The role of semantic knowledge and working memory in everyday tasks

We present a single case study of a patient, HG, who was severely impaired on routine everyday tasks, such as cleaning his teeth and preparing a cup of tea. We used the Action Coding System developed by Schwartz et al. (1991) to provide quantitative and qualitative measures of his performance in a number of experimental manipulations: (a) with task-congruent objects only, (b) with task-congruent objects and semantic distractors, (c) with a set of written commands to follow, (d) when he was given one command at a time, (e) when he was shown how the task should be performed before starting himself, and (f) when the task was divided into smaller subgoals. In general, the majority of HG's errors were step omissions, perseverations, sequence errors, and semantic errors. These semantic errors are particularly interesting since HG was able to name, gesture to, and define all the objects when they were presented in isolation or in task-congruent arrays. We suggest that semantic errors may arise for a number of reasons: (1) impaired access from semantic memory to a network representing action schema, (2) degradation of stored schema, and (3) behavior that is abnormally driven by the goal, by preceding actions, or by salient objects rather than by an appropriate association between these elements in working memory.     

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.     

Episodic generation can cause semantic forgetting: Retrieval-induced forgetting of false memories

In two experiments, we tested whether false recognition and false recall were prone to retrieval-induced forgetting, using the retrieval practice paradigm (Anderson, Bjork, & Bjork, 1994). Participants encoded lists of cue-target word pairs associated with a nonpresented, critical theme word and then engaged in retrieval practice for half of the word pairs from half of the lists. As expected, unpracticed targets from practiced lists were recognized (Experiment 1) and recalled (Experiment 2) less well than those from unpracticed lists. In addition, false recognition and false recall of critical items associated with practiced lists was lower than false recognition and false recall of items associated with unpracticed lists. We argue that false memories are prone to inhibitory mechanisms engendered by the retrieval practice paradigm. The results are consistent with the claim that semantically activated critical themes interfere with the episodic retrieval of list words and that inhibition decreases the activation level of these interfering memory representations during retrieval practice.     

Target strength and retrieval-induced forgetting in semantic recall

Retrieval-induced forgetting (RIF) occurs when practice of a memory item impairs retrieval of related, unpracticed items. Here, we demonstrated that RIF in semantic memory is retrieval dependent. University students either studied (7 × 8 = 56) or retrieved (7 × 8 = ?) the answers to a set of multiplication problems for 40 blocks and then were tested on their addition counterparts (7 + 8 = ?). For the retrieval practice group, but not the study practice group, response time for the multiplication-practiced addition facts was about 100 msec slower, relative to control addition problems, in the first of five postpractice addition blocks. Subsequent blocks of addition were interleaved with retrieval blocks of all the multiplication counterparts, which permitted measurement of RIF for the control addition problems after only a single retrieval of their multiplication counterparts. The control problems presented RIF in excess of 200 msec, much larger than the RIF observed after massive practice. This is consistent with the hypothesis that inhibition of competitors should be weaker when target strength is high than when target strength is only moderate (Anderson, 2003; Norman, Newman, &; Detre, 2007). The evidence that RIF in semantic retrieval is both retrieval dependent and weaker following massive target practice than following moderate target practice provides strong support for inhibition-based theories of RIF.     

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.     

The role of intentional forgetting in employee selection

The authors examined the effects of forbidden information on the employee-selection process. They presented the participants with 4 applicants for the position of cashier-stockperson. One of the applicants (the Target Applicant) provided a mixture of forbidden and job-relevant information; the remaining applicants gave no forbidden information. Some of the participants were told before they reviewed the applicants what types of information were to be considered as forbidden, and they were instructed to disregard any such information in the applications. The remaining participants were not aware of the presence of the forbidden information, nor were they instructed to disregard such information. The participants who were instructed to disregard the forbidden information rated the Target Applicant more favorably than did those who were not aware of its presence. Moreover, those in the disregard condition recalled less of the forbidden information and more of the job-relevant information about the Target Applicant than did those in the no-instruction condition. These data patterns support laboratory-based studies on intentional forgetting.     

The role of inhibitory control in the production of misinformation effects

Recent research has indicated a link between retrieval-induced forgetting and the production of misinformation effects (J. Saunders & M. D. MacLeod, 2002). The mechanism underlying this relationship, however, remains unclear. In an attempt to clarify this issue, the authors presented 150 participants with misinformation under conditions designed to promote the activation of inhibitory control during the retrieval of information about a target event. A modified retrieval practice paradigm that used the independent probe method pioneered by M. C. Anderson and B. A. Spellman (1995) revealed that misinformation effects emerged only where misinformation had been introduced about items that had been subject to 1st-order, 2nd-order, or cross-category inhibition. By contrast, misinformation effects failed to emerge where inhibitory processing had not been activated. These findings are discussed in terms of inhibitory control, memory malleability, and their implications for the interviewing of eyewitnesses.     

