Low Imagery Words Research Articles

Verbal Paired Associates and the Hippocampus: The Role of Scenes.

It is widely agreed that patients with bilateral hippocampal damage are impaired at binding pairs of words together. Consequently, the verbal paired associates (VPA) task has become emblematic of hippocampal function. This VPA deficit is not well understood and is particularly difficult for hippocampal theories with a visuospatial bias to explain (e.g., cognitive map and scene construction theories). Resolving the tension among hippocampal theories concerning the VPA could be important for leveraging a fuller understanding of hippocampal function. Notably, VPA tasks typically use high imagery concrete words and so conflate imagery and binding. To determine why VPA engages the hippocampus, we devised an fMRI encoding task involving closely matched pairs of scene words, pairs of object words, and pairs of very low imagery abstract words. We found that the anterior hippocampus was engaged during processing of both scene and object word pairs in comparison to abstract word pairs, despite binding occurring in all conditions. This was also the case when just subsequently remembered stimuli were considered. Moreover, for object word pairs, fMRI activity patterns in anterior hippocampus were more similar to those for scene imagery than object imagery. This was especially evident in participants who were high imagery users and not in mid and low imagery users. Overall, our results show that hippocampal engagement during VPA, even when object word pairs are involved, seems to be evoked by scene imagery rather than binding. This may help to resolve the issue that visuospatial hippocampal theories have in accounting for verbal memory.

The effect of word imagery on priming effect under a preconscious condition: An fMRI study

Semantic priming is affected by the degree of association and how readily a word is imagined. In the association effect, activity in the perisylvian structures including the bilateral inferior frontal gyrus, the left middle temporal gyrus, and the supramarginal gyrus was correlated. However, little is known about the brain regions related to the effect of imagery word under the preconscious condition. Forty word pairs for high (HA)‐, low (LA)‐, and nonassociation (NA), nonword (NW) conditions were presented. Each 40 association word pairs (HA and LA) included 20 high (HI) and 20 low (LI) imagery prime stimuli, using a visually presented lexical decision task. A trial consisted of 30 ms prime, 30 ms mask, 500 ms probe, and 2–8 s stimulus onset asynchrony. Brain activation was measured using functional magnetic resonance imaging during word discrimination. Behavioral data indicated that the shortest response time (RT) was given for HA words, followed by LA and NA, and NW showed the longest RT (P < 0.01). RT was faster in HI than LI within HA, but not LA conditions (P < 0.01). Functional neuroimaging showed that differential brain regions for high imagery (HI) and low imagery (LI) words within low prime‐target word association were observed in the left precuneus, left posterior cingulate gyrus, and right cuneal cortex. The present findings demonstrate that the effect of the degree of imagery on semantic priming occurs during the early stage of language processing, indicating an “automatic imagery priming effect.” Our paradigm may be useful to explore semantic deficit related to imagery in various psychiatric disorders. Hum Brain Mapp 35:4795–4804, 2014. © 2014 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.

Effect of High or Low Imagery on Auditory Hallucinatory Content in Individuals Scoring High in Schizotypy

The present study examined the occurrence, and content, of auditory hallucinatory experiences in non-clinical participants scoring high or low in schizotypy. Participants listened to 10 one-minute recordings of white noise, some of which contained embedded high or low imagery words, and were asked to record any words that they heard. Results showed that high scorers on the unusual experiences scale of the Oxford-Liverpool Inventory of Feelings and Experiences showed a bias toward making hallucinatory reports of a low imagery type than of a high imagery type, but there were no significant differences for low UE scorers. Low scorers in impulsive nonconformity made more low imagery hallucinatory reports than high imagery reports. The results suggest a bias toward more hallucinatory reports of low imagery words.

Influence of word class proportion on cerebral asymmetries for high- and low-imagery words

It has been claimed that the typical RVF/LH advantage for word recognition is reduced or eliminated for imageable, as compared to nonimageable, nouns. To determine whether such word-class effects vary depending on the stimulus list context in which the words are presented, we varied the proportion of high- and low-image words presented in a lateralized lexical decision task (0, 25, 50, 75, or 100% high image). Although the RVF/LH advantage for high-image words was unaltered by word-class proportion, a significant linear trend was obtained for the low-image words such that the RVF/LH advantage increased as the proportion of low-image words increased. We discuss the implications of these findings for models of how lexical processing is distributed across hemispheres.

