A comparison of conscious and automatic memory processes for picture and word stimuli: a process dissociation analysis

Four experiments were conducted to evaluate explanations of picture superiority effects previously found for several tasks. In a process dissociation procedure (Jacoby, 1991) with word stem completion, picture fragment completion, and category production tasks, conscious and automatic memory processes were compared for studied pictures and words with an independent retrieval model and a generate-source model. The predictions of a transfer appropriate processing account of picture superiority were tested and validated in "process pure" latent measures of conscious and unconscious, or automatic and source, memory processes. Results from both model fits verified that pictures had a conceptual (conscious/source) processing advantage over words for all tasks. The effects of perceptual (automatic/word generation) compatibility depended on task type, with pictorial tasks favoring pictures and linguistic tasks favoring words. Results show support for an explanation of the picture superiority effect that involves an interaction of encoding and retrieval processes.     

How are pictures registered in memory?

Three experiments tested the hypothesis that pictorial memory is much less dependent on rehearsal than is verbal memory. Experiment I examined incidental learning since this is assumed to reflect learning with little or no rehearsal. Following a classification task, intentional and incidental learning for pictures and for words was compared. The superiority of pictorial memory was especially marked in incidental learning. Experiment II showed that this result was not due to differences in the amount of processing required to classify pictures and words. RTs to classify words and pictures did not differ, and incidental learning was again superior for pictures. In Experiment III rehearsal opportunity was restricted by a concurrent task during presentation of word and picture lists, and the decrement was very much greater for word learning than for picture learning. It was concluded that manipulation of rehearsal opportunity has relatively little effect on pictorial memory.     

Effects of a concurrent memory task on hemispheric asymmetries in categorization

Recent research on the division of processing between the two cerebral hemispheres has often employed two concurrent tasks to investigate the dynamic nature of hemispheric asymmetries. The experiment reported here explored the effects of two concurrent high-level cognitive tasks (memory retention and semantic categorization) on the direction and magnitude of hemispheric differences in the processing of words and pictures. Subjects were required to categorize words and pictures presented to either the left visual field-right hemisphere (LVF-RH) or the right visual field-left hemisphere (RVF-LH). The categorization could be performed while holding either verbal material in memory (digit span), pictorial material in memory (serial nonsense figure recognition), or with no concurrent memory task. The effects produced hemisphere-specific, material-nonspecific interference. The verbal task removed a RVF-LH advantage at word categorization and enhanced a LVF-RH advantage on picture categorization; the pictorial task interfered with picture categorization in the LVF-RH, while enhancing a RVF-LH advantage at word categorization. The results are discussed in terms of multiple resource models of hemisphere function, capacity limitations, and the functional locus of processing required to produce various dynamic hemispheric effects.     

The fate of originally presented surface information following recall errors in sentence memory tasks

Pictures are remembered better than their names. This picture superiority effect in episodic memory has been attributed either to the greater sensory distinctiveness of pictures or to their greater conceptual distinctiveness. Weldon and Coyote (1996) tested the conceptual distinctiveness hypothesis by comparing how well pictures as opposed to words primed in two conceptual implicit memory tasks (category production and word association). They found no picture superiority in priming and concluded that the basis of the picture superiority effect must then be pictures' greater sensory distinctiveness. Using the same logic, we compared how well pictures as opposed to words primed in a perceptual implicit memory task (picture and word fragment identification). The sensory distinctiveness theory would predict that pictures should prime picture fragment identification better than words prime word fragment identification, a result we call the picture superiority in within-form priming. Across three experiments which manipulated the encoding task at study, only one showed picture superiority in within-form priming. In contrast, in all three experiments there was robust picture superiority in recall, and exposure to pictures and words at study and test produced independent effects in which both study and test exposure to pictures was more effective for recall than exposure to words. We consider how these results might be reconciled by differences in retrieval demands between recall and fragment identification.     

