Associative and serial-order information: Different modes of operation?

Two versions of a distributed-memory model, one for associative information and one for serial-order information, leave open the question of whether there are two different modes of operation or only one. An analysis of these two versions showed that differential predictions emerge when one considers the role of item information. To test these predictions, a standard item-recognition task (Sternberg, 1966) was embedded in a paired-associate probe-recognition task, a serial-order probe-recognition task, or both. The item-recognition serial-position curves were quite different in the paired-associate and the serial-order conditions, and followed the paired-associate condition when the two were combined. In general, the results were consistent with the predictions of the distributed-memory models, and supported the idea of different modes of operation rather than a single common mode of operation.     

A quantitative theory of the concept identification processes in the Hull paradigm

A model of concept identification and paired-associate learning processes as they occur in a concept acquisition paradigm developed by Hull was derived from a cue selection theory of learning. The model predicts that paired-associate learning occurs in an all-or-none manner and that concept identification leads to all-or-none transfer. Both predictions were confirmed.     

Effects of aging on the magnitude and accuracy of quality-of-encoding judgments

Age invariance in monitoring associative learning has been the norm in numerous investigations concerning how accurately people predict future recall, predictions that are based partly on people's beliefs about forgetting. In this study, we obtained a measure of monitoring that is minimally influenced by beliefs about forgetting. Participants made quality-of-encoding (QUE) judgments by rating how well each item had been encoded. In 2 experiments, older and younger adults studied 60 paired-associate items; immediately after studying each one, they made a QUE judgment. Each item was presented at a 4-s or 8-s presentation rate. QUEs from both age groups were sensitive to the production of different strategies, presentation rate, and item characteristics. Reliable age differences in the correlation of QUEs and subsequent recall were found for related items but not for unrelated items. The outcomes indicate similar processes for generating QUE judgments by older and younger adults, but they also suggest the possibility of an age-related deficit in the accuracy of monitoring encoding in some experimental conditions.     

Comparisons of learning procedures: Effects of constant and random presentations

The retention interval hypothesis (Izawa 1972) was formulated on the basis of retention interval distributions given in random order to account for inconsistent performance differences between anticipation and study-test procedures, which have been regarded as a puzzle for nearly two decades. Under the anticipation procedure a presentation of the stimulus term of a paired-associate (a test event) is immediately followed by a presentation of both stimulus and response terms of the pair (a study event), whereas under the study-test procedure, study and test events are given on separate cycles. The retention interval hypothesis was specifically tested in a situation without any random distributions of the retention intervals i.e., under a constant item presentation order from cycle to cycle, in addition to random presentation orders, in a paired-associate learning experiment, using 80 college students. As predicted by the theory, significantly superior performances were obtained for the study-test method vis-à-vis the anticipation method also under a constant item presentation order. The constant presentation-order- arrangements significantly outperformed the random ones. Directions for further theoretical elaborations are suggested.     

Source memory in the absence of successful cued recall

Five experiments were conducted to address the question of whether source information could be accessed in the absence of being able to recall an item. The authors used a paired-associate learning paradigm in which cue-target word pairs were studied, and target recall was requested in the presence of the cue. When target recall failed, participants were asked to make a source judgment of whether a man or woman spoke the unrecalled item. In 3 of the 5 experiments, source accuracy was at or very close to chance. By contrast, if cue-target pairs were studied multiple times or participants knew in advance of learning that a predictive judgment would be required, then predictive source accuracy was well above chance. These data are suggestive that context information may not play a very large role in metacognitive judgments such as feeling-of-knowing ratings or putting one into a tip-of-the-tongue state without strong and specific encoding procedures. These same results also highlight the important role that item memory plays in retrieving information about the context in which an item was experienced.     

