Understanding or feeling? Motor and sensory processes in recall of haptic experiences

Effects of learning can show in a direct, i.e., explicit way, or they can be expressed indirectly, i.e., in an implicit way. It is investigated whether hepatic information shows implicit effect, and whether implicit haptic memory effects are based primarily on motor or on sensory memory components. In the first phase blindfolded subjects had to palpate objects in order to answer questions about the objects' distinct properties as fast as possible. In the following phase this task was repeated with the same objects and additional control items. Additionally, recognition judgements were required. Results demonstrate reliable effects of implicit memory for haptic information in terms of reaction times to old vs. new objects. Subjects who had to wear plastic gloves in the first stage showed comparable effects of repetition priming. Changing the questions--and, thus, hand movements--during the palpitation of objects known from the first stage, however, abolishes implicit memory expression. It is concluded, therefore, that implicit memory for haptic information is based on motor processes. On the other hand, explicit memory is hampered in subjects wearing gloves during the first phase, as revealed in terms of recognition performance while changing the questions about objects' properties has no effect on recognition judgements. Thus, explicit memory for haptic information seems to be based on the sensory processes when touching objects.     

Masked repetition priming hinders subsequent recollection but not familiarity: A behavioral and event-related potential study

The present study used the masked repetition priming paradigm in the study phase and the R/K paradigm in the test phase to investigate whether repetition priming can hinder recognition memory and which recognition process (familiarity or recollection) is hindered. Event-related potentials (ERPs) in the study and test phase were recorded to explore the temporal course of how repetition priming hinders subsequent recognition memory and which old/new effect (FN400 or LPC) is affected. Converging behavioral and ERP results indicated that masked repetition priming hindered subsequent recollection but not familiarity. The analysis of ERP priming effects in the study phase indicated that primed words were associated with less negative N400 and less positive LPC compared to unprimed words. The analysis of the priming effect as a function of subsequent memory revealed that only the LPC priming effect was predictive of priming effect on subsequent memory, which suggested that the “prediction-error” account might be a possible explanation of how repetition priming affects subsequent recognition memory.     

The word frequency effect in recognition memory versus repetition priming

The role of word frequency in recognition memory and repetition priming was investigated by using a manipulation of attention. In Experiment 1, the lexical decision task produced greater repetition priming for low-frequency words than for high-frequency words following either the attended or the unattended study condition. The recognition memory test, on the other hand, showed a low-frequency word advantage only following the attended study condition. Furthermore, this advantage was limited to the measure of recognition memory based on conscious recollection of the study episode. In Experiment 2, a speeded recognition memory test replicated the pattern obtained with the unspeeded recognition memory test in Experiment 1. These results argue against the view that the word frequency effects in recognition memory and repetition priming have the same origin. Instead, the results suggest that the word frequency effect in recognition memory has its locus in conscious recollection.     

Evidence that nonconscious processes are sufficient to produce false memories

Are nonconscious processes sufficient to cause false memories of a nonstudied event? To investigate this issue, we controlled and measured conscious processing in the DRM task, in which studying associates (e.g., bed, rest, awake...) causes false memories of nonstudied associates (e.g., sleep). During the study phase, subjects studied visually masked associates at extremely rapid rates, followed by immediate recall. After this initial phase, nonstudied test words were rapidly presented for perceptual identification, followed by recognition memory judgments. On the perceptual identification task, we found significant priming of nonstudied associates, relative to control words. We also found significant false recognition of these nonstudied associates, even when subjects did not recall this word at study or identify it at test, indicating that nonconscious processes can cause false recognition. These recognition effects were found immediately after studying each list of associates, but not on a delayed test that occurred after the presentation of several intervening lists. Nonconscious processes are sufficient to cause this memory illusion on immediate tests, but may be insufficient for more vivid and lasting false memories.     

Orientation-specific possibility priming for novel three-dimensional objects

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects’ picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0° to 60°. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60°–180° orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60°).     

Orientation-specific possibility priming for novel three-dimensional objects.

