The mechanism underlying backward priming in a lexical decision task: Spreading activation versus semantic matching

Koriat (1981) demonstrated that an association from the target to a preceding prime, in the absence of an association from the prime to the target, facilitates lexical decision and referred to this effect as "backward priming". Backward priming is of relevance, because it can provide information about the mechanism underlying semantic priming effects. Following Neely (1991), we distinguish three mechanisms of priming: spreading activation, expectancy, and semantic matching/integration. The goal was to determine which of these mechanisms causes backward priming, by assessing effects of backward priming on a language-relevant ERP component, the N400, and reaction time (RT). Based on previous work, we propose that the N400 priming effect reflects expectancy and semantic matching/integration, but in contrast with RT does not reflect spreading activation. Experiment 1 shows a backward priming effect that is qualitatively similar for the N400 and RT in a lexical decision task. This effect was not modulated by an ISI manipulation. Experiment 2 clarifies that the N400 backward priming effect reflects genuine changes in N400 amplitude and cannot be ascribed to other factors. We will argue that these backward priming effects cannot be due to expectancy but are best accounted for in terms of semantic matching/integration

Examining skilled reading processes

Skilled reading often occurs with little effort. However, when basic reading processes are analyzed in detail, the illusion of simplicity is removed. The present research focuses on the proficiency with which a skilled reader can successfully access lexical (i.e., whole-word) and sublexical (i.e., sub-word) levels of orthographic and phonological knowledge. In particular, I will address questions pertaining to: (1) the nature of the connections between sub-processes of basic visual word recognition, (2) the degree to which context affects whole-word versus sub-word processing, and (3) whether there are neuroanatomical correlates that correspond to the sub-processes of basic visual word recognition. The findings presented in this set of experiments support:(1) facilitation-dominant connections from orthography to phonology, (2) context related whole-word and sub-word processing, and (3) lexical and sublexical neuroanatomical correlates of basic reading processes. The findings are discussed with respect to the issue of whether there is a single processing route from orthography to phonology or if there are two processing routes from orthography to phonology

Nonword Item Generation: Predicting Item Difficulty in Nonword Repetition

abstract: The current study employs item difficulty modeling procedures to evaluate the feasibility of potential generative item features for nonword repetition. Specifically, the extent to which the manipulated item features affect the theoretical mechanisms that underlie nonword repetition accuracy was estimated. Generative item features were based on the phonological loop component of Baddelely's model of working memory which addresses phonological short-term memory (Baddeley, 2000, 2003; Baddeley & Hitch, 1974). Using researcher developed software, nonwords were generated to adhere to the phonological constraints of Spanish. Thirty-six nonwords were chosen based on the set item features identified by the proposed cognitive processing model. Using a planned missing data design, two-hundred fifteen Spanish-English bilingual children were administered 24 of the 36 generated nonwords. Multiple regression and explanatory item response modeling techniques (e.g., linear logistic test model, LLTM; Fischer, 1973) were used to estimate the impact of item features on item difficulty. The final LLTM included three item radicals and two item incidentals. Results indicated that the LLTM predicted item difficulties were highly correlated with the Rasch item difficulties (r = .89) and accounted for a substantial amount of the variance in item difficulty (R2 = .79). The findings are discussed in terms of validity evidence in support of using the phonological loop component of Baddeley's model (2000) as a cognitive processing model for nonword repetition items and the feasibility of using the proposed radical structure as an item blueprint for the future generation of nonword repetition items.Dissertation/ThesisM.A. Educational Psychology 201

The Effects of Semantic Priming on Lexical Processing

The present experiments were designed to investigate the locus of the semantic priming effect, a phenomenon that has received much research attention. Semantically related primes (e.g., cat) might activate the lexical representations of their targets (e.g., DOG) through automatic spreading activation at short stimulus onset asynchronies (SOAs) between the prime and target, or through generation of words expected to follow the prime at long SOAs. Alternately, semantically related primes might be used strategically to aid responding after target identification. The effects of masked orthographic primes (e.g., judpe-JUDGE), in contrast, are assumed to be strictly lexical and automatic. Lexical processing of targets is facilitated by orthographically similar masked nonword primes and is inhibited by orthographically similar masked word primes (Davis & Lupker, 2006). Using the lexical decision task (LDT), I found additivity between the facilitative effects of visible semantic primes at long and short SOAs and the facilitative effects of masked orthographically similar nonword primes and repetition primes. The masked nonword and repetition primes also produced a shift in the latency distribution of target responses, which is consistent with a head-start produced by pre-activating the target lexical representations. Semantic primes affected the skew of the distribution and had a greater effect on trials with longer latencies, consistent with the idea of those primes being used after target identification. Additionally, visible semantic primes at long and short SOAs did not make masked word primes more effective lexical inhibitors of their targets. Taken together, these findings suggest that the impact of a semantic prime is not to increase the lexical activation of its related target. Rather the locus of the semantic priming effect in an LDT appears to be a post-lexical process, consistent with the idea that the effect is due to the discovery of the existence of a relationship between the prime and target which biases participants to make a “word” response

