The influence of acoustic and semantic similarity on long-term memory for word sequences

It has been shown that short-term memory (STM) for word sequences is grossly impaired when acoustically similar words are used, but is relatively unaffected by semantic similarity. This study tests the hypothesis that long-term memory (LTM) will be similarly affected. In Experiment I subjects attempted to learn one of four lists of 10 words. The lists comprised either acoustically or semantically similar words (A and C) or control words of equal frequency (B and D). Lists were learned for four trials, after which subjects spent 20 min. on a task involving immediate memory for digits. They were then asked to recall the word list. The acoustically similar list was learned relatively slowly, but unlike the other three lists showed no forgetting. Experiment II showed that this latter paradox can be explained by assuming the learning score to depend on both LTM and STM, whereas the subsequent retest depends only on LTM. Experiment III repeats Experiment I but attempts to minimize the effects of STM during learning by interposing a task to prevent rehearsal between the presentation and testing of the word sequences. Unlike STM, LTM proved to be impaired by semantic similarity but not by acoustic similarity. It is concluded that STM and LTM employ different coding systems.     

How does acoustic similarity influence short-term memory?

This study attempts to discover why items which are similar in sound are hard to recall in a short-term memory situation. The input, storage, and retrieval stages of the memory system are examined separately. Experiments I, II and III use a modification of the Peterson and Peterson technique to plot short-term forgetting curves for sequences of acoustically similar and control words. If acoustically similar sequences are stored less efficiently, they should be forgotten more rapidly. All three experiments show a parallel rate of forgetting for acoustically similar and control sequences, suggesting that the acoustic similarity effect does not occur during storage. Two input hypotheses are then examined, one involving a simple sensory trace, the other an overloading of a system which must both discriminate and memorize at the same time. Both predict that short-term memory for spoken word sequences should deteriorate when the level of background noise is increased. Subjects performed both a listening test and a memory test in which they attempted to recall sequences of five words. Noise impaired performance on the listening test but had no significant effect on retention, thus supporting neither of the input hypotheses. The final experiments studied two retrieval hypotheses. The first of these, Wickelgren's phonemic-associative hypotheses attributes the acoustic similarity effect to inter-item associations. It predicts that, when sequences comprising a mixture of similar and dissimilar items are recalled, errors should follow acoustically similar items. The second hypothesis attributes the effect to the overloading of retrieval cues which consequently do not discriminate adequately among available responses. It predicts maximum error rate on, not following, similar items. Two experiments were performed, one involving recall of visually presented letter sequences, the other of auditorily presented word sequences. Both showed a marked tendency for errors to coincide with acoustically similar items, as the second hypothesis would predict. It is suggested that the acoustic similarity effect occurs at retrieval and is due to the overloading of retrieval cues.     

Limits of the retrieval-inhibition construct: list segregation in directed forgetting

The authors hypothesized that retrieval inhibition in list method directed forgetting could be improved by presenting a task that maximized the segregation step of the retrieval-inhibition process. In Experiment 1, they presented lists of semantically related words in a list method directed-forgetting task to maximize retrieval inhibition. Contrary to predictions, this manipulation eliminated the directed-forgetting effect. The authors further investigated the results of Experiment 1 in Experiments 2 and 3 by manipulating recall instructions and by presenting lists that contained both a categorized and an unrelated list-half. They found directed-forgetting effects for semantically related word lists when participants were asked to recall only the TBR (to-be-remembered) items but not when participants were asked to recall both the TBF (to-be-forgotten) and TBR items. They also found that directed-forgetting effects were not produced when categorized items were presented in the 1st list.     

Limits of the Retrieval-Inhibition Construct: List Segregation in Directed Forgetting

The authors hypothesized that retrieval inhibition in list method directed forgetting could be improved by presenting a task that maximized the segregation step of the retrieval-inhibition process. In Experiment 1, they presented lists of semantically related words in a list method directed-forgetting task to maximize retrieval inhibition. Contrary to predictions, this manipulation eliminated the directed-forgetting effect. The authors further investigated the results of Experiment 1 in Experiments 2 and 3 by manipulating recall instructions and by presenting lists that contained both a categorized and an unrelated list-half. They found directed-forgetting effects for semantically related word lists when participants were asked to recall only the TBR (to-be-remembered) items but not when participants were asked to recall both the TBF (to-be-forgotten) and TBR items. They also found that directed-forgetting effects were not produced when categorized items were presented in the 1st list.     