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects' picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0 degree to 60 degrees. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60 degrees-180 degrees orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60 degrees).     

Multiple contributions to priming effects for familiar faces: analyses with backward masking and event-related potentials

The model of face recognition by Bruce and Young postulates a pool of structural representations for familiar faces in long-term memory, so-called face recognition units (FRUs). Event-related brain potentials show early repetition priming effects for familiar faces around 250-300 ms [N250r or early repetition effect (ERE)], which are thought to reflect the activation of these FRUs. However, small N250r effects are also seen for unfamiliar faces suggesting that priming of perceptual codes (i.e., pictorial and structural codes) also contributes to early repetition effects. Using a face-familiarity task in Experiment 1, we aimed to eliminate these perceptual contributions to face priming by backward masking the prime face with a different, unfamiliar face. As expected, a repetition priming effect appeared only for familiar faces. Experiment 2 used a semantic-decision task and compared the effects of different kinds of masks that interfered with either pictorial codes or with pictorial and structural codes. Our findings indicate that both structural codes and memory representations contribute to the N250r and that unfamiliar-face masks interfere only with structural codes. Face-masks may therefore provide a useful tool to extract the pure contributions of memory representations (i.e., FRUs) to repetition priming.     

Electrophysiological correlates of exemplar-specific processes in implicit and explicit memory

The present ERP study investigated the retrieval of task-irrelevant exemplar-specific information under implicit and explicit memory conditions. Subjects completed either an indirect memory test (a natural/artificial judgment) or a direct recognition memory test. Both test groups were presented with new items, identical repetitions, and perceptually different but conceptually similar exemplars of previously seen study objects. Implicit and explicit memory retrieval elicited clearly dissociable ERP components that were differentially affected by exemplar changes from study to test. In the indirect test, identical repetitions, but not different exemplars, elicited a significant ERP repetition priming effect. In contrast, both types of repeated objects gave rise to a reliable old/new effect in the direct test. The results corroborate that implicit and explicit memory fall back on distinct cognitive representation and, more importantly, indicate that these representations differ in the type of stimulus information stored. Implicit retrieval entailed obligatory access to exemplar-specific perceptual information, despite its being task irrelevant. In contrast, explicit retrieval proved to be more flexible with conceptual and perceptual information accessed according to task demands.     

Priming and Recognition of Human Motion Patterns

Left-right orientation and size incongruence is known to affect recognition memory for objects but not object priming. In the present study, the effects of study-test changes in left-right orientation and size on old-new recognition decisions and long-term priming of human motion patterns were examined. Experiment 1 showed effects of orientation incongruence on both recognition and priming. Experiment 2 showed an effectof size incongruence on recognition memory but not on priming. It is suggested that the representations of human actions that underlie human motion priming are on a level that preserve orientation, possibly because of the importance of dynamic information for perceiving motion patterns or because encoding of human motion is governed by a body schema (e.g. Reed & Farah, 1995). In contrast, low-level metric information such as size is inconsequential to priming because priming involves identification of shape, which is not affected by size transformations. The effect of size on recognition memory, on the other hand, shows thatexplicitrecognition decisions may draw on any available episodic information, including metric attributes, to make an old new discrimination.     

Object color affects identification and repetition priming

We investigated the influence of color on the identification of both non-studied and studied objects. Participants studied black and white and color photos of common objects and memory was assessed with an identification test. Consistent with our meta-analysis of prior research, we found that objects were easier to identify from color than from black and white photos. We also found substantial priming in all conditions, and study-to-test changes in an object's color reduced the magnitude of priming. Color-specific priming effects were large for color-complex objects, but minimal for color-simple objects. The pattern and magnitude of priming effects was not influenced either by the extent to which an object always appears in the same color (i.e., whether a color is symptomatic of an object) or by the object's origin (natural versus fabricated). We discuss the implications of our findings for theoretical accounts of object perception and repetition priming.     