Word imageability and N400 in an incidental memory paradigm

High imagery words are memorized better than low imagery words. To examine how these words are processed at encoding, event-related potentials (ERPs) were recorded in an incidental memory paradigm. Frequency-matched high and low imagery words (45 words each) were presented in a random order on a computer screen. Twelve university students were asked to rate the imageability of a word's referent on a five-point scale. High imagery words elicited a larger N400 than low imagery words did. The N400 was more left-lateralized for low imagery words than for high imagery words, suggesting that some neural generators (probably in the right hemisphere) were not involved in the processing of low imagery words. Difference waveforms showed that the N400 was followed by a second negativity (N800), which was also larger for high imagery words and had a scalp distribution similar to that of the N400. Subsequent free recall showed a classical imagery effect that high imagery words were recalled better than low imagery words. These results suggest that the superiority of high imagery words over low imagery words in incidental memory results from more extensive activation of a semantic network distributed across the left and right hemispheres, the latter of which probably deals with imagery-related information that is not activated by low imagery words.

The emergent generation effect and hypermnesia: Influences of semantic and nonsemantic generation tasks.

The generation effect is moderated by experimental design, affecting recall in within-subjects designs but typically not in between-subjects designs. However, N. W. Mulligan (2001) found that the generation effect emerged over repeated recall tests in a between-subjects design, calling into question the generality of this limiting condition. In addition, the generate condition but not the read condition produced hypermnesia (increased recall over tests). The present experiments demonstrate that semantic-based (semantic-associate and category-associate) generation tasks produce this pattern of results whereas nonsemantic (letter transposition, rhyme, word fragment) generation tasks do not. Thus, the emergent generation effect appears to be a byproduct of semantic elaboration rather than a direct product of generation. In addition, high- and low-imagery words produced equivalent hypermnesia and emergent generation effects, arguing against a mediating role for imagistic encoding. Finally, there is no evidence of an emergent generation effect for nonwords, another traditional limiting condition of the generation effect.

Right hemisphere contributions to the comprehension of low-imagery words

A priming experiment, with normal university students as subjects, was used to investigate whether the right cerebral hemisphere contributes to the comprehension of low-imagery words. Each hemisphere's access to semantic representations of low-imagery words was gauged by comparing responses to low-imagery targets preceded by associated low-imagery primes (e.g., BELIEF-IDEAL) with responses to the same targets when they were preceded by unrelated primes (e.g., FATE-IDEAL). All primes and targets were independently projected to the left or right visual fields (LVF or RVF), and temporally separated by a stimulus onset asynchrony of 250 ms. There was a clear RVF advantage in response speed and accuracy measures, confirming the left hemisphere's advantage in processing low-imagery words. Nonetheless, the priming effects provided evidence that the right hemisphere contributes to the comprehension of low-imagery words, as primes projected to the RVF equally facilitated responses to associated targets subsequently appearing in either visual field. In contrast, primes directed to the LVF did not facilitate responses to associated targets projected to the LVF or RVF. The results suggest that low-imagery words projected to the left hemisphere activated low-imagery associates in both hemispheres to an equivalent degree, whereas low-imagery primes directed to the right hemisphere failed to activate low-imagery associates in either hemisphere. Like Kounios and Holcomb's (1994) study of event-related response potentials evoked by abstract and concrete words, the findings indicate that while the left hemisphere is the primary processor of low-imagery/abstract words, the right hemisphere plays a subsidiary role in the comprehension of these words.

