Abstraction and perceptual individuation in primed word identification are modulated by distortion and repetition: a dissociation

One experiment investigated the effects of distortion and multiple prime repetition (super-repetition) on repetition priming using divided-visual-field word identification at test and mixed-case words (e.g., goAT). The experiment measured form-specificity (the effect of matching lettercase at study and test) for two non-conceptual study tasks. For an ideal typeface, super-repetition increased form-independent priming leaving form-specificity constant. The opposite pattern was found for a distorted typeface; super-repetition increased form-specificity, leaving form-independent priming constant. These priming effects did not depend on the study task or test hemifield for either typeface. An additional finding was that only the ideal typeface showed the usual advantage of right hemifield presentation. These results demonstrate that super-repetition produced abstraction for the ideal typeface and perceptual individuation for the distorted typeface; abstraction and perceptual individuation dissociated. We suggest that there is a fundamental duality between perceptual individuation and abstraction consistent with Tulving's (1984) distinction between episodic and semantic memory. This could reflect a duality of system or process.     

Modeling the effects of repetition and word frequency in perceptual identification

The counter model for word identification (Ratcliff & McKoon, 1997) has been challenged by recent empirical findings that performance on low-frequency words improves as the result of repetition of the words. We show that the model can accommodate this learning effect, and that it can do so without jeopardizing its explanations of the effects on word identification of a large number of other variables.     

Testing the counter model for perceptual identification: Effects of repetition priming and word frequency

The counter model for perceptual identification (Ratcliff & McKoon, 1997) differs from alternative views of word recognition in two important ways. First, it assumes that prior study of a word does not result in increased sensitivity but, rather, in bias. Second, the effects of word frequency and prior study are explained by different mechanisms. In the present experiment, study status and word frequency of target and foil were varied independently. Using a forced-choice task, we replicated the bias effect. However, we also found several interactions between frequency and prior study that are in direct conflict with the counter model. Most important, prior study of both alternatives resulted in an attenuation of the frequency effect and an increase in performance for low-frequency targets, but not for high-frequency targets. These findings suggest that the effects of frequency and prior study are not mediated by completely independent mechanisms.     

Mechanisms of facilitation in primed perceptual identification

We investigated the mechanism that produces priming in perceptual identification. In Experiment 1, subjects studied a series of compound words (e.g.,outdoor,sideline); in Experiment 2, subjects studied a series of pictures (photographs) of objects. All subjects later received perceptual identification tests in which old (primed) and new (unprimed) words (Experiment 1) or pictures (Experiment 2) were presented for varying durations and masked. In both experiments, performance for primed and unprimed stimuli was predicted essentially perfectly by a model that assumes that prior exposure to a stimulus results in increased visual information-acquisition rate when it is subsequently encountered. An ancillary purpose of Experiment 1 was to test whether or not priming occurs for recombined words (e.g.,outline); there was no evidence for such priming at any exposure duration.     

Building permanent memory codes: codification and repetition effects in word identification

The studies presented in this article investigate the memory processes that underlie two phenomena in threshold identification: word superiority over pseudowords and the repetition effect (a prior presentation of an item facilitates later identification of that item). Codification (i.e., the development of a single memory code that can be triggered even by fragmented input information) explains the faster and more accurate identification of words than pseudowords. Our studies trace the development and retention of such codes for repeated pseudowords and examine the growth and loss of the repetition effect for both pseudowords and words. After approximately five prior occurrences, words and pseudowords are identified equally accurately in two types of threshold identification tasks, suggesting codification has been completed for pseudowords. Although the initial word advantage disappears, the accuracy of identification still increases with repetitions. The facilitation caused by repetition is not affected much by spacing within a session, but drops from one day to the next, and after a delay of one year has disappeared (new and old words were identified equally well). These results suggest an episodic basis for the repetition effect. Most important, after one year, performance is equal for old pseudowords and new and old words: all these levels are superior to that for new pseudowords, suggesting that the learned codes for pseudowords are as strong and permanent as the codes for words. A model of identification is presented in which feedback from codes and episodic images in memory facilitates letter processing. An instantiation of the model accounts for the major features of the data.     

Bias in masked word identification: unconscious influences of repetition priming

The beneficial influence of a prior study episode on subsequent identification of a word includes a large bias component, revealed in the forced-choice variant of the masked word identification test. In that type of test, subjects show a preference for a studied probe over a nonstudied probe, regardless of which one matches the masked target word. The forced-choice test was used in the present experiments to test the possibility that this bias effect is due to conscious recollection. Results show that bias was strongly attenuated (1) by changes in modality between study and test, and (2) under certain conditions, by using a conceptually driven study task. The bias effect was found only when probes were orthographically similar to one another, as predicted by the counter model (Ratcliff & McKoon, 1997). These results provide strong evidence that the bias effect is not mediated by conscious recollection.     

