Retrospective Prime Reliance: A Flexible Retrospective Mechanism for Semantic Priming in Visual Word Recognition

Recent evidences (Balota et al., 2008; Thomas et al., 2012) suggest that the cognitive system can retrospectively (i.e., after target presentation) increase its reliance on prime information when target-word recognition is made more difficult by experimental manipulations such as visual degradation. In fact, response time (RT) distributional analyses have shown that for clearly visible target-words the priming effect has the same size in all the portions of the RT distribution. In contrast, for degraded target-words, priming effects increase across the RT distribution, coherently with the idea of an increased reliance on prime information for degraded targets, which would be particularly beneficial for the most difficult responses (i.e., the slowest ones). The first study (with English-speaking participants), investigated the idea of retrospective prime reliance in the context of an important empirical conundrum within the word recognition literature, produced by the joint effects of stimulus visual quality (SQ), semantic priming and word frequency. The manipulation of these variables, in fact, has traditionally produced constraining results for models of priming (e.g., McNamara, 2005), as well as for visual word recognition models (e.g., Reynolds & Besner, 2004). In Experiment 1, all the three variables have been manipulated within a single speeded pronunciation task, where words and nonwords were randomly appearing as targets. The results indicated that the joint effect of SQ and word frequency on RTs were dependent upon prime relatedness. More specifically, additive effects of SQ and frequency were observed after related primes, while an overadditive interaction was observed after unrelated primes. Distributional analyses showed that this three-way interaction was mediated by slowest RTs and it was hypothesized that the pattern of effects reflects reliance on prime information. To test this hypothesis, in Experiment 2 related primes were eliminated from the list, to produce a context in which there was no reason to rely on prime information. Interactive effects of SQ and frequency found following unrelated primes in Experiment 1 reverted, in Experiment 2, to additive effects for the same unrelated prime conditions. Note that, in English, additive effects of SQ and frequency are found in standard speeded pronunciation tasks (i.e., with no primes), provided that words and nonwords are randomly intermixed in the target set (as was the case in Experiment 2). In a second study, the same experiments as in the first one were tested within a different priming paradigm, namely in zero-lag repetition priming (e.g., Ferguson et al., 2009) and within a different language (Italian). Although distributional analyses provided preliminary evidences that retrospective prime reliance is operative even in this context (Experiment 3), cross-linguistic differences were nonetheless observed. More specifically, in English SQ and frequency produce additive effects in a speeded pronunciation task, provided that nonword targets are intermixed with real words (O’Malley & Besner, 2008) and provided that primes (if present) are all unrelated (Experiment 2). This finding does not seem to be replicated in Italian, where the two variables still produced, in Experiment 4, an overadditive interaction despite the presence of nonwords in the target-set and despite the fact that only unrelated primes were presented (exactly as in Experiment 2). It was hypothesized the discrepancy might stem from the fact that, while in English the system needs to place a functional threshold at an earlier processing level in order to overcome the detrimental effect of visual degradation before lexical representations get activated (thus avoiding lexicalization errors), in a transparent language this might not be the case. It was thus argued that in Italian it is sufficient to increase the reliance on sublexical output, without qualitatively altering the activation-dynamics of the system. The third study explored the possibility that retrospective prime reliance entails episodic retrieval. In a first experiment, English-speaking participants first performed a lexical decision task where SQ and semantic priming were manipulated. After completing the lexical decision and a brief distracter-task, they also performed a recognition memory task on primes presented during the lexical decision. Results showed a trend towards better recognition of those primes that preceded degraded targets, as opposed to clearly visible ones. The result is coherent with the hypothesis that, for those primes that preceded degraded targets, episodic retrieval takes place even in lexical decision, thereby facilitating the recognition of these items in a subsequent memory task. In a second experiment (Italian participants), the effect of SQ in the memory task was not replicated, probably due to specific features of the materials used in the experiment. On the other hand, a strong lexicality effect was found in the memory performance: primes that preceded real words were recognized much better compared to those that preceded nonwords in the previous experimental phase. These results suggest that the interplay between primes and targets, and the cognitive operations required to process them in lexical decision may reflect into the memory traces left by these stimuli. In conclusion, retrospective prime reliance proved to be a useful theoretical tool to understand the joint effect of semantic priming, SQ, and frequency, thereby proposing a new perspective on this issue. Moreover, preliminary evidences suggest that a retrospective component might be involved even in a zero-lag repetition priming paradigm and that the mechanism beside retrospective reliance might entail the episodic retrieval of the prime’s representation. Most importantly, the results highlight the flexibility and the sensitivity of the reading system to the context (i.e., experimental task, characteristics of the stimuli).