Right hemisphere contributions to the comprehension of low-imagery words

Right hemisphere contributions to the comprehension of low-imagery words

Interhemispheric Communication Is Via Direct Connections

Two priming experiments, using normal university students as subjects, independently projected low imagery primes and concrete target words to the left or right visual fields (LVF or RVF) to examine the merits of three spreading activation models of interhemispheric communication: (i) callosal relay of a semantically encoded prime; (ii) transfer of products activated as a result of the spread of activation; and (iii) direct connections between the hemispheres. The first experiment temporally separated pairs by a stimulus onset asynchrony (SOA) of 250 ms and obtained strong support for the direct connections model. Priming effects were obtained only when the prime was projected to the RVF and the target to the LVF. The pattern of priming effects suggested that low imagery words projected to the left hemisphere can activate concrete associates in the right hemisphere via direct callosal connections between the two. In the second experiment, the SOA was increased to 450 ms. This time, RVF–RVF priming was obtained along with RVF–LVF priming. The findings are interpreted within a modification of Bleasdale's (1987) framework, where abstract/low imagery words and concrete/high imagery words are represented in separate subsystems in the left hemisphere lexicon. Support was also found for the view that the left hemisphere is comprised of a complex network of abstract and concrete words, while the right hemisphere operates as a subsidiary word processor, subserving linguistic processing with a limited, special purpose lexicon comprised of associative connections between concrete, imageable words (e.g., Zaidel, 1983a; Bradshaw, 1980). Interhemispheric communication in the priming procedure appears to occur at the semantic level, via direct connections between the hemispheres.

The effects of multimodality stimulation on hemispheric alpha asymmetries of aphasic and normal subjects

Abstract Hemispheric alpha asymmetries of normal males, normal females, and male aphasics were observed from anterior and posterior placement sites for recall and recognition of multimodality (auditory and visual) presented high and low imagery words and during resting conditions. No significant differences were observed during the resting condition between groups. Males were not found to have hemispheric asymmetries for any of the stimulus or task conditions. Females showed lower alpha power for the low imagery words compared to the high imagery words. Aphasic males were found to have significantly less alpha power in the right compared to the left hemisphere across conditions and tasks. A significant group × hemisphere × imagery interaction revealed significantly less alpha power in the left hemisphere (although not as low as the right) for low imagery words compared to the high imagery words for the aphasic subjects. This finding suggests greater involvement of the left hemisphere in processing multimodality information in aphasics that has not been reported for unimodality information (Moore 1989a, Moore and Lux 1987). Behavioural responses were found to be effected by group classification, task condition, and imagery value.

Learning disabled and average readers' working memory and comprehension: does metacognition play a role?

The present study investigates (a) whether learning disabled readers' working memory deficits that underlie poor reading comprehension are related to a general system, and (b) whether metacognition contributes to comprehension beyond what is predicted by working memory and word knowledge. To this end, performance between learning and disabled (N = 60) and average readers (N = 60) was compared on the reading comprehension, reading rate, and vocabulary subtests of the Nelson Skills Reading Test, Sentence Span test composed of high and low imagery words, and a Metacognitive Questionnaire. As expected, differences between groups in working memory, vocabulary, and reading measures emerged, whereas ability groups were statistically comparable on the Metacognitive Questionnaire. A within-group analysis indicated that the correlation patterns between working memory, vocabulary, metacognition, and reading comprehension were not the same between ability groups. For predicting reading comprehension, the metacognitive questionnaire best predicted learning disabled readers' performance, whereas the working memory span measure that included low-imagery words best predicted average achieving readers' comprehension. Overall, the results suggest that the relationship between learning disabled readers' generalised working memory deficits and poor reading comprehension may be mediated by metacognition.

Paired-Associate Learning and Recall of High and Low Imagery Words: Moderating Effects of Hypnosis, Hypnotic Susceptibility Level, and Visualization Abilities