Abstractionist versus episodic theories of repetition priming and word identification

This paper reviews research relevant to the question of whether words are identified through the use of abstract lexical representations, specific episodic representations, or both. Several lines of evidence indicate that specific episodes participate in word identification. First, pure abstractionist theories can explain short-term but not long-term repetition priming. Second, long-term repetition priming is sensitive to changes in surface features or episodic context between presentations of a word. Finally, long-term priming for pseudowords is also difficult for pure abstractionist theories to explain. Alternative approaches to word identification are discussed, including both pure episodic theories and theories in which both episodes and abstract representations play a role.     

The interaction of sentence context and perceptual analysis in word identification

The influence of sentence context on word identification has, in some interactive models, been attributed to enhanced accuracy or speed of perceptual analysis. This view is challenged by two experiments in which contextually enhanced word identification was found only when a target’s relevance to the sentence context was correlated with its presence. When this constraint was removed by using contextually relevant foils, accuracy in detecting words in normal and scrambled sentences did not differ reliably. Moreover, under conditions that constituted a negative correlation between target relevance and presence, word identification was more accurate with scrambled than with normal sentences. These results are consistent with models of sentence context effects that are based on the assumptions that (1) perceptual analysis proceeds independently of contextual analysis, and (2) the results of these analyses are integrated to determine a word’s identity.     

In defense of abstractionist theories of repetition priming and word identification

There is a great deal of interest in characterizing the representations and processes that support visual word priming and written word identification more generally. On one view, these phenomena are supported by abstract orthographic representations that map together visually dissimilar exemplars of letters and words (e.g., the lettersA/a map onto a common abstract letter codea*). On a second view, orthographic codes consist in a collection of episodic representations of words that interact in such a way that it sometimes looksas if there are abstract codes. Tenpenny (1995) contrasted these general approaches and concluded by endorsing the episodic account, arguing that no evidence demands that we posit abstract orthographic representations. This review reconsiders the evidence and argues that a variety of priming and nonpriming research strongly supports the conclusion that abstract orthographic codes exist and support priming and word identification. On this account, episodic representations are represented separately from abstract orthographic knowledge and contribute minimally to these functions.     

Semantic priming and word repetition: The two effects are both additive and interactive

The additivity of semantic priming and word repetition was tested in an auditory perceptual identification task, with a view to tease apart automatic and strategic priming mechanisms. The factors Word Repetition, Semantic Priming, and Practice interacted. Word Repetition and Semantic Priming were additive in the first half of the experiment, but not in the second half. A more detailed analysis indicated that Word Repetition was additive with automatic semantic priming but not with strategic semantic priming. Results suggested that the word-repetition effect depends in part on conscious strategic anticipation processes.Parts of this study were presented at the 25th International Congress of Psychology, Brussels, 1992, and at the 34th Tagung experimentell arbeitender Psychologen, Osnabrück, 1992     

Perspective distortion of trajectory forms and perceptual constancy in visual event identification

Previous studies have shown that people can use the information in trajectory forms to recognize visual events. A trajectory form is composed of the path of motion and the change in speed along that path. In past studies, however, only sensitivity to trajectory forms viewed from a single perspective was examined. The optical components change when an event is viewed from different perspectives, and the projected form of the trajectory is transformed. Does event recognition exhibit constancy despite these changes? In Experiment 1, participants were familiarized with five different trajectory forms viewed from a single perspective. Then the participants had to identify the same events viewed from different perspectives: from the side, at an angle, and entirely in depth. The participants exhibited perceptual constancy. Experiment 2 revealed, however, that both the change in optical components and the perspective transformations affected recognition.     

Covert operations: orthographic recoding as a basis for repetition priming in word identification

When a word is generated from a semantic cue, coincident orthographic visualization of that word may cause priming on a subsequent perceptual identification test. A task was introduced that required subjects to visualize the orthographic pattern of auditorily presented words. When used at study, this task produced a pattern of priming similar to that produced by a generate study task. When used at test, equal priming on the orthographic task was produced by read and generate study tasks but not by a generate study task that failed to invite orthographic visualization. Priming on perceptually based word identification tests that results from a generate study episode may be largely due to orthographic recoding of the target rather than to conceptual processing.     

