Item-specific encoding produces an additional benefit of directed forgetting: Evidence from intrusion errors.

List-method directed forgetting involves encoding 2 lists, between which half of the participants are told to forget List 1. When participants are free to study however they want, directed forgetting impairs List 1 recall and enhances List 2 recall in the forget group compared with a control remember group. In a large-scale experiment, the current work demonstrated that when item-specific encoding instructions were enforced during learning, directed forgetting impaired List 1 recall, but it did not enhance List 2 recall. This pattern was found regardless of whether encoding was incidental or intentional. Whenever directed forgetting did not enhance List 2 recall, it nevertheless reduced cross-list intrusions. These results indicate that directed forgetting can help differentiate memories from one another, thereby reducing intrusions from irrelevant competing memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amount of postcue encoding predicts amount of directed forgetting.

In list-method directed forgetting, participants are cued to intentionally forget a previously studied list (List 1) before encoding a subsequently presented list (List 2). Compared with remember-cued participants, forget-cued participants typically show impaired recall of List 1 and improved recall of List 2, referred to as List 1 forgetting and List 2 enhancement. In 3 experiments, we examined how amount of postcue encoding influences directed forgetting. Two results emerged dissociating List 1 forgetting from List 2 enhancement. First, an increase in amount of postcue encoding led to an increase in List 1 forgetting but did not affect List 2 enhancement. Second, the forget cue influenced all List 1 items but affected only early List 2 items. A 2-mechanism account of directed forgetting is suggested, according to which List 1 forgetting reflects reduced accessibility of List 1 items, and List 2 enhancement arises from a reset of encoding processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

The role of retrieval practice in directed forgetting.

Three experiments tested the possibility that retrieval-induced forgetting is responsible for directed forgetting with the list method. In Experiments 1 and 2, additional List 2 retrieval practice was given to determine whether this would increase directed forgetting. In Experiment 1 all items came from a single category, and in Experiment 2 unrelated words were used. In Experiment 3 additional List 2 study accompanied List 2 retrieval practice. There was no evidence that List 2 retrieval practice, with or without additional List 2 study, affected the magnitude of directed forgetting. It was argued that retrieval-induced forgetting could not account for these results. Accounts with greater viability include retrieval strategy disruption and a modified version of the dissociation hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative interference and premorbid adjustment in schizophrenia.

The effects of associative interference on the verbal learning performance of 60 male process and reactive schizophrenics and 30 normals were studied using a mixed list with high and moderate interlist interference and new learning conditions. Schizophrenics made more errors than normals in the interference conditions but not in the new learning. Reactive schizophrenics made as many errors as the process group with high interference but significantly fewer under moderate interference. Process schizophrenics gave significantly more List 1 intrusions in List 2 learning than reactives or normals. Results support predictions from the qualitative differences theory of cognitive deficit. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A contextual change account of the directed forgetting effect.

The authors propose that the costs and benefits of directed forgetting in the list method result from an internal context change that occurs between the presentations of 2 lists in response to a "forget" instruction. In Experiment 1 of this study, costs and benefits akin to those found in directed forgetting were obtained in the absence of a forget instruction by a direct manipulation of cognitive context change. Experiment 2 of this study replicated those findings using a different cognitive context manipulation and investigated the effects of context reinstatement at the time of recall. Context reinstatement reduced the memorial costs and benefits of context change in the condition where context had been manipulated and in the standard forget condition. The results are consistent with a context change account of directed forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directed forgetting: Comparing pictures and words.

The authors investigated directed forgetting as a function of the stimulus type (picture, word) presented at study and test. In an item-method directed forgetting task, study items were presented 1 at a time, each followed with equal probability by an instruction to remember or forget. Participants exhibited greater yes–no recognition of remember than forget items for each of the 4 study–test conditions (picture–picture, picture–word, word–word, word–picture). However, this difference was significantly smaller when pictures were studied than when words were studied. This finding demonstrates that the magnitude of the directed forgetting effect can be reduced by high item memorability, such as when the picture superiority effect is operating. This suggests caution in using pictures at study when the goal of an experiment is to examine potential group differences in the magnitude of the directed forgetting effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A model for interference and forgetting.