Rare Lexical Speech Automatisms in a Case of Progressive Nonfluent Aphasia

The production of aphasic lexical speech automatisms (yes and right) produced by C.S., a man with progressive speech impairment and primary progressive nonfluent aphasia, were analysed across a range of takes varying in complexity. More automatisms were produced during single word and nonword reading and repetition and picture description than during connected reading and counting, suggesting that internally generated (picture description) and externally triggered (single word and nonword reading and repetition) were equally affected. In addition, a complex speech task (connected reading) produced then fewest automatisms than easier ones (single words). However, tasks where there were increased opportunities for disinhibition produced more automatisms. Results do not suggest that the intrinsic or extrinsic motor speech systems are separately damaged, but do suggest that increased opportunities for disinhibition may produce more automatisms

False memories and lexical decision: even twelve primes do not cause long-term semantic priming

Semantic priming effects are usually obtained only if the prime is presented shortly before the target stimulus. Recent evidence obtained with the so-called false memory paradigm suggests, however, that in both explicit and implicit memory tasks semantic relations between words can result in long-lasting effects when multiple 'primes' are presented. The aim of the present study was to investigate whether these effects would generalize to lexical decision. In four experiments we showed that even as many as twelve primes do not cause long-term semantic priming. In all experiments, however, a repetition priming effect was obtained. The present results are consistent with a number of other results showing that semantic information plays a minimal role in long-term priming in visual word recognition

List Composition Effects for Masked Semantic Primes: Evidence Inconsistent with Activation Accounts

Priming is the benefit that an event receives when its processing has been preceded by the processing of a related or identical event. Context effects on priming are evident when priming changes as a function of some feature of experimental trials. The most commonly explored context effect is that of relatedness proportion (RP), where it has often been shown that the magnitude of priming (semantic or repetition) is directly related to the proportion of related trials: Increasing the related trials results in greater priming. Although previously thought to depend on strategic processing, recent evidence of context effects from designs using masked primes and short stimulus onset asynchronies (SOAs; less than 250 ms) refutes this strategy view because it should not be possible to enact strategies in such brief intervals. In addition, such findings provide evidence against the dominant view that masked priming with short SOAs results from automatic spreading activation because automatic spreading activation should not be influenced by contextual factors. The current set of experiments was designed to provide converging evidence for the notion that episodic accounts may best account for priming by exploring whether differences in another context variable—list composition—would alter semantic priming in a lexical decision task (LDT) for masked, short SOA (67 ms) primes. In 3 experiments, list composition was manipulated by presenting experimental trials that contained either 3 prime types (nominally related, semantically related, or unrelated) or 2 prime types (semantically related or unrelated) in either a between-subjects design (Experiments 1 and 2) or a within-subject design (Experiment 3). List composition effects were found: Response times (RTs) to semantically related primes were associated with a response cost in the 3-Prime-Type condition but were associated with a response benefit (facilitation) in the 2-Prime-Type condition. Episodic accounts can best account for these results, whereby to best facilitate target identification, the cognitive system is biased to detect primes containing features that are most transfer appropriate with respect to targets

The neural and behavioral correlates of target checking in prospective memory

Prospective memory represents the realization of a delayed intention at the appropriate time or in the appropriate environmental context. Strategic monitoring of the environment is one process believed to be important for successful prospective remembering. Guynn (2003) posited that strategic monitoring is comprised of retrieval mode and target checking. Ample evidence has supported the existence of retrieval mode but less is known about the nature of target checking. Using event related potentials (ERPs), this dissertation examined the neural correlates of target checking in a lexical decision task. Experiment 1 was designed to elucidate the physiological correlates of target checking. The physiological data revealed two ERP components that were associated with target checking: the posterior negativity (300-400ms) and the late positive component (600-1000ms). Both components were present during word and nonword trials, but there were differences in how participants engaged the neural processes associated with the posterior negativity and late positive component for the stimulus types. In Experiment 2, the late positive component was hypothesized to be associated with retrieval processes and this hypothesis was examined by varying the number of prospective memory cues. In Experiment 3, the posterior negativity was hypothesized to reflect neural processes associated with the underlying representation of a stimulus so the wordiness of the nonword stimuli was varied to create stimuli that could activate a lexical but not semantic representation. Based on the findings of the three experiments reported herein, target checking appears to involve an early process involving the representation of a stimulus and a late process involving retrieval of representations from memory