Storage and retrieval properties of dual codes for pictures and words in recognition memory.

Storage and retrieval properties of pictures and words were studied within a recognition memory paradigm. Storage was manipulated by instructing subjects either to image or to verbalize to both picture and word stimuli during the study sequence. Retrieval was manipulated by representing a proportion of the old picture and word items in their opposite form during the recognition test (i.e., some old pictures were tested with their corresponding words and vice versa). Recognition performance for pictures was identical under the two instructional conditions, whereas recognition performance for words was markedly superior under the imagery instruction condition. It was suggested that subjects may engage in dual coding of simple pictures naturally, regardless of instructions, whereas dual coding of words may occur only under imagery instructions. The form of the test item had no effect on recognition performance for either type of stimulus and under either instructional condition. However, change of form of the test item markedly reduced item-by-item correlations between the two instructional conditions. It is tentatively proposed that retrieval is required in recognition, but that the effect of a form change is simply to make the retrieval process less consistent, not less efficient.     

Memorability judgments for high- and low-frequency words

Five experiments were conducted in order to examine subjects’ judgments of the memorability of high- (HF) and low-frequency (LF) words in the context of a recognition memory task. In Experiment 1, the subjects were provided study/test experience with a list of HF and LF words prior to making memorability judgments for a new list of HF and LF items. The findings were consistent with previous evidence (Greene & Thapar, 1994; Wixted, 1992) suggesting that subjects are not explicitly aware of the greater recognition memorability of LF words. Experiments 2–5 embedded the memorability judgment task within the recognition test itself. In these experiments, the subjects consistently gave higher memorability ratings to LF items. The contrast between the pattern of results found when the subjects made their judgments at the time of list presentation (Experiment 1) and that when they made their judgments during the recognition test (Experiments 2–5) is consistent with recent evidence that even seemingly highly related metamnemonic judgments (e.g., ease of learning judgments vs. judgments of learning for the same items) may be based on very different factors if they occur at different points in the study/test cycle. The present findings are also consistent with the possibility that very rapid retrieval of memorability information for HF and LF words may affect recognition decisions and may contribute to the recognition memory word frequency effect.     

Storage and retrieval of serial-order information

In this paper I will first review some seminal work by Conrad on the storage and retrieval of serial-order information which is still very relevant today. Then I will discuss the TODAM (theory of distributed associative memory) approach to serial-order effects. I will compare the three TODAM serial-order models (the chaining model, the chunking model and the power-set model; Murdock, 1995) but concentrate on the power set model. Its original problems can be solved, but a revised and augmented version has some new problems. This paper is more of a progress report than a finished product, so the reader should be prepared to follow the twists and turns of the argument.     

Situation models and retrieval interference: pictures and words

Previous studies have found that interference in long-term memory retrieval occurs when information cannot be integrated into a single situation model, but this interference is greatly reduced or absent when the information can be so integrated. The current study looked at the influence of presentation format-sentences or pictures-on this observed pattern. When sentences were used at memorisation and recognition, a spatial organisation was observed. In contrast, when pictures were used, a different pattern of results was observed. Specifically, there was an overall speed-up in response times, and consistent evidence of interference. Possible explanations for this difference were examined in a third experiment using pictures during learning, but sentences during recognition. The results from Experiment 3 were consistent with the organisation of information into situation models in long-term memory, even from pictures. This suggests that people do create situation models when learning pictures, but their recognition memory may be oriented around more "verbatim", surface-form memories of the pictures.     

Learning and retrieval rate of words presented auditorily and visually

Mode of presentation (visual or auditory) of a multitrial free recall test is stressed as an important factor in improving the diagnosis of certain neurological patients. For further use in neuropsychological research, an experiment was carried out using normal subjects, in which the effects of presentation mode and order of modality were investigated. There were no differential effects of these variables on several parameters, such as the number of words recalled and the learning curve. The time needed for the responses in immediate recall was the same in both auditory and visual conditions. In delayed recall, however, the interresponse times were significantly shorter when words had been presented auditorily than when presented visually. The results are discussed in light of further application in the field of neuropsychology.     

Storage and retrieval processes in unlearning

Memory & Cognition - A revised interference theory interpretation of unlearning is presented which is based on an explicit storage-retrieval model. The theory holds that the first and second...     