A new model for interference and forgetting is presented. The model is based on the search of associative memory (SAM) theory for retrieval from long-term memory by J. G. Raaijmakers and R. M. Shiffrin, see record 1981-20491-001). It includes a contextual fluctuation process that enables it to handle time-dependent changes in retrieval strengths. That is, the contextual retrieval strength is assumed to be proportional to the overlap between the contextual elements encoded in the memory trace and the elements active at the time of testing. It is shown that the model predicts a large number of phenomena from the classical interference literature. These include the basic results concerning retroactive inhibition, proactive inhibition, spontaneous recovery, independence of List 1 and List 2 recall, Osgood's transfer and retroaction surface, simple forgetting functions, the use of recognition measures, and the relation between response accuracy and response latency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intentional forgetting is easier after two "shots" than one.

Three experiments evaluated whether the magnitude of the list-method directed forgetting effect is strength dependent. Throughout these studies, items were strengthened via operations thought to increase context strength (spaced presentations) or manipulations thought to increment the item strength without affecting the context strength (processing time and processing depth). The assumptions regarding which operations enhance item and context strength were based on the "one-shot" hypothesis of context storage (K. J. Malmberg & R. M. Shiffrin, 2005). The results revealed greater directed forgetting of strong items compared with weak items, but only when strength was varied via spaced presentations (Experiment 3). Equivalent directed forgetting was observed for strong and weak items when strengthening operations increased item strength without affecting the context strength (Experiments 1 and 2). These results supported the context hypothesis of directed forgetting (L. Sahakyan & C. M. Kelley, 2002). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response faults on word association as a function of associative difficulty and of affective connotation of the words.

Conducted an experiment to adjudicate among factors influencing response faults on the word association technique. Associative difficulty and affective connotation were manipulated independently as dimensions of verbal stimuli. 60 words, varying in associative difficulty and in affective connotation, were administered as a word association test to undergraduate Ss: 20 high and 20 low scorers on a test of neuroticism. Half of each group were tested under stress and half under standard conditions. The affective connotation of the words elicited lengthened latencies and "misremembering" on retest, whereas associative difficulty evoked lengthened latencies and forgetting of response on retest. Stress and neuroticism did not influence word association. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context and mediators in a theory of distributed associative memory (TODAM2).

Recent findings on the interactions of item and associative information have necessitated a revision of TODAM (a theory of distributed associative memory). Item information underlies the memory for individual items or events, and associative information allows one to relate or associate 2 separate items or events. The troublesome findings are the differential forgetting of item and associative information (item recognition falls off over retention intervals, whereas associative information does not) and the differential emphasis results (greater attention to items hurts pair recognition, but greater attention to pairs does not affect item recognition). The addition of context and mediators enables TODAM to account for these interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directed Forgetting in Incidental Learning and Recognition Testing: Support for a Two-Factor Account.

Instructing people to forget a list of items often leads to better recall of subsequently studied lists (known as the benefits of directed forgetting). The authors have proposed that changes in study strategy are a central cause of the benefits (L. Sahakyan & P. F. Delaney, 2003). The authors address 2 results from the literature that are inconsistent with their strategy-based explanation: (a) the presence of benefits under incidental learning conditions and (b) the absence of benefits in recognition testing. Experiment 1 showed that incidental learning attenuated the benefits compared with intentional learning, as expected if a change of study strategy causes the benefits. Experiment 2 demonstrated benefits using recognition testing, albeit only when longer lists were used. Memory for source in directed forgetting was also explored using multinomial modeling. Results are discussed in terms of a 2-factor account of directed forgetting. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Impairing Forgetting by Preventing New Learning and Memory.

Two causes of forgetting have been promulgated: memory trace decay and retroactive interference. The authors show that forgetting is an active process requiring both new learning and memory. In the present 1Lymnaea model system, prevention of new learning of a conflicting association, inhibition of memory consolidation, or Right Pedal Dorsal 1 soma ablation, which blocks LTM formation, are all potent means to prevent forgetting. Thus procedures that alter the ability to learn or form memory of a new conflicting aerial respiratory association prevent forgetting of a learned associative behavior. These results are the 1st demonstration in any model system that forgetting requires the soma of a single neuron. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directed forgetting in implicit and explicit memory tests: A comparison of methods.