Relationships between recall of low and high imagery paired-associate (P-A) words and hypnotic susceptibility, and the influence of hypnosis on recall as moderated by hypnotic level were examined. Subjects were assessed on 2 hypnotic susceptibility scales [Harvard Group Scale of Hypnotic Susceptibility; Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C)]. Forty-one low (0-4 SHSS:C) and 41 highly (9-12 SHSS:C) hypnotizable college students were assigned to 1 of 4 experimental groups: waking-hypnosis, hypnosis-waking, waking-waking, or hypnosis-hypnosis. Recall was significantly better for high than low imagery words. In the more sensitive within-subjects design, high hypnotizables recalled more P-A words during hypnosis than waking, and lows did not differ. In the between-subjects design, hypnotic level was not a moderator of performance during hypnosis. Low hypnotizables recalled more words in the within-subjects design. Visualization ability was a poor moderator of imagery-mediated learning. High imagery recall correlated significantly with Marks's (1973) Vividness of Visual Imagery Questionnaire (.25) and Paivio and Harshman's (1983) Individual Differences Questionnaire (IDQ) Verbal scale (.29), but not with the IDQ Imagery scale, the Mental Rotations Test (Vandenberg & Kuse, 1973), or the revised Minnesota Paper Form Board Test (Likert & Quasha, 1941).

Event-related potentials and recognition memory: the effects of word imagery value

Event-related potentials (ERPs) were recorded from 11 subjects during a recognition memory task. Subjects were auditorily presented with 160 target words and, after about 10 min, they were engaged in a recognition task. Subjects were required to determine on each of 320 trials if the word was ‘new’ (never before presented) or ‘old’ (heard previously). In the recognition test, 160 target words and 160 non-target words were used as stimuli. To assess the effect of word imagery value, 160 stimuli (80 target and 80 non-target) were high imagery words (HI) and the remaining 160 stimuli were low imagery words (LI). Word frequency was balanced across target and non-target words. Results showed that the old/new effect was reflected by a negative component (belonging to the N400 family, Cz maximum) which was larger for new words in the 400–700 ms range. The imagery effect was also present in the 250–550 ms range of the N400, which was larger for HI stimuli. The imagery effect was present at 400–550 ms only for target words. These results confirmed the hypothesis that negative components as N400, could reflect processes occurring during the memory retrieval of items.

Why does imagery improve memory?

Abstract Evidence over the last 15 years has suggested that dual (imagery and verbal) coding explanations of concreteness effects in memory for word lists do not generalise well to memory for sentences and paragraphs. In contrast, an alternative framework based on relative differences in relational and distinctive processing has been shown to account for the effects of imagery and concreteness in these contexts and others. This paper describes recent research on free and cued recall of word lists and evaluates it with respect to the two models. The evidence suggests that whereas dual processing systems may be involved in the encoding of verbal materials, dual memory codes are insufficient to explain concreteness effects in recall. Better memory for high-as compared to low-imagery words depends on the use of paradigms that facilitate inter-item relational processing, independent of whether or not imagery is involved.

Hemispheric alpha asymmetries of aphasic and normal subjects: Results from recognition and recall tasks using visually presented words of high and low imagery

Abstract Hemispheric alpha asymmetries of normal males, normal females, and male aphasics were observed from anterior and posterior placement sites for recall and recognition of visually presented high and low imagery words, and during resting conditions. No significant differences were observed during the resting conditions between groups. However, during visual presentation of words the aphasics demonstrated significantly less alpha in the right hemisphere, while no differences were observed for the normal subjects. Both fluent and non-fluent aphasics demonstrated right hemisphere alpha suppression across stimulus and task conditions. The non-fluent aphasics demonstrated lower overall alpha power levels across hemispheres than did the fluent aphasics. Results are discussed relative to the aphasics becoming more dependent upon the processing resources of the intact right hemisphere during the course of language recovery.

Hemispheric alpha asymmetries for auditorily presented words of high and low visual imagery during tasks of recognition and recall of aphasic and normal subjects

Abstract Hemispheric alpha asymmetries of normal males, normal females, and male aphasics were observed from anterior and posterior placement sites for recall and recognition of high and low imagery words and during resting conditions. Results revealed no hemispheric asymmetries across tasks and electrode placement sites for the two normal groups. Females were found to have consistently higher mean alpha amplitude values than the normal males across conditions and tasks. Aphasic subjects, both fluent and nonfluent, demonstrated greater right hemisphere alpha suppression across tasks and conditions. No significant alpha asymmetries were found between groups during the resting condition. All subjects recognized more words than they recalled. High imagery words were more readily recognized or recalled than low imagery words. Results of the investigation are discussed relative to greater use of right hemisphere processing resources by aphasic subjects for processing linguistic information.