Mapping from Sound to Meaning: Reduced Lexical Activation in Broca''s Aphasics

Recent studies of lexical access in Broca's aphasics suggest that lexical activation levels are reduced in these patients. The present study compared the performance of Broca's aphasics with that of normal subjects in an auditory semantic priming paradigm. Lexical decision times were measured in response to word targets preceded by an intact semantically related prime word ("cat"-"dog"), by a related prime in which one segment was acoustically altered to produce a poorer phonetic exemplar ("c*at"-"dog"), and by a semantically unrelated prime ("ring"-"dog"). The effects of the locus of the acoustic distortion within the prime word (initial or final position) and the presence of potential lexical competitors ("cat" --> /gaet/versus "coat" --> "goat") were examined. In normal subjects, the acoustic manipulations produce a small, short-lived reduction in semantic facilitation irrespective of the position of the distortion in the prime word or the presence of a voiced lexical competitor. In contrast, Broca's aphasics showed a large and lasting reduction in priming in response to word-initial acoustic distortions, but only a weak effect of word-final distortions on priming. In both phonetic positions, the effect of distortion was greater for prime words with a lexical competitor. These findings are compatible with the claim that Broca's aphasics have reduced lexical activation levels, which may result in a disruption of the bottom-up access of words on the basis of acoustic input as well as increased vulnerability to competition between acoustically similar lexical items.     

The semantic‐similarity effect in children: Influence of long‐term knowledge on verbal short‐term memory

The present research was designed to highlight the relation between children's categorical knowledge and their verbal short‐term memory (STM) performance. To do this, we manipulated the categorical organization of the words composing lists to be memorized by 5‐ and 9‐year‐old children. Three types of word list were drawn up: semantically similar context‐dependent (CD) lists, semantically similar context‐independent (CI) lists, and semantically dissimilar lists. In line with the procedure used by Poirier and Saint‐Aubin (1995) , the dissimilar lists were produced using words from the semantically similar lists. Both 5‐ and 9‐year‐old children showed better recall for the semantically similar CD lists than they did for the unrelated lists. In the semantic similar CI condition, semantic similarity enhanced immediate serial recall only at age 9 but contributed to item information memory both at ages 5 and 9. These results, which indicate a semantic influence of long‐term memory (LTM) on serial recall from age 5, are discussed in the light of current models of STM. Moreover, we suggest that differences between results at 5 and 9 years are compatible with pluralist models of development.     

False memories are hard to inhibit: differential effects of directed forgetting on accurate and false recall in the DRM procedure

Directed forgetting research shows that people can inhibit the retrieval of words that they were previously instructed to forget. The present research applied the directed forgetting procedure to the Deese/Roediger and McDermott (DRM) recall task to determine if directed forgetting instructions have similar or different effects on accurate and false memory. After studying lists of semantically related words, some participants were told to forget those lists, whereas other participants were not. All participants were then shown additional lists to remember. Following study, all participants were asked to free recall as many of the studied words as possible, including those they were previously instructed to forget. Directed forgetting instructions inhibited the accurate recall of studied words, but not the false recall of nonstudied critical words, whether measured by a within-participant or between-participants design. Contrary to an implicit activation hypothesis, false memories survived instructions to forget. These findings were reviewed in terms of fuzzy trace theory and the activation/monitoring approach to false memory.     

Acoustic and associative coding in short-term memory

Short lists of word-digit pairs were presented to 456 college student subjects. One of the words was repeated as a memory probe either immediately after list presentation or after a short rehearsal interval. The stimulus words were either acoustically identical or associatively related (UP, DOWN). Both acoustic identity and associative relatedness produced a memory decrement which decreased with rehearsal. One interpretation of these results is that the primary memory trace is a multiple-dimension one and that, given time, subjects can recover non-acoustic information from it. The data also indicate that the “fate” over time is different for acoustically similar and associatively related items.     

Creating False Memories of Words with or without Recognition of List Items: Evidence for Nonconscious Processes

Subjects exposed to lists of semantically related words falsely remember nonstudied words that are associated with the list items (e.g., Deese, 1959; Roediger & McDermott, 1995). To determine if subjects would demonstrate this false memory effect if they were unable to recognize the list items, we presented lists of semantically related words with or without a concurrent memory load at rates of 2 s, 250 ms, or 20 ms per word (Experiment 1, between-subjects design) and 2 s or 20 ms per word (Experiment 2, within-subjects design). We found that the subjects falsely recognized semantically related nonstudied words in all conditions, even when they were unable to discriminate studied words from unrelated nonstudied words. Recognition of list items was unnecessary for the occurrence of the false memory effect. This finding suggests that this memory illusion can be based on the nonconscious activation of semantic concepts during list presentation.     