Episodic encoding and recognition of pictures and words: role of the human medial temporal lobes

In the present PET study, we examined brain activity related to processing of pictures and printed words in episodic memory. Our goal was to determine how the perceptual format of objects (verbal versus pictorial) is reflected in the neural organization of episodic memory for common objects. We investigated this issue in relation to encoding and recognition with a particular focus on medial temporal-lobe (MTL) structures. At encoding, participants saw pictures of objects or their written names and were asked to make semantic judgments. At recognition, participants made yes-no recognition judgments in four different conditions. In two conditions, target items were pictures of objects; these objects had originally been encoded either in picture or in word format. In two other conditions, target items were words; they also denoted objects originally encoded either as pictures or as words. Our data show that right MTL structures are differentially involved in picture processing during encoding and recognition. A posterior MTL region showed higher activation in response to the presentation of pictures than of words across all conditions. During encoding, this region may be involved in setting up a representation of the perceptual information that comprises the picture. At recognition, it may play a role in guiding retrieval processes based on the perceptual input, i.e. the retrieval cue. Another more anterior right MTL region was found to be differentially involved in recognition of objects that had been encoded as pictures, irrespective of whether the retrieval cue provided was pictorial or verbal in nature; this region may be involved in accessing stored pictorial representations. Our results suggest that left MTL structures contribute to picture processing only during encoding. Some regions in the left MTL showed an involvement in semantic encoding that was picture specific; others showed a task-specific involvement across pictures and words. Together, our results provide evidence that the involvement of some but not all MTL regions in episodic encoding and recognition is format specific.     

Pictorial superiority effects in oldest-old people

We examined memory for pictures and words in middle-age (45–59 years), young-old (60–74 years), old-old (75–89 years), and the oldest-old adults (90–97 years) in the Louisiana Healthy Aging Study. Stimulus items were presented and retention was tested in a blocked order where half of the participants studied 16 simple line drawings and the other half studied matching words during acquisition. Free recall and recognition followed. In the next acquisition/test block a new set of items was used where the stimulus format was changed relative to the first block. Results yielded pictorial superiority effects in both retention measures for all age groups. Follow-up analyses of clustering in free recall revealed that a greater number of categories were accessed (which reflects participants’ retrieval plan) and more items were recalled per category (which reflects participants’ encoding strategy) when pictures served as stimuli compared to words. Cognitive status and working memory span were correlated with picture and word recall. Regression analyses confirmed that these individual difference variables accounted for significant age-related variance in recall. These data strongly suggest that the oldest-old can utilise nonverbal memory codes to support long-term retention as effectively as do younger adults.     

Pictorial superiority effects in oldest-old people

We examined memory for pictures and words in middle-age (45-59 years), young-old (60-74 years), old-old (75-89 years), and the oldest-old adults (90-97 years) in the Louisiana Healthy Aging Study. Stimulus items were presented and retention was tested in a blocked order where half of the participants studied 16 simple line drawings and the other half studied matching words during acquisition. Free recall and recognition followed. In the next acquisition/test block a new set of items was used where the stimulus format was changed relative to the first block. Results yielded pictorial superiority effects in both retention measures for all age groups. Follow-up analyses of clustering in free recall revealed that a greater number of categories were accessed (which reflects participants' retrieval plan) and more items were recalled per category (which reflects participants' encoding strategy) when pictures served as stimuli compared to words. Cognitive status and working memory span were correlated with picture and word recall. Regression analyses confirmed that these individual difference variables accounted for significant age-related variance in recall. These data strongly suggest that the oldest-old can utilise nonverbal memory codes to support long-term retention as effectively as do younger adults.     

The development of the picture‐superiority effect

When pictures and words are presented serially in an explicit memory task, recall of the pictures is superior. While this effect is well established in the adult population, little is known of the development of this picture‐superiority effect in typical development. This task was administered to 80 participants from middle childhood to adolescence. The magnitude of the picture superiority effect increased with age. This finding is interpreted as supporting the position that pictorial superiority is contingent upon the encoding of pictorial information through two different routes.     

The picture superiority effect in associative recognition

The picture superiority effect has been well documented in tests of item recognition and recall. The present study shows that the picture superiority effect extends to associative recognition. In three experiments, students studied lists consisting of random pairs of concrete words and pairs of line drawings; then they discriminated between intact (old) and rearranged (new) pairs of words and pictures at test. The discrimination advantage for pictures over words was seen in a greater hit rate for intact picture pairs, but there was no difference in the false alarm rates for the two types of stimuli. That is, there was no mirror effect. The same pattern of results was found when the test pairs consisted of the verbal labels of the pictures shown at study (Experiment 4), indicating that the hit rate advantage for picture pairs represents an encoding benefit. The results have implications for theories of the picture superiority effect and models of associative recognition.     