The mapping from sound structure to the lexicon in aphasia: evidence from rhyme and repetition priming

Two studies were conducted to explore the hypothesis that Broca's and Wernicke's aphasics have deficits arising from the processes involved in activating the lexicon from phonological form. The first study explored whether phonologically similar lexical entries differing only in their initial consonants show "rhyme priming." Results revealed that Broca's aphasics failed to show facilitation when the target was identical to the prime (i.e. identity priming) and they showed significant inhibition when targets were preceded by rhyming words. Wernicke's aphasics showed a pattern of results similar to that of normal subjects, i.e., identity priming and rhyme priming as well as significantly slower reaction-times in the rhyming condition compared to the identity condition. The second study investigated form-based repetition priming in aphasic patients at a number of intervals including when no other stimuli intervened between repeated stimuli (0 lag) or when 4, 8, or 12 stimuli intervened. Results showed that, unlike old normal subjects who showed repetition priming for both words and nonwords, both Broca's and Wernicke's aphasics showed repetition priming for word targets only. Moreover, in contrast to old normal subjects who showed a greater magnitude of priming at 0 lag for word targets, neither Broca's aphasics or Wernicke's aphasics showed priming at 0 lag. Implications of these findings are considered with respect to the hypotheses that Broca's and Wernicke's aphasics have deficits in the nature of the activation patterns within the lexicon itself and in auditory (working) memory.     

Memory for object location and route direction in virtual large-scale space

In everyday life people have to deal with tasks such as finding a novel path to a certain goal location, finding one's way back, finding a short cut, or making a detour. In all of these tasks people acquire route knowledge. For finding the same way back they have to remember locations of objects like buildings and additionally direction changes. In three experiments using recognition tasks as well as conscious and unconscious spatial priming paradigms memory processes underlying wayfinding behaviour were investigated. Participants learned a route through a virtual environment with objects either placed at intersections (i.e., decision points) where another route could be chosen or placed along the route (non-decision points). Analyses indicate first that objects placed at decision points are recognized faster than other objects. Second, they indicate that the direction in which a route is travelled is represented only at locations that are relevant for wayfinding (e.g., decision points). The results point out the efficient way in which memory for object location and memory for route direction interact.     

The role of colour in implicit and explicit memory performance

We present two experiments that examine the effects of colour transformation between study and test (from black and white to colour and vice versa, or from incorrectly coloured to correctly coloured and vice versa) on implicit and explicit measures of memory for diagnostically coloured natural objects (e.g., yellow banana). For naming and coloured-object decision (i.e., deciding whether an object is correctly coloured), there were shorter response times to correctly coloured-objects than to black-and-white and incorrectly coloured-objects. Repetition priming was equivalent for the different stimulus types. Colour transformation did not influence priming of picture naming, but for coloured-object decision priming was evident only for objects remaining the same from study to test. This was the case for both naming and coloured-object decision as study tasks. When participants were asked to consciously recognize objects that they had named or made coloured-object decisions to previously, whilst ignoring their colour, colour transformation reduced recognition efficiency. We discuss these results in terms of the flexibility of object representations that mediate priming and recognition.     

Memory for object location and route direction in virtual large-scale space

In everyday life people have to deal with tasks such as finding a novel path to a certain goal location, finding one's way back, finding a short cut, or making a detour. In all of these tasks people acquire route knowledge. For finding the same way back they have to remember locations of objects like buildings and additionally direction changes. In three experiments using recognition tasks as well as conscious and unconscious spatial priming paradigms memory processes underlying wayfinding behaviour were investigated. Participants learned a route through a virtual environment with objects either placed at intersections (i.e., decision points) where another route could be chosen or placed along the route (non-decision points). Analyses indicate first that objects placed at decision points are recognized faster than other objects. Second, they indicate that the direction in which a route is travelled is represented only at locations that are relevant for wayfinding (e.g., decision points). The results point out the efficient way in which memory for object location and memory for route direction interact.     