Naming and categorizing objects: Task differences modulate the polarity of semantic effects in the picture–word interference paradigm

The picture-word interference paradigm is a prominent tool for studying lexical retrieval during speech production. When participants name the pictures, interference from semantically related distractor words has regularly been shown. By contrast, when participants categorize the pictures, facilitation from semantically related distractors has typically been found. In the extant studies, however, differences in the task instructions (naming vs. categorizing) were confounded with the response level: While responses in naming were typically located at the basic level (e.g., "dog"), responses were located at the superordinate level in categorization (e.g., "animal"). The present study avoided this confound by having participants respond at the basic level in both naming and categorization, using the same pictures, distractors, and verbal responses. Our findings confirm the polarity reversal of the semantic effects--that is, semantic interference in naming, and semantic facilitation in categorization. These findings show that the polarity reversal of the semantic effect is indeed due to the different tasks and is not an artifact of the different response levels used in previous studies. Implications for current models of language production are discussed.     

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.     

Presentation duration and false recall for semantic and phonological associates

Two experiments examined false recall for lists of semantically and phonologically associated words as a function of presentation duration. Veridical recall increased with long exposure durations for all lists. For semantically associated lists, false recall increased from 20-250 ms, then decreased. There was a high level of false recall with 20 ms durations for phonologically associated lists (47 and 44% for Experiments 1 and 2, respectively), which declined as duration increased. In Experiment 2, for lists presented at 20 and 50 ms rates, false recall given zero correct recall was observed frequently, suggesting that conscious recollection of studied words was not necessary for phonological false memory. Differences between phonologically and semantically associated lists were consistent with a feature integration model based on automatic initial processing of phonetic features of words.     

Semantic component of a cross-modal Stroop-like task

Three experiments showed that the pattern of interference of single-modality Stroop tests also exists cross-modally. Distractors and targets were either pictures or auditory words. In a naming task (Experiment 1), word distractors from the same semantic category as picture targets interfered with picture naming more than did semantically unrelated distractors; the semantic category of picture distractors did not differentially affect word naming. In a categorization task (Experiment 2), this Stroop-like effect was reversed: Picture distractors from the same semantic category as word targets interfered less with word categorization than picture distractors that were semantically unrelated; the semantic category of word distractors did not differentially affect picture categorization. Experiment 3 replicated these effects when each subject performed both tasks; the task, naming or categorizing, determined the pattern of interference between pictures and auditory words. The results thus support the existence of a semantic component of a cross-modal Stroop-like effect.     

Remembering words not presented in lists: Can we avoid creating false memories?

Can subjects avoid creating false memories as outlined in Roediger and McDermott’s (1995) false recognition paradigm if they are forewarned about this memory illusion? We presented subjects with semantically related word lists, followed by a recognition test. The test was composed of studied words, semantically related nonstudied words (critical lures), and unrelated nonstudied words. One group of subjects was uninformed about the false recognition effect, a second group was urged to minimize all false alarms, and a third group was forewarned about falsely recognizing critical lures. Compared with the uninformed and cautious subjects, the forewarned subjects reduced their false alarm rate for critical lures, and they made remember and know judgments equally often for recognized studied words and critical lures. But forewarning did not eliminate the false recognition effect, as these subjects and those in the other groups made numerous false recognitions in this task.     

False memories of emotional and neutral words

This study used the Deese-Roediger-McDermott paradigm to investigate the direction and the extent to which emotional valence in semantic word lists influences the formation of false memories (FM). The experimental paradigm consisted of 1) a study phase (learning of neutral and negative lists of words semantically associated to a non-presented critical lure (CL), 2) a free recall phase, and 3) a recognition phase. Participants had to indicate whether the displayed item was "new" (new item or non-studied CL) or "old" (studied list item). CL associated with negative word lists elicited significantly more FM than CL associated with neutral word lists. This finding is in contrast to previous work showing that emotional words elicit fewer FM than neutral words. The results of our study also suggest that valence is capable of influencing emotional memory in terms of encoding and retrieval processes.     

