory test was constructed that sampled events (former one-season television programs) that had occurred during a single year from 1 to 15 years ago. Updated versions of the test were administered each year for 9 consecutive years, and a forgetting curve was then calculated by superimposing the results from the nine tests. The best fitting function to the curve was monotonic and nonlinear. The findings show that forgetting in very long-term memory can be gradual and continuous for many years after learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Posttrial hippocampal stimulation and CER acquisition in the rat.

Gave 27 female Holtzman albino rats CER training, with each CS-UCS pairing followed by hippocampal stimulation through chronically implanted electrodes. Findings show that (a) localized posttrial stimulation may have blocked CER acquisition, although individual Ss differed considerably in degree of impairment; (b) the blocking was due neither to an implant-produced lesion nor to reinforcing properties of the stimulation; and (c) stimulation passed through separated electrodes spanning a large area of hippocampus was effective at both high and low current levels, with or without concomitant electrographic afterdischarges. Results indicate that posttrial hippocampal stimulation interferes with CER consolidation, and suggest that there may be critical locations within hippocampus whose activity must be disrupted in order for the blocking to occur. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conversational conventions, order of information acquisition, and the effect of base rates and individuating information on social judgments.

Numerous studies have shown that people underuse base-rate information in making social judgments and rely instead almost exclusively on individuating information. Seven studies reported here demonstrate that this occurred partly because most past studies gave Ss base-rate information before giving them individuating information. A recency effect in the use of base-rate and individuating information is demonstrated using a set of reasoning problems of varying character. The recency effect is shown to be the result of Ss' inferences (based on conversational conventions) that the experimenter believes that Ss should rely most on the piece of information presented last. Additional evidence discredits the hypothesis that the recency effect is due to heightened availability of more recently acquired information in memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An evaluation of spatial information processing in aged rats.

The spatial learning abilities of young, middle-age, and senescent rats were investigated in 2 experiments using several versions of the Morris water maze task. In Exp I, Long-Evans hooded rats were trained to find a submerged escape platform hidden within the water maze. Aged Ss exhibited acquisition deficits compared with either young or middle-age Ss. With continued training, all age groups eventually achieved comparable asymptotic levels of performance. To identify the basis of the age-related impairments observed in Exp I, naive young and aged Ss in Exp II were initially tested for their ability to locate a cued escape platform in the water maze. The escape latencies of both young and aged Ss rapidly decreased to equivalent asymptotic levels. Following cue training, young Ss exhibit a significant spatial bias for the region of the testing apparatus where the platform was positioned during training. In contrast, aged Ss showed no spatial bias. Training was continued in Exp II using a novel submerged platform location for each S. During these place training trials, the escape latencies of senescent Ss were longer than those of young Ss. These impairments were also accompanied by a lack of spatial bias among aged Ss relative to young controls. Results indicate that age-related impairments in water maze performance reflect a specific deficit in the ability of aged rats to utilize spatial information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of spatial location in remembering and forgetting peripheral words.

This study examined whether spatial location mediates intentional forgetting of peripherally presented words. Using an item-method directed forgetting paradigm, words were presented in peripheral locations at study. A recognition test presented all words at either the same or a different location relative to study. Results showed that while recognition of Remember words was unaffected by test location, when Forget words were presented in the same location at test as at study, recognition accuracy was significantly greater than when presented in a different location. Experiment 2 showed that the speed to localize a previously studied word was faster when it was presented in the same rather than a different study-test location but that the magnitude of this spatial priming was unaffected by memory instruction. We suggest that the location of peripherally presented words is represented in memory and can aid the retrieval of poorly encoded words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in retrieval: Trace-dependent and cue-dependent forgetting.

A multitrial free recall task was presented to 3 age groups of men and women (18-34, 50-64, and 65-83 yrs) under cued and noncued recall conditions to determine whether age-related differences in retrieval were attributable to the availability of elementary units (trace-dependent forgetting), the accessibility of higher order units (cue-dependent forgetting), or both. Results show significant age differences in words recalled, categories recalled (accessibility), and words recalled per category (availability). It is concluded that adult age differences in retrieval are a function of both cue-dependent and trace-dependent forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding and retrieval operations in relation to age.