Event-related brain potentials dissociate repetition effects of high-and low-frequency words

Event-related brain potentials (ERPs) were recorded while subjects detected nonwords interspersed among sequences of words of high or low frequency of occurrence. In Phase 1, a proportion of the words were repeated after six intervening items. In Phase 2, which followed after a break of approximately 15 min, the words were either repeats of items presented in the previous phase or new. Unrepeated low-frequency words evoked larger N400 components than did high-frequency items. In Phase 1, this effect interacted with repetition, such that no frequency effects were observed on N400s evoked by repeated words. In addition, the post-500-msec latency region of the ERPs exhibited a substantial repetition effect for low-frequency words, but did not differentiate unrepeated and repeated high-frequency words. In Phase 2, ERPs evoked by "old" and "new" high-frequency words did not differ in any latency region, while those evoked by old and new low-frequency words differed only after 500 msec. The interactive effects of frequency and repetition suggest that these variables act jointly at multiple loci during the processing of a word. The specificity of the post-500-msec repetition effect for low-frequency words may reflect a process responsive to a discrepancy between words' intra and extraexperimental familiarity.     

Storage and retrieval processes in sentence memory

Two experiments investigated how much time Ss take to verify a sentence with respect to a set of subject-verb-object (SVO) propositions they had learned. Three triplets of SVOs provided differing degrees of equivocation, including (1) unique SVOs, (2) a V with 3 SOs, and (3) an SV with 3 Os. A general class of models was proposed regarding the representation of prepositional trees in memory and an algorithm by which a probe tree might be verified against a set of trees in memory. In Expt I, verification times were least for Condition (1), slower and equal for Conditions (2) and (3). In Expt II, a fourth condition, an SO with 3 Vs, produced verification times as slow as those in Condition (3). Of several models considered, the closest-fitting one assumed parallel search processes proceeding simultaneously from S, V, and O positions of the probe, scanning through memory trees structered according to the HAM (Human Associative Memory) theory of Anderson and Bower.     

Factors modulating the effect of divided attention during retrieval of words

In this study, we examined variables modulating interference effects on episodic memory under divided attention conditions during retrieval for a list of unrelated words. In Experiment 1, we found that distracting tasks that required animacy or syllable decisions to visually presented words, without a memory load, produced large interference on free recall performance. In Experiment 2, a distracting task requiring phonemic decisions about nonsense words produced a far larger interference effect than one that required semantic decisions about pictures. In Experiment 3, we replicated the effect of the nonsense-word distracting task on memory and showed that an equally resource-demanding picture-based task produced significant interference with memory retrieval, although the effect was smaller in magnitude. Taken together, the results suggest that free recall is disrupted by competition for phonological or word-form representations during retrieval and, to a lesser extent, by competition for semantic representations.     

Feedforward and feedback consistency effects for high- and low-frequency words in lexical decision and naming

In three experiments, we examined feedforward and feedback consistency effects in word recognition. Feedforward consistency is the degree to which a word's pronunciation is consistent with that of similarly spelled words, and feedback consistency refers to whether there is more than one way to spell a pronunciation. Previously, Stone, Vanhoy, and Van Orden (1997) reported feedforward and feedback consistency effects for low-frequency words in a lexical decision task. We investigated the effect of feedforward and feedback consistency for both high- and low-frequency words in lexical decision and naming. In both tasks, we found that feedforward and feedback inconsistent words were processed more slowly than consistent words, regardless of word frequency. These findings indicate that both types of consistency are involved in visual word recognition.     

The effects of search criteria and retrieval cue availability on memory for words

The effects of search criteria upon recall performance following a word classification task were investigated. Rival hypotheses were tested, one based on the number of cues available at retrieval and the other on the amount of processing carried out during classification. After being presented with two-component category names, subjects classified words on the basis of either category membership or the number of semantic components the words shared with a target category, and then they received an unexpected recall test. Experiment 1 favored an amount-of-processing explanation, but it was felt that redundancy in the stimulus materials might invalidate this conclusion. Experiment 2 confirmed this suspicion and clearly supported an explanation in terms of retrieval cue availability. The notion of partial semantic processing of words is discussed, and it is argued that the number of congruent encodings formed during classification can be used as an index of elaboration and subsequent memory performance.     

