The hippocampus and memory of verbal and pictorial material

Recognition of words and kaleidoscope pictures showed a double dissociation of left and right hippocampal activity using magnetic source imaging (MSI). MSI has advantages over alternative imaging techniques that measure hemodynamic changes for identifying regional changes in brain activity in real time and on an individual subject basis without the need for image subtraction. In this study, lists of words or kaleidoscope pictures were presented for memorization followed by tests of list items and foils during which brain activity was recorded. There was greater activation in the left than the right hippocampus with abstract nouns (e.g., relief) and greater activation in the right than the left hippocampus with kaleidoscope pictures. This dissociation was evident on a case by case basis. This study demonstrates the specialization of the two medial temporal lobe (MTL) regions, including the hippocampi, for mnemonic processing of verbal and pictorial items that are difficult to encode verbally.     

Recall of common and distinctive features of verbal and pictorial stimuli

Subjects first rated similarity of verbal and of pictorial stimuli. The same pairs of stimuli were presented again, without one common component and one distinctive component. Subjects were asked to recall the missing components and identify them as common or distinctive. The results show that components encoded as common are recalled relatively better than components encoded as distinctive, and the difference in recall is significantly greater in verbal than in pictorial stimuli.     

Recognition memory for pictorial stimuli: biasing effects of stimulus emotionality

The possibility that stimulus emotionality might influence recognition bias in a long-term memory task was studied with respect to both the valence and arousal dimensions of emotion. For this purpose, we used 108 International Affective Picture System pictures that were representative of all regions of this two-dimensional space. Signal detection theory analysis was applied using A'and B' D as discrimination and bias measures, respectively. In general, the results showed that greater discrimination was accompanied by a response bias that was more conservative for pleasant and for unarousing pictures than for unpleasant and for arousing ones. These results provide new evidence in connection with the emotion-induced recognition bias in long-term memory performance.     

Emotional enhancement of immediate memory: Positive pictorial stimuli are better recognized than neutral or negative pictorial stimuli

We examined emotional memory enhancement (EEM) for negative and positive pictures while manipulating encoding and retrieval conditions. Two groups of 40 participants took part in this study. Both groups performed immediate implicit (categorization task) and explicit (recognition task) retrieval, but for one group the tasks were preceded by incidental encoding and for the other group by intentional encoding. As indicated by the sensitivity index (d'), after incidental encoding positive stimuli were easier to recognize than negative and neutral stimuli. Participants' response criterion was more liberal for negative stimuli than for both positive and neutral ones, independent of encoding condition. In the implicit retrieval task, participants were slower in categorizing positive than negative and neutral stimuli. However, the priming effect was larger for emotional than for neutral stimuli. These results are discussed in the context of the idea that the effect of emotion on immediate memory enhancement may depend on the intentionality to encode and retrieve information.     

An analysis of the visual component in recognition memory for verbal stimuli

Forty Ss were given a continuous recognition memory test in which each word was presented twice, either in the same print or in different print on the two occasions. The results showed that (a) recognition performance was facilitated to a small but statistically significant extent in the same-print condition and that (b) Ss could reliably report first presentation print for recognized items for at least 1^1/2 rain. In a second experiment, the stimuli used were nonsense strings of. from five to seven letters instead of words. This manipulation increased the same-print advantage in recognition but reduced Ss’ ability to report first print form. The results indicate that information about the physical features of verbal stimuli is retained in a visual code that is partially’ or wholly independent of the verbal code for the same stimuli. The results are inconsistent with the conclusion that the visual code is stored only as a dependent attribute of the verbal code in memory.     

Encoding the world around us: Motor-related processing influences verbal memory

It is known that properties of words such as their imageability can influence our ability to remember those words. However, it is not known if other object-related properties can also influence our memory. In this study we asked whether a word representing a concrete object that can be functionally interacted with (i.e., high-manipulability word) would enhance the memory representations for that item compared to a word representing a less manipulable object (i.e., low-manipulability word). Here participants incidentally encoded high-manipulability (e.g., CAMERA) and low-manipulability words (e.g., TABLE) while making word judgments. Using a between-subjects design, we varied the depth-of-processing involved in the word judgment task: participants judged the words based on personal experience (deep/elaborative processing), word length (shallow), or functionality (intermediate). Participants were able to remember high-manipulability words better than low-manipulability words in both the personal experience and word length groups; thus presenting the first evidence that manipulability can influence memory. However, we observed better memory for low- than high-manipulability words in the functionality group. We explain this surprising interaction between manipulability and memory as being mediated by automatic vs. controlled motor-related cognition.     

Intent to remember briefly presented human faces and other pictorial stimuli enhances recognition memory

Since the early days of psychology, researchers have investigated whether or not intending to remember information affects subsequent memory performance. The literature contains methodological issues and empirical contradictions, with ambiguous effects. In five experiments, a total of 576 participants viewed a rapid series of pictorial stimuli under either incidental- or intentional-memory conditions. Although the methodology was stringent, intent to remember consistently enhanced recognition memory. Recognition was enhanced even when participants viewed a picture of a human face, of an ape face, or of a bird for as little as 0.5-1.0 sec, with no interstimulus interval between it and the next picture. Rehearsal, depth of processing, and attentional allocation are discussed to explain how people might intentionally encode pictorial information to enhance their subsequent recognition memory performance.     