In 2 experiments, the memory performance of a total of 40 young (mean age 18 yrs) and 40 elderly (mean age 75 yrs) Ss was compared in a procedure that allowed testing of the target words twice, first for recognition and then for cued recall. Conventional analyses of the recall and recognition data gave results that echoed previous findings that (a) significant age differences were found in recall but not in recognition, and (b) the recall differences were minimized when the target items were recalled in the context of cues highly related to the target items. In accordance with contemporary theoretical conceptions of memory, a feasible interpretation of these results is that memory loss is due to a retrieval deficit. However, further analyses showed that both young and older Ss failed to recognize many words that they subsequently recalled, suggesting that some caution is necessary in interpreting overall recall and recognition memory performance. Possible differences in encoding and retrieval processes as a function of age are discussed. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rate of acquisition, adult age, and basic cognitive abilities predict forgetting: New views on a classic problem.

Rate of forgetting is putatively invariant across individuals, sharing few associations with individual-differences variables known to influence encoding and retrieval. This classic topic in learning and memory was revisited using a novel statistical application, multilevel modeling, to examine whether (a) slopes of forgetting varied across individuals and (b) observed individual differences in forgetting shared systematic relations with adult age, learning speed, and cognitive ability. Participants (N = 136) received mnemonic training prior to memorizing 4-digit numbers to perfection, and retention was tested immediately after training and after 30 min, 24 hr, 7 weeks, and 8 months. Slower rate of learning to criterion, older age, and poorer cognitive performance predicted accelerated forgetting with associations most pronounced within 24 hr from baseline. Observed correlates of differential forgetting slopes are similar to those previously found to affect encoding, suggesting continuity rather than asymmetry of prediction for these memory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cardiorespiratory fitness, hippocampal volume, and frequency of forgetting in older adults.

Objective: The purpose of this study was to extend our earlier work to determine the extent to which cardiorespiratory fitness is associated with the frequency of memory problems via its effects on the hippocampus and spatial working memory. We hypothesized that age, sex, education, body composition, and physical activity were direct determinants of fitness, which, in turn, influenced frequency of forgetting indirectly through hippocampal volume and spatial working memory. Method: We conducted assessments of demographic characteristics, Body Mass Index (BMI), physical activity, cardiorespiratory fitness, hippocampal volume, spatial working memory, and frequency of forgetting in 158 older adults (M age = 66.49). Path analyses within a covariance modeling framework were used to examine relationships among these constructs. Results: Sex, age, BMI, and education were all significant determinants of cardiorespiratory fitness. The hypothesized path models for testing the effects of fitness on frequency of forgetting through hippocampal volume and accuracy and speed of spatial working memory all fit the data well. Conclusions: Our findings suggest that older adults with higher levels of fitness show greater preservation of hippocampal volume, which, in turn, is associated with more accurate and faster spatial memory and fewer episodes of forgetting. Given the proportion of older adults reporting memory problems, it is necessary to determine whether improvements in fitness brought about by physical activity interventions can result in subsequent attenuation of memory problems or potentially in improvements in memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A comparison of forgetting in an implicit and explicit memory task.

Among possible criteria for distinguishing separate memory systems for implicit and explicit memory is that of substantial differences in either the form or rate of forgetting. Prior literature has claimed both differential forgetting and equivalent forgetting for implicit and explicit tasks. Existing experimental data for word-stem completion and explicit control tasks were reviewed and shown to be inconclusive. Our experiments measure forgetting in comparable implicit and explicit memory tasks of stem completion and stem cued recall. The form and the rate of forgetting are essentially the same for these implicit and explicit tasks. Levels of processing and task conditions differ only in the level of initial learning or availability. Thus, either the implicit and explicit task reflect traces in the same memory system or they reflect traces in different systems that have identical forgetting dynamics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Knowledge-based information acquisition: Norms and the functions of consensus information.

Mill's (1872/1973) method of difference prescribes that the lay scientist should use consensus information as a control condition for the person and distinctiveness information as a control condition for the stimulus when analyzing their causal effects on the occurrence of the target event. However, in studies of information acquisition, subjects have shown a consistent preference for distinctiveness information when answering causal questions about the person, and for consensus information when answering causal questions about the stimulus. To explain this discrepancy, we distinguish between the evaluative, contrastive, and corroborative functions of consensus and distinctiveness information. In addition, we suggest that Ss seek consensus information only if it is relevant to the question posed to them, and if they cannot supply it from their own presupposed knowledge of behavioral norms. We report 4 information acquisition experiments that provide support for our analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Systematic comparison of the effects of hippocampal and fornix-fimbria lesions on acquisition of three configural discriminations