Direct comparison of episodic encoding and retrieval of words: an event-related fMRI study

Functional magnetic resonance imaging (fMRI) was used to compare directly episodic encoding and retrieval. During encoding, subjects studied visually presented words and reported via keypress whether each word represented a pleasant or unpleasant concept (intentional, deep encoding). During the retrieval phase, subjects indicated (via keypress) whether visually presented words had previously been studied. No reliable differences were found during the recognition phase for words that had been previously studied and those that had not been studied. Areas preferentially active during encoding (relative to retrieval) included left superior frontal cortex, medial frontal cortex, left superior temporal cortex, posterior cingulate, left parahippocampal gyrus, and left inferior frontal gyrus. Regions more active in retrieval than encoding included bilateral inferior parietal cortex, bilateral precuneus, right frontal polar cortex, right dorsolateral prefrontal cortex, and right inferior frontal/insular cortex.     

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.     

Repetition and laterality effects on recognition memory for words and pictures*

Recognition memory for a list of words was tested by presenting a series of items with Ss instructed to make positive responses to targets (list items) and negative responses to distractors (nonlist items). The test items were either words or pictures, and they were presented tachistoscopically either to the left or right visual field. The results showed mean response latencies to be generally faster for stimuli presented to the right visual field. Response times were faster for target and distractor stimuli on their second test presentations than on initial tests, but this effect was much larger for targets. Repetitions were shown to decrease the amount of time necessary to execute the stimulus encoding and initial retrieval stages of recognition. This was also true, although to a lesser extent, if different stimulus forms (words or pictures) were used on the two tests. Subsequent recognition stages, including memory search and decision processes. were apparently independent of test stimulus form.     

Storage and retrieval of addition facts: The role of number comparison

It is proposed that arithmetical facts are organized in memory in terms of a principle that is unique to numbers—the cardinal magnitudes of the addends. This implies that sums such as 4 + 2 and 2 + 4 are represented, and searched for, in terms of the maximum and minimum addends. This in turn implies that a critical stage in solving an addition problem is deciding which addend is the larger. The COMP model of addition fact retrieval incorporates a comparison stage, as well as a retrieval stage and a pronunciation stage. Three tasks, using the same subjects, were designed to assess the contribution of these three stages to retrieving the answers to single-digit addition problems. Task 3 was the addition task, which examined whether reaction times (RTs) were explained by the model; Task 1 was a number naming task to assess the contribution of the pronunciation stage; Task 2 was a magnitude comparison task to assess the contribution, if any, of the comparison stage. A regression equation that included just expressions of these three stages was found to account for 71% of the variance. It is argued that the COMP model fits not only the adult RT data better than do alternatives, but also the evidence from development of additional skills.     

Effects of distorted auditory and of rhyming cues on retrieval of tip-of-the-tongue words by poets and nonpoets

Auditory cues (the target word distorted by a low-pass filter) and rhyming cues act as retrieval aids for people who have a word on the tip of their tongue. Parallels between the tip-of-thetongue phenomenon (TOT) and the perception of well-put passages of poetry are also discussed. It is argued that the effects of these poetic passages derive in part from the engagement of TOT-like processes. In support of this hypothesis, poets (poetry appreciators) are shown to be more aware of being helped by TOT retrieval cues than are nonpoets (poetry nonappreciators); however, the retrieval cues do not differentially influence successful recall of TOT words by poets and nonpoets.     

Effects of oral cortisol treatment in healthy young women on memory retrieval of negative and neutral words

Studies in rodents have demonstrated that glucocorticoids enhance memory consolidation but impair delayed memory retrieval. Similar findings have been reported in humans. Emotional items are better remembered than neutral items. However, it is unknown if emotional valence influences the effects of cortisol on retrieval. In this double-blind crossover study, 16 healthy women learned a wordlist containing 15 neutral and 15 negative words. Delayed recall was tested 5h later. Cortisol administered before recall testing significantly reduced retrieval (p<.01). Exploratory follow-up analysis revealed that cortisol significantly impaired retrieval of negative words (p<.01), while having no significant effect on neutral words (p=.47). The current findings could suggest that emotional material is especially sensitive to the memory modulating effects of stress hormones.