Why do Socratic stimuli produce hypermnesia?

Socratic stimuli, giving a description of a word without presenting the word itself, increase recall as a function of retention interval (see the studies on hypermnesia in Erdelyi, Buschke, & Finkelstein, 1977). In the present study, one lengthy recall task (20 min) or four consecutive recall trials of 5 min followed the presentation of either Socratic descriptions of words or words themselves, which were either of high or low imagery value (Experiment 1). The recall task used the impaired feedback technique (Gardiner, Passmore, Herriot, & Klee, 1977) leaving the already retrieved items unavailable during the remaining time of the recall trial or trials. The nature of the recall task did not affect recall performance, and only Socratic descriptions of high imagery words produced a recall increase. In Experiment 2, two possible sources of hypermnesia with Socratic stimuli were further explored: imagery and the generation effect. Generation failed to produce hypermnesia, while Socratic descriptions of high and low imagery words produced significant effects. Moreover, high imagery words without Socratic descriptions also led to hypermnesia. An encoding context that improves a unique semantic processing is likely to be critical for obtaining hypermnesia.

Patterns of regional cerebral blood flow related to memorizing of high and low imagery words—An emission computer tomography study

Patterns of regional cerebral blood flow were investigated in healthy volunteers who were either resting or memorizing meaningless words, abstract nouns, or concrete nouns, the latter being given either with or without an instruction to use visual imagery. Relative regional count rates were subjected to smallest space analysis (SAA) to study the structure of covariations. Memorizing of concrete nouns gave rise to the formation of a continuous correlational subspace which comprised inferior temporal and occipital regions. When concrete nouns were memorized without an imagery instruction the mean hemispheric count rate was higher on the right side, whereas the intentional use of imagery gave rise to a left preponderance. Analysis of correlational structures, however, suggests that in both cases the left hemisphere was predominantly engaged in task solution, and that the difference in hemispheric asymmetries is to be attributed to different modes of interhemispheric collaboration.

Further analysis of encoding in patients with Huntington's disease

Arguments favoring the view that derangement of normal encoding processes contributes to the memory defects of patients with Huntington's disease (HD) are supported by the finding that HD patients do not learn highly imageable words more rapidly than they learn words that are difficult to image. But other data indicating that HD patients can use verbal mediators as mnemonic aids for picture recognition question the existence of important and general encoding deficits in HD. In the first of two experiments the influence of imagery on the acquisition and recall of 14-word lists was studied using a free-recall paradigm. Both HD patients and controls learned highly imageable words more quickly and retained them better than low imagery words over a 30-min delay. The impact of imagery on learning was apparent by the first trial. In the second experiment, a modified Brown-Peterson distractor paradigm was used to assess release from proactive interference (PI). It was found that both HD patients and controls exhibited comparable release from PI following a shift in taxonomic categories. The results of both experiments question the importance of encoding deficits in the memorial dysfunctions associated with HD.

Signal detection analysis of recognition memory in depressed elderly

The purpose of this study was to examine the relationship of late-life depression to memory complaint and objective performance in a recognition memory task. Fifty-seven individuals between the ages of 58 and 88 were evaluated for depression using the Beck Depression Inventory (short form). They were then shown two stimulus lists, each consisting of high-imagery and low-imagery words. Recognition for these words was subsequently tested. Error rates and nonparametric signal detection measures were analyzed as indices of performance. Respondents gave global self-assessments of memory and, during the recognition task, also made self-ratings of performance. Depressed individuals showed more conservative response biases than nondepressed respondents, reflected in a higher false-negative error rate but a lower false-positive rate. Neither overall memory sensitivity as assessed by signal detection analysis nor self-ratings of performance were related to depression, though global memory self-ratings were. Elderly depressed individuals thus presented a pattern of greater memory complaint and unwillingness to venture responses in spite of showing small or no information-processing deficits.