Effect of divided attention on explicit and implicit aspects of recall

If subjects have to form word images before spelling a word from the image, results of a repetition of the spelling test reveal a reliable priming effect: Old words can be spelled faster than comparable control words, reflecting a form of implicit memory. We investigated whether this kind of repetition priming remains stable under conditions of divided attention in the study phase. The subjects had to spell meaningful words, meaningless non-words, and non-words that were meaningful with a backward spelling direction (troper, for example). In the testing stage, recognition judgments as a form of explicit memory were required, too. Divided attention in the study phase had a negative effect on explicit memory, as revealed by performance on the recognition task, but had little effect on implicit memory, as revealed by performance on the repetition of the spelling test. A further dissociation between implicit and explicit memory showed up as meaningful words were recognized much better than non-words, whereas implicit memory was uninfluenced by the meaningfulness variable. The disadvantage of backward spellings was not reduced with non-words (like troper) spelled backwards. Finally, we analyzed the relations between spelling times and recognition judgments and found a pattern of dependency for non-words only. Generally, the results are discussed within processing-oriented approaches to implicit memory with a special emphasis on controversial findings concerning the role of attention in different expressions of memory.     

Are individual differences in masked repetition and semantic priming reliable?

Despite the robustness of semantic priming (e.g., cat–DOG), the test-retest and internal reliabilities of semantic priming effects within individuals are surprisingly low. In contrast, repetition priming (e.g., dog–DOG) appears to be far more reliable across a range of conditions. While Stolz and colleagues attribute the low reliability in semantic priming to uncoordinated automatic processes in semantic memory, their use of unmasked priming paradigms makes it difficult to fully rule out the influence of strategic processes. In the present study, we explored the reliability of semantic and repetition priming when primes were heavily masked and cannot be consciously processed. We found that masked repetition, but not semantic, priming effects showed some degree of reliability. Interestingly, skilled lexical processors (as reflected by vocabulary knowledge and spelling ability) also produced larger masked repetition priming effects.     

Repetition priming across the adult lifespan--the long and short of it

Previous reports suggest that repetition priming (i.e., enhanced processing of a stimulus after experience with that stimulus) is long lasting and impervious to the effects of age, in contrast to the pattern found with explicit memory. However, the nature of repetition priming in aged individuals remains unclear, as conflicting findings have also been reported. We used a longitudinal design to examine how repetition priming is affected by multiple stimulus repetitions (three presentations) and different delay intervals (no delay, 1 day, 1 week, and 1 month) in young adults, as well as in two groups of aging adults (young-elderly and old-elderly). Our findings extend previous reports that priming is long lasting, even when 1 month intervenes between the initial experience with an item and the subsequent priming test of that item (Cave, 1997), and is relatively impervious to the effects of age (Mitchell, et al., 1990). In addition, a more detailed characterization of priming and the effects of aging was revealed. Although priming is long lasting, remaining significant even at the month delay for all groups, it did decline over time and the rate of that decline differed with age. Both young-elderly and old-elderly groups showed a marked drop-off at 1 day, whereas young adults did not show a decline until 1 week. All groups benefited from multiple repetitions; however, this benefit disappeared at the month delay (in contrast to recognition memory, where the benefit remained significant). These findings support the assertion that repetition priming and explicit memory reflect the operation of distinct systems, and that these systems may undergo different rates of change in aging.     

联想启动与知觉启动的比较研究

采用快速命名方法探讨不同加工水平对联想启动效应的影响。被试分别在深、浅加工条件下学习一系列颜色词,然后完成颜色命名和再认任务,并设立词命名任务,以比较联想启动和知觉启动的异同。结果表明,在颜色命名任务中,深、浅加工条件下均可形成对颜色词的启动效应,但浅加工条件下的再认成绩明显低于深加工,出现了联想启动和再认的分离现象。词命名表现出与颜色命名相似的结果,但它们在有意识回忆方面仍存在一定的差异,提示知觉表征系统单独并不能支持联想启动,联想启动可能是多个记忆系统共同作用的结果。