Stimulus modality and working memory performance in Greek children with reading disabilities: Additional evidence for the pictorial superiority hypothesis

This study investigated the effects of stimulus presentation modality on working memory performance in children with reading disabilities (RD) and in typically developing children (TDC), all native speakers of Greek. It was hypothesized that the visual presentation of common objects would result in improved learning and recall performance as compared to the auditory presentation of stimuli. Twenty children, ages 10–12, diagnosed with RD were matched to 20 TDC age peers. The experimental tasks implemented a multitrial verbal learning paradigm incorporating three modalities: auditory, visual, and auditory plus visual. Significant group differences were noted on language, verbal and nonverbal memory, and measures of executive abilities. A mixed-model MANOVA indicated that children with RD had a slower learning curve and recalled fewer words than TDC across experimental modalities. Both groups of participants benefited from the visual presentation of objects; however, children with RD showed the greatest gains during this condition. In conclusion, working memory for common verbal items is impaired in children with RD; however, performance can be facilitated, and learning efficiency maximized, when information is presented visually. The results provide further evidence for the pictorial superiority hypothesis and the theory that pictorial presentation of verbal stimuli is adequate for dual coding.     

Exploring the superadditive effects of scent and pictures on verbal recall: An extension of dual coding theory

This research extends the dual coding theory of memory retrieval (Paivio 1969, 2007) beyond its traditional focus on verbal and pictorial information to olfactory information. We manipulate the presence or absence of olfactory and pictorial stimuli at the time of encoding (study 1) or retrieval (study 2) and measure the impact on verbal recall. After a time delay, scent enhances recall of verbal information, and scent-based retrieval cues potentiate the facilitative effect of pictures on recall. These results cannot be attributed merely to increased elaboration at the time of exposure.     

On the significance of “double encoding” for the superior recall of pictures to names

Ten-year-old children who were shown pictures of objects immediately preceded by the object's name recalled the material no better than those exposed to the names of the stimuli alone. Both conditions yielded significantly poorer retention than those in which pictures alone were presented or pictures followed by their names. A second study replicated this result. In addition this demonstrated, by a picture and name recognition task, that the effects could not be due to subjects in the “name prior to picture” condition ignoring the pictorial component. These results were interpreted as contradicting the “double encoding” explanation of the superiority of pictures to names in free recall. Parallel visual and verbal encoding of a pictured object does not facilitate retention unless the verbal cue is actively elicited from the subject by the stimulus. The implications of this result for other studies which have employed either simultaneous or sequential presentation of pictures and names are briefly discussed.     

The Relations of Visuo-Motor Conflict to Personality Traits and Cardio-Vascular Activity

This paper presents a review and critical analysis of some research findings and conclusions which seem to demonstrate that picture recognition memory is superior to verbal recognition memory. It cautions against accepting these data as evidence for two (picture-verbal) memory systems. Several alternative explanations of the picture-verbal performance discrepancy are derived from interference theory and partial learning theory. “Picture” as a stimulus category is vague and overinclusive. Recognition memory capacity varies from poor to excellent depending on the “pictures,” a fact not in harmony with a memory model employing a unitary processing mechanism for pictorial stimuli. Perceptual constancy is invoked in support of a view that is antagonistic to the implication that the human recognition memory mechanism is error free.     

Recognition hypermnesia: how to get it

Although recall hypermnesia (enhanced recall) over time with repeated testing has by now become an established empirical fact, its recognition counterpart, recognition hypermnesia, has defied clear-cut laboratory confirmation. In four studies, which relied on the retrieval component of recognition memory, it was shown that recognition memory, indexed by d', reliably improved over three successive recognition tests. The stimuli consisted of 140 cartoons, each comprising a picture and a verbal caption. Recognition memory was tested on transforms or part-forms (parts) of the original stimulus material (pictures only, verbal paraphrases of the pictures, the latent content of the cartoons, or the combination of paraphrases and latent contents). The strongest effects were obtained when the originally presented cartoons were tested on their latent (deep semantic) contents. Recognition hypermnesia for part-forms or transforms of earlier presented stimuli has potentially wide-ranging implications since real-world recognition--of faces, texts, visual scenes--usually involves recognising stimuli that are variants, not exact copies, of the originally encountered materials.     