Constraints on effective pictorial and verbal elaboration

Three experiments investigated the conditions under which pictures facilitate learning. In Experiment 1, confusing verbal relationships were supplemented with pictures that illustrated the key concepts in each verbal relationship (base pictures), illustrated the key concepts in more elaborate arbitrary relationships (pictures of arbitrary elaborations), or illustrated the key concepts in ways that helped clarify the verbal relationships (pictures of explanatory elaborations). All three types of pictures facilitated the retention of the verbal relationships, although pictures of explanatory elaborations were superior to other types of visual illustrations. In Experiment 2, the facilitative effects of base pictures depended on a schematically unique illustration of the key concepts in a single image. In Experiment 3, picture facilitation effects were constrained by the type of verbal elaborations that accompanied the pictures. Specifically, base pictures and pictures of arbitrary elaborations did not facilitate the retention of confusing verbal relationships that were elaborated with explanatory information, and actually interfered with the retention of those explanatory elaborations. The implications of these results are discussed.     

Picturing survival memories: Enhanced memory after fitness-relevant processing occurs for verbal and visual stimuli

Recent studies have shown that processing words according to a survival scenario leads to superior retention relative to control conditions. Here, we examined whether a survival recall advantage could be elicited by using pictures. Furthermore, in Experiment 1, we were interested in whether survival processing also results in improved memory for details. Undergraduates rated the relevance of pictures in a survival, moving, or pleasantness scenario and were subsequently given a surprise free recall test. We found that survival processing yielded superior retention. We also found that distortions occurred more often in the survival condition than in the pleasantness condition. In Experiment 2, we directly compared the survival recall effect between pictures and words. A comparable survival recall advantage was found for pictures and words. The present findings support the idea that memory is enhanced by processing information in terms of fitness value, yet at the same time, the present results suggest that this may increase the risk for memory distortions.     

Visual similarity effects on short-term memory for order: The case of verbally labeled pictorial stimuli

Four experiments examined the effect of visual similarity on immediate memory for order. Experiments 1 and 2 used easily nameable line drawings. Following a sequential presentation in either silent or suppression conditions, participants were presented with the drawings in a new, random order and were required to remember their original serial position. In Experiment 3, participants first learned to associate a verbal label with an abstract matrix pattern. Then they completed an immediate memory task in which they had to name the matrices aloud during presentation. At recall, the task required remembering either the order of the matrices or the order of their names. In Experiment 4, participants learned to associate nonword labels with schematic line drawings of faces; the phonemic similarity of the verbal labels was also manipulated. All four experiments indicate that the representations supporting performance comprise both verbal and visual features. The results are consistent with a multiattribute encoding view.     

Interference in memory for pictorial information

Subjects studied either faces composed from visual features or verbal facts composed from concepts. Recognition times were increased for both faces and facts when they were composed of elements that occurred in multiple study items. In Experiment 1 the interfering effect of other study items was much larger for verbal facts than for faces. This difference was largely eliminated in Experiment 2 where care was taken to control the features by which the faces were encoded. Experiment 2 also showed that verbal information could interfere with pictorial information and vice versa. However, this cross-modality interference was much weaker than within-modality interference. The data are consistent with the ACT theory in which pictorial material and verbal material are stored together in an abstract propositional network. The subnode model (Anderson, Language, memory, and thought, Hillsdale, N. J.: Lawrence Erlbaum, 1976) can account for the greater within- than cross-modality interference.     

Age and forgetting rate with pictorial stimuli

The rate of forgetting standardized line drawings of common objects was assessed in groups of young (M age = 22 years) and older (M age = 70.5 years) subjects. The two groups forgot equal quantities of pictorial stimuli over successive intervals of 10 min, 2 hr, and 48 hr, after being matched for original learning. In contrast, the older subjects showed the expected age decrement in reproduction of geometric designs from memory. These findings indicate that aging does not affect retention of pictures when differences in learning and retrieval abilities are controlled.     

Free recall and complexity of pictorial stimuli

In order to explore variables underlying primacy and recency effects in free recall of pictorial material, norms were developed using 120 subjects who rated the vividness and complexity of slides. Two experiments were then run in which two levels of each of these variables (extreme high and low ratings) were factorially combined. In the first experiment 24 subjects were shown three mixed lists, two short and one long (consisting of materials of all four combinations of vividness and complexity), and in the second experiment 12 subjects were shown four pure lists (consisting of materials of a single type). Analysis of variance showed list length in the mixed list experiment and complexity in both experiments to be strong determinants of recall. Greatest recall was for items of low complexity in short lists. Weak, but statistically significant, serial position effects were evident, particularly for less complex items. The effects of primacy and recency seem to decrease with increasing complexity of visual materials, perhaps because of the greater difficulty in rehearsing more complex pictures either verbally or iconically.     

Mental imagery and pictorial memory

Previous research has failed to show consistent effects upon memory performance of individual differences in the use of mental imagery. A test of pictorial memory was devised which varied the ease with which the stimulus patterns could be verbally encoded. A factor analysis related performance in this task to a variety of other individual characteristics. The recall of material which could not be readily verbalized defined a factor within the solution which showed significant loadings of age and performance in the Progressive Matrices, but not of subjective ratings of the vividness of experienced imagery. The recall of material which could be readily verbalized did not contribute to the factorial structure of the results. It was concluded that the two sorts of pictorial material are remembered in quite different ways.