Application of Bower's one-element model to paired-associate learning by pigeons

Bower's (1961) all-or-none model of human paired-associate learning was applied to individual data supplied by three pigeons. When the center one of three keys was illuminated with red light or with three white dots in a vertical array on a black ground, pecking on the left key was reinforced. When the center key was lighted green or with a horizontal array of three white dots on a black ground, pecking on the right key was reinforced. The left and right keys were illuminated with white light. The task was considered to be analogous to learning a paired-associate list of four pairs involving four stimulus items and two response items. The model was evaluated by comparing the following model predictions with values obtained from each animal: trials-to-criterion, standard deviation of trials-to-criterion, standard deviation of errors-to-criterion, mean error runs, mean error runs of lengths one to four, and autocorrelations of errors of lags one to three. Most of the predictions based upon the model were in close agreement with the obtained data.     

Mental representations of spatial and nonspatial relations

Four experiments investigated the representation and integration in memory of spatial and nonspatial relations. Subjects learned two-dimensional spatial arrays in which critical pairs of object names were semantically related (Experiment 1), semantically and episodically related (Experiment 2), or just episodically related (Experiments 3a and 3b). Episodic relatedness was established in a paired-associate learning task that preceded array learning. After learning an array, subjects participated in two tasks: item recognition, in which the measure of interest was priming; and distance estimation. Priming in item recognition was sensitive to the Euclidean distance between object names and, for neighbouring locations, to nonspatial relations. Errors in distance estimations varied as a function of distance but were unaffected by nonspatial relations. These and other results indicated that nonspatial relations influenced the probability of encoding spatial relations between locations but did not lead to distorted spatial memories.     

Encoding fluency is a cue used for judgments about learning

The authors used paired-associate learning to investigate the hypothesis that the speed of generating an interactive image (encoding fluency) influenced 2 metacognitive judgments: judgments of learning (JOLs) and quality of encoding ratings (QUEs). Results from Experiments 1 and 2 indicated that latency of a keypress indicating successful image formation was negatively related to both JOLs and QUEs even though latency was unrelated to recall. Experiment 3 demonstrated that when concrete and abstract items were mixed in a single list, latency was related to concreteness, judgments, and recall. However, item concreteness and fluency influenced judgments independently of one another. These outcomes suggest an important role of encoding fluency in the formation of metacognitive judgments about learning and future recall.     

MINERVA 2: A simulation model of human memory

An overview of a simulation model of human memory is presented. The model assumes: (1) that only episodic traces are stored in memory, (2) that repetition produces multiple traces of an item, (3) that a retrieval cue contacts all memory traces simultaneously, (4) that each trace is activated according to its similarity to the retrieval cue, and (5) that all traces respond in parallel, the retrieved information reflecting their summed output. The model has been applied with success to a variety of phenomena found with human subjects in frequency and recognition judgment tasks, the schema-abstraction task, and paired-associate learning. Application of the model to these tasks is briefly summarized.     

Learning pictures and words: The role of implicit verbal labeling

In two experiments (Ns = 144 and 192), second, fourth, and sixth graders learned pairs of pictures or of words, and were tested for both item learning (either with pictures or words) and associative learning. By analysis of false recognition errors, it was determined that implicit verbal labeling occurred only among the older two groups. However, there was no evidence that this labeling affected paired-associate learning.     

Lexical learning in bilingual adults: the relative importance of short-term memory for serial order and phonological knowledge

Studies of monolingual speakers have shown a strong association between lexical learning and short-term memory (STM) capacity, especially STM for serial order information. At the same time, studies of bilingual speakers suggest that phonological knowledge is the main factor that drives lexical learning. This study tested these two hypotheses simultaneously in participants with variable levels of English-French bilingual proficiency. A word-nonword paired-associate learning task was administered, with nonwords obeying French phonotactic patterns. French phonological knowledge was estimated by a composite French proficiency score summarizing productive and receptive French vocabulary knowledge as well as quantitative and qualitative measures of French exposure. STM measures maximized retention of order information (serial order reconstruction) or retention of phonological item information (single nonword delayed repetition). The French proficiency score and the serial order STM measure independently predicted performance on the paired-associate learning task. These results highlight the conjoined role of phonological knowledge and serial order STM in lexical learning. Importantly, serial order STM remains a strong predictor of lexical learning, even for bilingual individuals who have broad phonological knowledge.     