The role of forget-cue salience in list-method directed forgetting

Research suggests that manipulating the wording of the forget cue in list-method directed forgetting affects the magnitude of directed forgetting both in younger children (Aslan, Staudigl, Samenieh, & Bauml, in press) and in older adults (Sahakyan, Delaney, & Goodmon, 2008). This occurs when the forget cue overemphasises the importance of forgetting in the current context. The present experiment investigated whether de-emphasising forgetting affected the magnitude of list-method directed forgetting in college adults. Some participants received overt forget cues that explicitly instructed them to forget earlier studied items, whereas others received covert forget cues that implied forgetting by emphasising selective remembering (e.g., “you will only need to remember some of the items”). Results indicated equivalent directed forgetting for both types of cues. However, regardless of the type of cue received, participants who reported using specific forgetting strategies in response to the forget cue showed directed forgetting, whereas those that reported doing nothing did not show any effects. The results underscore that successful directed forgetting requires engagement of controlled processes.     

The role of forget-cue salience in list-method directed forgetting

Research suggests that manipulating the wording of the forget cue in list-method directed forgetting affects the magnitude of directed forgetting both in younger children (Aslan, Staudigl, Samenieh, & Bauml, in press) and in older adults (Sahakyan, Delaney, & Goodmon, 2008). This occurs when the forget cue overemphasises the importance of forgetting in the current context. The present experiment investigated whether de-emphasising forgetting affected the magnitude of list-method directed forgetting in college adults. Some participants received overt forget cues that explicitly instructed them to forget earlier studied items, whereas others received covert forget cues that implied forgetting by emphasising selective remembering (e.g., "you will only need to remember some of the items"). Results indicated equivalent directed forgetting for both types of cues. However, regardless of the type of cue received, participants who reported using specific forgetting strategies in response to the forget cue showed directed forgetting, whereas those that reported doing nothing did not show any effects. The results underscore that successful directed forgetting requires engagement of controlled processes.     

When stereotype knowledge prevents retrieval-induced forgetting

In the present study, we examined the effects of stereotypes and the typicality of traits in retrieval-induced forgetting (RIF). The participants in the experiment practiced half of the high-typicality, low-typicality or control traits associated with the name of a stereotype (athlete, scientist) or with the name of a person (Mikel, Jon). With the person name the high-typicality, low-typicality or control traits produced no evidence of stereotype activation. The traits were processed as independent features and generated RIF both immediately and at a one-week interval. Stereotype activation during encoding facilitated the integration of high-typicality traits, avoiding RIF in immediate and one-week recall. Moreover, both high-typicality and low-typicality traits benefited from stereotypes in one-week recognition. These findings show that previous knowledge contributes to integrate stereotypic traits that would otherwise compete for retrieval, thus producing RIF.     

The role of semantic knowledge in retrieval from episodic long-term memories: Implications for a model of retrieval

Two experiments were conducted, using a paired-associate recall reaction time paradigm, to assess the role semantic knowledge plays in retrieval of long-term episodic memories. In Experiment I, word frequency and meaningfulness were manipulated; high-frequency stimuli led to significantly longer reaction times, while meaningfulness had no significant effect. In Experiment II, the role of the distribution of preexperimental associates of the stimulus was further investigated by comparing retrieval time when the stimulus had either a high- or low-strength primary associate; the former resulted in longer reaction times. The implications of these results for a model of retrieval were discussed. Exhaustive search models were found inadequate, but viable parallel and serial self-terminating models were developed. In both of these models, retrieval time is a function of strength of the correct associate, relative to total strength of a restricted set of semantic associates of the stimulus.     

The role of intentional forgetting in reducing children's retroactive interference.

Preschool and kindergarten children's retention of stories was examined in the presence of interfering information and instructions to forget. Children learned 2 stories and, 24 hr later, were asked to recall the 1st or 2nd story learned. Some of the children were instructed, either following acquisition or just prior to the retention test, to forget the 2nd, or interfering, story. A model was used to isolate storage and retrieval effects, and the results showed that (a) retroactive interference affected both storage- and retrieval-based forgetting rates for the younger children but only storage-based forgetting rates for the older children, (b) intentional forgetting reduced retroactive interference primarily by attenuating storage-based forgetting regardless of age, (c) intentional forgetting instructions were effective only at acquisition for preschoolers but at both acquisition and retention for kindergarteners, and (d) all children recalled the to-be-forgotten story as well as they recalled the to-be-remembered story. These results are interpreted in terms of reorganization and distinctiveness effects in storage.     