Directed forgetting has been studied by instructing Ss to forget either (1) an initial list or (2) individually selected words. Differential encoding was hypothesized to be responsible for word-method directed forgetting, and retrieval inhibition for list-method directed forgetting. In Exps 1 and 2, directed forgetting was observed in recognition with the word method but not with the list method. Release from directed forgetting occurred in final recall after recognition but only with the list method. These results are interpreted in terms of a theoretical framework that integrates distinctive-relational processing theory with revised generation-recognition theory. In Exps 1–3, predictions from that framework were generally well supported on implicit and explicit retention tests that provided the same stimulus conditions. Consistent with processing theory, list-method directed forgetting was absent on data-driven or conceptually driven implicit tests, and word-method directed forgetting was absent on data-driven implicit tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theoretical implications of extralist probes for directed forgetting.

In 5 experiments, the authors examined the influence of associative information in list-method directed forgetting, using the extralist cuing procedure (Nelson & McEvoy, 2005). Targets were studied in the absence of cues, but during retrieval, related cues were used to test their memory. Experiment 1 manipulated the degree of resonant connections from associates of the target back to the target. Experiment 2 varied the degree of connectivity of associates of the target. Experiment 3 varied the size of the associative neighborhood of the target. Experiment 4 varied the direct target-to-cue strength, and Experiment 5 varied the indirect strength between the cue and the target. Reliable directed forgetting impairment emerged in all experiments. Furthermore, directed forgetting reduced the effects of the associates contributing to the target activation strength (Experiments 1–2), and it also reduced the effects of the associates contributing to the cue–target intersection strength (Experiments 3–5). Together, these results support the context account and challenge the inhibitory interpretation of directed forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The crucial role of postcue encoding in directed forgetting and context-dependent forgetting.

People can intentionally forget previously studied material if, after study, a forget cue is provided and new material is learned. It has recently been suggested that such list-method directed forgetting arises because the forget cue induces a change in internal context and causes context-dependent forgetting of the studied material (L. Sahakyan & C. M. Kelley, 2002). The authors compared directed forgetting and context-dependent forgetting by examining whether, like a forget cue, a change in internal context needs subsequent learning of new material to be effective. Participants studied an item list and, after study, received a remember cue or a forget cue or their internal context was changed through an imagination task. In each condition, half the participants learned a second list, and the other half fulfilled an unrelated distractor task. Both the forget cue and the change in internal context induced forgetting of the first list only when learning of the second list was interpolated. These results suggest that postcue encoding of new material is crucial for both directed forgetting and (some forms of) context-dependent forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of cue dependency on item and source memory.

The authors investigated the cue dependency of source and item memory. Individuals listened to words spoken by a man or a woman and later determined whether a test word was previously presented by a man or by a woman, or whether it was a new word. Cue dependent effects were assessed by presenting test words with (a) the same voice (match condition) that originally presented the word, (b) a different but familiar voice (mismatch condition), (c) a novel test voice (novel condition), and (d) no test voice (control condition). Compared with the control condition, source recollection was facilitated in matching-context conditions, disrupted in mismatching-context conditions, and not affected in novel test conditions. By contrast, item recognition was not affected by the match–mismatch manipulation but was significantly worse in novel test voice conditions. The authors propose an associative source interference view to account for the voice match–mismatch effects observed in source recollection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Curved saccade trajectories reveal conflicting predictions in associative learning.

We report how the trajectories of saccadic eye movements are affected by memory interference acquired during associative learning. Human participants learned to perform saccadic choice responses based on the presentation of arbitrary central cues A, B, AC, BC, AX, BY, X, and Y that were trained to predict the appearance of a peripheral target stimulus at 1 of 3 possible locations, right (R), mid (M), or left (L), in the upper hemifield. We analyzed as measures of associative learning the frequency, latency, and curvature of saccades elicited by the cues and directed at the trained locations in anticipation of the targets. Participants were trained on two concurrent discrimination problems A+R, AC+R, AX+M, X+M and B+L, BC+L, BY+M, Y+M. From a connectionist perspective, cues were predicted to acquire associative links connecting the cues to the trained outcomes in memory. Model simulations based on the learning rule of the Rescorla and Wagner (1972) model revealed that for some cues, the prediction of the correct target location was challenged by the interfering prediction of an incorrect location. We observed that saccades directed at the correct location in anticipation of the target curved away from the location that was predicted by the interfering association. Furthermore, changes in curvature during training corresponded to predicted changes in associative memory. We propose that this curvature was caused by the inhibition of the incorrect prediction, as previously has been suggested with the concept of distractor inhibition (Sheliga, Riggio, & Rizzolatti, 1994; Tipper, Howard, & Houghton, 2000). The paradigm provides a new method to examine memory interference during associative learning. (PsycINFO Database Record (c) 2011 APA, all rights reserved)