Item and associative recognition with precuing and postcuing

M. Duncan & B. B. Murdock (2000) compared precued and postcued item recognition and serial recall showing precued-postcued differences for item recognition but not for serial recall. Precuing and postcuing refer to 2 conditions in which the instructions as to the type of recall test following the presentation of short lists of items is given before or after the list presentation. This methodology was extended here to a paired-associate task. In 2 experiments, short lists of paired associates were presented followed by single-item, old-new, or intact-rearranged pair recognition tests; test type was precued or postcued. A fast or slow presentation rate was used to discourage or encourage mediators. TODAM2 (a theory of distributed associative memory) predicts that there should be little or no cuing differences regardless of whether subjects use mediators to remember the pairs. As predicted the recognition data were essentially identical for the precued and postcued conditions.     

The roles of the medial prefrontal cortex and hippocampus in a spatial paired-association task

Although the roles of both the hippocampus and the medial prefrontal cortex (mPFC) have been suggested in a spatial paired-associate memory task, both areas were investigated separately in prior studies. The current study investigated the relative contributions of the hippocampus and mPFC to spatial paired-associate learning within a single behavioral paradigm. In a novel behavioral task, a pair of different objects appeared repeatedly across trials, but in different arms in a radial maze, and different rules were associated with those arms for reward. Specifically, in an "object-in-place" arm, the rat was required to choose a particular object associated with the arm. In a "location-in-place" arm, the animal was required to choose a certain within-arm location (ignoring the object occupying the location). Compared to normal animals, rats with ibotenic acid-based lesions in the hippocampus showed an irrecoverable impairment in performance in both object-in-place and location-in-place arms. When the mPFC was inactivated by muscimol (GABA(A) receptor agonist) in the normal animals with intact hippocampi, they showed the same severe impairment as seen in the hippocampal lesioned rats only in object-in-place arms. The results confirm that the hippocampus is necessary for a biconditional paired-associate task when space is a critical component. The mPFC, however, is more selectively involved in the object-place paired-associate task than in the location-place paired-associate task. The current task powerfully demonstrates an experimental situation in which both the hippocampus and mPFC are required and may serve as a useful paradigm for investigating the neural mechanisms of object-place association.     

The production effect in paired-associate learning: Benefits for item and associative information

In five experiments, we extended the production effect—better memory for items said aloud than for items read silently—to paired-associate learning, the goal being to explore whether production enhances associative information in addition to enhancing item information. In Experiments 1 and 2, we used a semantic-relatedness task in addition to the production manipulation and found no evidence of a production effect, whether the measure was cued recall or item recognition. Experiment 3 showed that the semantic-relatedness task had overshadowed the production effect; the effect was present when the semantic-relatedness task was removed, again whether cued recall or item recognition was the measure. Experiments 4 and 5 provided further evidence that production can enhance recall for word pairs and, using an associate recognition test with intact versus rearranged pairs, indicated that production may also enhance associative information. That production boosts memory for both types of information is considered in terms of distinctive encoding.     

Sources of information in metamemory: Judgments of learning and feelings of knowing

Metamnemonic judgments probe people’s awareness of their own memory processes. The research reviewed here is an examination of the sources of information that subjects use to make judgments of learning (e.g., paired-associate judgments, ease-of-recognition predictions, free-recall judgments), and feelings of knowing (e.g., speeded strategy decisions, tip-of-the-tongue states, feeling-of-knowing judgments). The general pattern in the data suggests that subjects use different sources of information to form these judgments. Target-based sources appear to be important in judgments made at the time of acquisition, whereas cue-based judgments appear to be important in judgments made at the time of retrieval. In general, these sources of information serve as useful heuristics, and metamnemonic judgments tend to be accurate.     