Age-of-acquisition effects in lexical and episodic memory tasks

This paper reports four experiments on the effects of word age of acquisition in verbal tasks. In all cases, multiple-regression analysis was used to assess the relative effects of age as opposed to other potentially relevant word attributes. Experiments 1 and 2 concerned lexical memory tasks. In Experiment 1, picture naming speeds were found to be mainly determined by picture codability and name age of acquisition. In Experiment 2, it was found that when subjects produced words in response to bigram cues, early acquired target words were more likely to be produced than later acquired words, even when frequency and other word attributes were taken into account. The remaining two experiments dealt with the episodic memory tasks of free recall and recognition. No age effects were found in these tasks. It was concluded that early age of acquisition facilitates retrieval from lexical memory but has no significant effect in episodic memory tasks.     

Pictorial priming and cued recall in Alzheimer's and Huntington's disease

A picture fragment test was used to compare the priming and cued recall performances of patients with Huntington's disease (HD), patients with dementia of the Alzheimer type (DAT), and neurologically intact normal control (NC) subjects. On the pictorial priming test, subjects were asked to say "the first thing you think of" when shown incompletely drawn pictures, half of which were previously exposed to the subject during an unrelated naming task. Normal controls and HD patients, but not DAT patients, demonstrated similar increases in their ability to identify fragmented versions of previously seen pictures relative to novel pictures. These results are consistent with the previously observed pattern of preserved and impaired verbal priming ability in HD and DAT patients, respectively. The NC subjects, as expected, also demonstrated better performance on the cued recall than on the priming version of the picture fragment test, whereas the HD patients evidenced the opposite relationship on these two tasks and DAT patients were found to be equally impaired on both tests. This finding provides further support for the notion that HD patients' memory impairment is characterized primarily by an inability to initiate systematic retrieval strategies.     

Picture superiority in conceptual memory: Dissociative effects of encoding and retrieval tasks

We examined the role of encoding processes for picture superiority in explicit and conceptual-implicit memory. The nature of encoding instruction (naming or semantic categorization) yielded dissociative effects on picture and word memory on one explicit test, category-cued recall, and two conceptual-implicit tests, category-cued generation and category-cued verification. Category-cued recall was greater for pictures than for words following naming, but it did not differ for pictures and words following semantic categorization. Category-cued generation priming was greater for pictures than for words following naming, but it was greater for words than for pictures following semantic categorization. In contrast, category-cued verification priming did not differ for pictures and words following either naming or semantic categorization. Thus, picture superiority can be eliminated or reversed depending on the type of conceptual encoding task and conceptual-retrieval test.     

Recognition hypermnesia: How to get it

Although recall hypermnesia (enhanced recall) over time with repeated testing has by now become an established empirical fact, its recognition counterpart, recognition hypermnesia, has defied clear-cut laboratory confirmation. In four studies, which relied on the retrieval component of recognition memory, it was shown that recognition memory, indexed by d′, reliably improved over three successive recognition tests. The stimuli consisted of 140 cartoons, each comprising a picture and a verbal caption. Recognition memory was tested on transforms or part-forms (parts) of the original stimulus material (pictures only, verbal paraphrases of the pictures, the latent content of the cartoons, or the combination of paraphrases and latent contents). The strongest effects were obtained when the originally presented cartoons were tested on their latent (deep semantic) contents. Recognition hypermnesia for part-forms or transforms of earlier presented stimuli has potentially wide-ranging implications since real-world recognition—of faces, texts, visual scenes—usually involves recognising stimuli that are variants, not exact copies, of the originally encountered materials.     

The picture-superiority effect in category-association tests

In two experiments we examined the picture-superiority effect in the framework of the transfer-appropriate processing approach recently advocated by Roediger, Weldon, and Challis (1989). For the first time conceptual implicit-memory task is used, i.e., category association. In Experiment 1, subjects study a mixed list of pictures and words and then receive either a category-association test or a category-cued recall test, followed by a recognition test. The results show that performance on category-cued recall, recognition, and category-association tests are better when the material is studied in picture format. In Experiment 2, we show that producing a sentence with the material studied (picture or word) eliminates the picture-superiority effect in the implicit test, but does not eliminate picture superiority in the category-cued recall test. These results suggest that conceptually driven processing plays a critical role in category association and explicit tests of memory. The results are discussed in the framework of the transfer-appropriate processing approach to memory.