The role of semantically related distractors during encoding and retrieval of words in long-term memory

We examined the influence of divided attention (DA) on recognition of words when the concurrent task was semantically related or unrelated to the to-be-recognised target words. Participants were asked to either study or retrieve a target list of semantically related words while simultaneously making semantic decisions (i.e., size judgements) to another set of related or unrelated words heard concurrently. We manipulated semantic relatedness of distractor to target words, and whether DA occurred during the encoding or retrieval phase of memory. Recognition accuracy was significantly diminished relative to full attention, following DA conditions at encoding, regardless of relatedness of distractors to study words. However, response times (RTs) were slower with related compared to unrelated distractors. Similarly, under DA at retrieval, recognition RTs were slower when distractors were semantically related than unrelated to target words. Unlike the effect from DA at encoding, recognition accuracy was worse under DA at retrieval when the distractors were related compared to unrelated to the target words. Results suggest that availability of general attentional resources is critical for successful encoding, whereas successful retrieval is particularly reliant on access to a semantic code, making it sensitive to related distractors under DA conditions.     

任务难度与部分线索效应

部分线索效应是指在学习一个词表后,呈现已学项目中的一部分作为回忆线索去回忆其他项目时,回忆效果反而不如没有线索组的效果好。研究通过三个实验探讨了不同任务难度的部分线索效应。结果表明：（1）在中文词表记忆中存在部分线索效应;（2）随着学习材料难度的提高由部分线索造成的提取成绩的削减量降低。这一研究结果支持了部分线索效应的策略破坏假说。     

Impulsivity,neuroticism, and caffeine: Do they have additive effects on arousal?

The personality dimensions of impulsivity and neuroticism have been linked to differences in basal arousal. The hypothesis tested was whether these personality variables and caffeine have additive effects on arousal. All subjects received three paired-associate trials on each of two neutral control lists, two lists with semantically similar stimuli, and two lists with acoustically similar stimuli. Half of the subjects received caffeine and half placebo. Although significant interactions with personality and drug condition were obtained, the ordering of the conditions was inconsistent with the assumption that the arousal performance curve is single peaked. Further, S. Schwartz's (Journal of Research in Personality, 1975, 9, 217–225) hypothesis that in paired-associate learning high arousal and low arousal subjects process semantic and physical information differentially was not supported. The general issue of how to determine whether individual differences in performance are caused by differences in arousal is discussed.     

Executive processing in free recall of categorized lists

The present study examines the cognitive processes that operate in free recall of categorized lists by manipulating semantic structure of the lists and using a dual task methodology to restrict the processes that make demands on limited-capacity resources, the central executive resources. Relying on the assumption that, in free recall of categorized lists, the search for category names is a strategic controlled process that demands executive resources, lists with different numbers of categories ranging from 2 to 6 were employed. The results showed an effect of a secondary task on retrieval in the 4- and the 6-category list conditions, but not in the 2-category list condition. In contrast to retrieval, the secondary task interference at encoding produced an effect on recall of all three types of lists. An interesting finding was that an effect on clustering was found only when interference was present at encoding, not when it was at retrieval. This finding was in line with the suggestion (Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998) that switching (shifting between different category items) rather than clustering is related to executive functioning, and suggested that clustering may be a measure of two different types of processing: (1) executive processing at encoding and (2) automatic processing at retrieval. In addition, a different pattern of results was obtained when low frequency category words were used, indicating that the frequency of category words is an important determinant in free recall of categorized lists. Overall, the present results support the two-process account of retrieval of category words (Rosen & Engle, 1997) and the view that there are fundamental differences between encoding and retrieval processes (Naveh-Benjamin, Craik, Guez, & Dori, 1998; Naveh-Benjamin & Guez, 2000).     

How does the extraversion personality trait influence false recall with the Deese–Roediger–McDermott (DRM) paradigm?

Relative to more introverted persons, extraverts have been found to exhibit better recall and recognition in a range of memory paradigms including demonstrating a superior semantic priming effect. The present study sought to establish whether this aspect of personality might be associated with the false memory paradigm developed by Deese, Roediger, and McDermott (the DRM paradigm). Lists containing semantically related words were presented to extraverts, ambiverts, and introverts. Compared to the other two groups, extraverts falsely recalled more critical lures (words that although semantically related were not in the original lists) and non-list words. The results are discussed in relation to the concept of spreading activation.