The effects of lesions to the hippocampal system on acquisition of three different configural tasks by rats were tested. Lesions of either the hippocampus (kainic acid/colchicine) or fornix-fimbria (radiofrequency current) were made before training. After recovery from surgery, rats were trained to discriminate between simple and compound-configural cues that signaled the availability or nonavailability of food when a bar was pressed. When positive cues were present, one food pellet could be earned by pressing a lever after a variable time had elapsed. The trial terminated on food delivery (variable interval 15 s). This procedure eliminates some possible alternative explanations of the results of previous experiments on configural learning. Hippocampal lesions increased rates of responding and retarded acquisition of a negative patterning task (A+, B+, AB-); using a ratio measure of discrimination performance these lesions had a milder retarding effect on a biconditional discrimination (AX+, AY-, BY+, BX-), and they had no effect on a conditional context discrimination (X: A+, B-; Y: A-, B+). Fornix-fimbria lesions did not affect acquisition of any of these tasks but increased rates of responding. The results suggest that several task parameters determine the involvement of the hippocampus in configural learning; however, all tasks tested can also be learned to some extent in the absence of an intact hippocampal system, presumably by other learning/memory systems that remain intact following surgery. The lack of effect of fornix-fimbria lesions on any of these tasks suggests that retrohippocampal connections with other brain areas may mediate hippocampal contributions to the learning of some configural tasks. An analysis of these results and of experiments on spatial learning situations suggests that involvement of the hippocampus is a function of the degree to which correct performance depends on a knowledge of relationships among cues in a situation.     

Short- and long-term memory retrieval: A comparison of the effects of information load and relatedness.

The separate applications of the Sternberg and fact-retrieval paradigms promote a view that short- and long-term memory are functionally distinct. However, effects of information load and relatedness, observed in both paradigms, support a more unified approach to memory retrieval. The two experiments of this article allow for direct comparison of these effects as observed in a fact-retrieval task, a Sternberg task, and a hybrid precuing task. These experiments are motivated by an associative approach in which performance in all tasks is seen to depend upon a parallel search driven by spreading activation. Decision-time data are explained in an indirect-pathway model with two important features: (a) Pretrial activation levels of areas in memory can vary to reflect differences between short-term and long-term retrieval; and (b) for related material, decisions can be based upon indirect pathways that connect the elements of a test probe through preexperimental associations in memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Countercontrol treatment of sleep-maintenance insomnia in relation to age.

Administered countercontrol behavioral therapy for sleep-maintenance insomnia to 34 insomniacs (aged 35–78 yrs) in small groups. 22 Ss received immediate and 12 received delayed treatment. Three self-report measures of sleep disruption were collected on daily sleep diaries at baseline, termination of treatment, 1-mo follow-up, and 12-mo follow-up. Although amount of time awake at night was correlated with age, response to treatment was not. Even though older Ss experienced more time awake after sleep onset prior to treatment, they were able to profit from therapy as well as the younger insomniacs. Countercontrol therapy reduced the sleep complaint for the total group by about 30% at the end of treatment, with gradual improvement continuing through a 4-wk follow-up. It is suggested, however, that sleep-maintenance insomnia may be more difficult to treat than sleep-onset problems. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential forgetting of superordinate and subordinate information acquired from prose material.

Investigated the construct validity of a recognition test based on the structure of a prose passage and attempted to relate both present and past data on memory for prose to current approaches to human memory. 44 undergraduates read a 1,600-word prose passage after which half of them took a recognition test dealing with the content of the passage, while the other half performed an unrelated task. Following a 2-day delay, both groups took the recognition test. Results indicate that there were different rates of forgetting for superordinate and subordinate ideas in the passage. Further analysis addressed the adequacy of D. P. Ausubel's (1963) subsumption theory and F. I. Craik and R. S. Lockhart's (see record 1973-20189-001) levels-of-processing framework for explaining the data on memory for prose. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic in vivo morphine administration facilitates primed-bursts-induced long-term potentiation of Schaffer collateral-CA1 synapses in hippocampal slices in vitro

In this study, the effects of chronic morphine administration (20-30 days) on long-term potentiation (LTP) were investigated at the Schaffer collateral-CA1 pyramidal cell synapses of the rat hippocampal slices. Orthodromic population spike (OPS) amplitude and delay (peak latency) were measured as indices of increase in synaptic efficacy. The amounts of LTP of OPS delay and LTP of OPS amplitude were higher in slices from dependent rats. Perfusion of slices from control and dependent rats with morphine containing ACSF and delivering tetanic stimulation, showed that short-term presence of morphine could not mimic the LTP enhancing effects of chronic morphine administration, however, attenuated the amount of LTP of OPS amplitude in slices of dependent rats. This study supports the hypothesis that the susceptibility of CA1 synapses to plastic changes increases by chronic, not acute exposure to morphine and suggests that a withdrawal phenomenon might be an underlying mechanism for the observed augmented LTP of OPS amplitude in slices of dependent rats.