The role of semantic information in episodic retrieval

In two experiments, subjects studied lists of categorized words and then were tested for recognition of those words. Response time for a test word was speeded whenever the immediately preceding test word was from the same category. This was true even for test words (lures) from categories never studied. Thus it is argued that semantic information not present at the time of study affected retrieval. This finding is discussed with respect to the distinction between episodic and semantic memories.     

The role of inhibitory control in behavioral and physiological expressions of toddler executive function

A total of 81 toddlers (24-27 months of age) participated in a biobehavioral investigation of inhibitory control. Maternal report measures of inhibitory control were related to laboratory tasks assessing inhibitory abilities under conditions of conflict, delay, and compliance challenge as well as toddler verbal ability. In addition, unique variance in inhibitory control was explained by task-related changes in brain electrical activity at lateral frontal scalp sites as well as concurrent inhibitory task performance. Implications regarding neural correlates of executive function during early development and a central organizing role of inhibitory processing during toddlerhood are discussed.     

The role of inhibitory control in children's cooperative behaviors during a structured puzzle task

This study examined the role of inhibitory control (measured by Stroop interference) in children’s cooperative behaviors during a structured puzzle task. The sample consisted of 250 8-, 10-, and 12-year-olds (117 girls and 133 boys) attending classrooms in three primary schools in Northern Italy. Children individually completed an elaborated Stroop task, were paired with classmates into 125 dyads, and were observed during a 10-min puzzle task. Results confirmed that interaction partners exhibited similar levels of cooperative behaviors, and the cooperative behaviors of children predicted changes in the cooperative behaviors of their partners throughout the puzzle task. Cooperative behaviors of each interaction partner were predicted by the child’s own inhibitory control as well as the inhibitory control of the partner. Findings are discussed within a developmental contextual framework.     

The role of inhibitory control in the development of human figure drawing in young children

We investigated the role of inhibitory control in young children’s human figure drawing. We used the Bear–Dragon task as a measure of inhibitory control and used the classification system devised by Cox and Parkin to measure the development of human figure drawing. We tested 50 children aged between 40 and 64 months. Regression analysis showed that inhibitory control predicted development in human figure drawing even after the effect of age was excluded. These data suggest that inhibitory control plays a role in the development of children’s drawing and imply a relation between the executive functions and representational change.     

Assessing the inhibitory account of retrieval-induced forgetting with implicit-memory tests

Five experiments examined whether retrieval-induced-forgetting effects are observed for implicit tests of memory. In each experiment participants first studied category-exemplar paired associates, then practiced retrieval for a subset of items from a subset of categories before finally completing memory tests for all the studied items. In standard fashion, inhibition was measured as the performance difference of unpracticed items from practiced categories and unpracticed items from unpracticed categories. Across the 5 experiments poorer performance for unpracticed items was seen in conceptual implicit memory (category generation and category matching) but not in perceptual implicit memory (stem completion, perceptual identification). Thus, retrieval-induced-forgetting effects are limited to tests of conceptual memory.     

A progress report on the inhibitory account of retrieval-induced forgetting

Remembering and forgetting reflect fundamentally interdependent processes in human memory (Bjork, 2011). This interdependency is particularly apparent in research on retrieval-induced forgetting, which has shown that retrieving a subset of information can cause the forgetting of other information (Anderson et al. Journal of Experimental Psychology: Learning, Memory, & Cognition 20:1063-1087, 1994). According to one prominent theoretical account, retrieval-induced forgetting is caused by an inhibitory process that acts to resolve competition during retrieval. Specifically, when cues activate competing, contextually inappropriate responses, those responses are claimed to be inhibited in order to facilitate the retrieval of target responses (Anderson Journal of Memory and Language 49: 415-445, 2003; Levy & Anderson Trends in Cognitive Sciences 6: 299-305, 2002; Storm, 2011b). Interest in retrieval-induced forgetting has grown steadily over the past two decades. In fact, a search of the abstracts at the 5th International Conference on Memory (ICOM, York University, 2011) revealed 40 presentations specifically mentioning "retrieval-induced forgetting," and nearly twice that number referring to the concept of inhibition. Clearly, researchers are interested in the empirical phenomenon of retrieval-induced forgetting, and inhibition is gaining increasing attention as a mechanism involved in memory. The goal of the present progress report is to critically review the inhibitory account of retrieval-induced forgetting and to provide direction so that future research can have a more meaningful impact on our understanding of human memory.