The effect of generation on long-term repetition priming in auditory and visual perceptual identification

Perceptual implicit memory is typically most robust when the perceptual processing at encoding matches the perceptual processing required during retrieval. A consistent exception is the robust priming that semantic generation produces on the perceptual identification test (Masson & MacLeod, 2002), a finding which has been attributed to either (1) conceptual influences in this nominally perceptual task, or (2) covert orthographic processing during generative encoding. The present experiments assess these possibilities using both auditory and visual perceptual identification, tests in which participants identify auditory words in noise or rapidly-presented visual words. During the encoding phase of the experiments, participants generated some words and perceived others in an intermixed study list. The perceptual control condition was visual (reading) or auditory (hearing), and varied across participants. The reading and hearing conditions exhibited the expected modality–specificity, producing robust intra-modal priming and non-significant cross-modal priming. Priming in the generate condition depended on the perceptual control condition. With a read control condition, semantic generation produced robust visual priming but no auditory priming. With a hear control condition, the results were reversed: semantic generation produced robust auditory priming but not visual priming. This set of results is not consistent with a straightforward application of either the conceptual-influence or covert-orthography account, and implies that the nature of encoding in the generate condition is influenced by the broader list context.     

Visual events modulated by sound in repetition blindness

Repetition blindness (RB; Kanwisher, 1987) is the term used to describe people’s failure to detect or report an item that is repeated in a rapid serial visual presentation (RSVP) stream. Although RB is, by definition, a visual deficit, whether it is affected by an auditory signal remains unknown. In the present study, we added two sounds before, simultaneous with, or after the onset of the two critical visual items during RSVP to examine the effect of sound on RB. The results show that the addition of the sounds effectively reduced RB when they appeared at, or around, the critical items. These results indicate that it is easier to perceive an event containing multisensory information than unisensory ones. Possible mechanisms of how visual and auditory information interact are discussed.     

Top-down effects of semantic knowledge in visual search are modulated by cognitive but not perceptual load

Moores, Laiti, and Chelazzi (2003) found semantic interference from associate competitors during visual object search, demonstrating the existence of top-down semantic influences on the deployment of attention to objects. We examined whether effects of semantically related competitors (same-category members or associates) interacted with the effects of perceptual or cognitive load. We failed to find any interaction between competitor effects and perceptual load. However, the competitor effects increased significantly when participants were asked to retain one or five digits in memory throughout the search task. Analyses of eye movements and viewing times showed that a cognitive load did not affect the initial allocation of attention but rather the time it took participants to accept or reject an object as the target. We discuss the implications of our findings for theories of conceptual short-term memory and visual attention.     

Repetition blindness in priming in perceptual identification: Competitive effects of a word intervening between prime and target

University students named a 72-ms masked target word that was preceded by two 120-ms consecutively presented words, a prime word followed by a distractor. In Experiment 1, all words were in lowercase letters, whereas in Experiment 2, the target word was changed to uppercase letters. In both experiments there was an accuracy and latency cost (repetition blindness: RB) when the prime was the same word as the target, with the cost much less severe in Experiment 2 than in Experiment 1. A low-frequency distractor impaired target identification compared with a high-frequency distractor. Distractor frequency interacted with target frequency such that high-frequency targets preceded by low-frequency distractors had the lowest accuracy. The results are consistent with a frequency-dependent competition for access to working memory among briefly displayed words. However, there was no clear evidence that effects of target repetition on interword competition play a role in RB. The effects of a letter case change for the target are consistent with a contribution of token distinctiveness to word-order recovery in the intervening-word priming task.     

Performance benefits and costs in forced choice perceptual identification in amnesia: Effects of prior exposure and word frequency

Accuracy in identifying a perceptually degraded word (e.g., stake) can be either enhanced by recent exposure to the same stimulus or reduced by recent exposure to a similar stimulus (e.g., stare). In the present study, we explored the mechanisms underlying these benefits and costs by examining the performance of amnesic and control groups in a forced choice perceptual identification (FCPI) task in which briefly flashed words (that were identical to studied words, similar to studied words, or new) had to be identified, and two response choices were provided that differed from each other by one letter. Control participants showed a performance benefit and cost in FCPI with both high- and low-frequency words. Amnesic participants showed a benefit (but no cost) with high-frequency words and a benefit and a cost with low-frequency words. The benefit/cost pattern with low-frequency words in amnesia was obtained even when the to-be-identified stimulus in the FCPI task was eliminated (Experiment 2), suggesting that this effect was driven by processes operating at the level of the response choices. Our findings suggest that implicit memory effects in FCPI reflect the operation of multiple mechanisms, the relative contributions of which may vary with the frequency of the test stimuli. The results also highlight the need for caution in interpreting results from normal participants in the FCPI task, since those findings may reflect a contribution of explicit memory processes.