Fill-in and infill errors in order memory

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill-in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N-1. The error of interest is which item is recalled after this initial mistake. A fill-in error is the tendency to recall item N-1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill-in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill-in and infill errors.     

The PHQ-9 assesses depression similarly in men and women from the general population

Gender-based differential item functioning occurs when men and women respond differently to an item despite being similar on the trait assessed by that item. The Patient Health Questionnaire-9 (PHQ-9) is a prominent screening tool for depression. Researchers exploring whether the PHQ-9 exhibits gender-based differential item functioning have used only specialized samples (e.g., individuals with cancer or vision loss). We explored gender bias in the PHQ-9 by means of differential item functioning analyses in a population-based sample.We made use of the National Health and Nutrition Examination Surveys (NHANES, 2008), a population-based sample of the USA including 5995 participants. Differential item functioning was assessed using the Mantel-Haenszel chi-square test and by comparing item characteristic curves between men and women.All items exhibited negligible differential item functioning as demonstrated by the Mantel-Haenszel test, with absolute standardized mean differences ranging from 0.00 to 0.06. Item characteristic curves were similar between genders for all but one item. Item 5 (i.e., changes in appetite) exhibited very minor non-uniform differential item functioning, wherein extremely depressed women endorsed higher response options on this item compared to equally depressed men.Researchers can use the PHQ-9 without concern of gender biases, particularly in epidemiological research.     

Improving metacognitive accuracy: How failing to retrieve practice items reduces overconfidence

People often exhibit inaccurate metacognitive monitoring. For example, overconfidence occurs when people judge that they will remember more information on a future test then they actually do. The present experiments examined whether a small number of retrieval practice opportunities would improve participants’ metacognitive accuracy by reducing overconfidence. Participants studied Lithuanian–English paired associates and predicted their performance on an upcoming memory test. Then they attempted to retrieve one or more practice items (or none in the control condition) and made a second prediction. Experiment 1 showed that failing to retrieve a single practice item lead to improved subsequent performance predictions – participants became less overconfident. Experiment 2 directly manipulated retrieval failure and showed that again failure to retrieve a single practice item significantly improved subsequent predictions, relative to when participants successfully retrieved the practice item. Finally, Experiment 3 showed that additional retrieval practice opportunities reduced overconfidence and improved prediction accuracy.     

Examining a processing tradeoff explanation of proactive interference

Burns (1989) claims that proactive interference effects occur in paired-associate learning because of tradeoffs in relational and response-specific processing. Consistent with this claim, Burns demonstrated that free recall of critical-list responses is better in the interference condition than in the control condition. Burns’s processing trade off explanation predicts that the occurrence of this reverse-interference effect should be positively correlated with the occurrence of traditional interference effects. We present several experiments whose results are inconsistent with-this-prediction. We hypothesize that the reverse-interference effect is a list-length effect. The results of a final experiment, contrasting the predictions of the list-length and processing trade off explanations, support the list-length explanation.     

Memory for objects and their locations: the role of the hippocampus in retention of object-place associations

Computational models of hippocampal function have suggested that the hippocampus is involved in the formation and storage of arbitrary associations. Previous studies have shown that rats with hippocampal lesions are impaired in object-place associative learning. However, few studies have examined the role of the hippocampus in the retention of previously learned arbitrary associations. In the present study, male Long-Evans rats with either cortical control or hippocampal lesions were tested on a task measuring the retention of previously learned arbitrary associations using an object-place paired-associate task. To assess retention, each animal was trained on the paired-associate task for 360 trials, then received a lesion, and was retested to examine retention of the previously learned associations. The results indicate that all rats learned the task prior to surgery. Following surgery, rats with cortical control lesions were not impaired in the retention of object-place associations. In contrast, hippocampal lesions resulted in an initial deficit in retention of the paired-associate task followed by recovery. Therefore, the hippocampus may play a role in the retrieval of previously learned arbitrary association.