Relatedness Proportion Research Articles

Attentional control and the relatedness proportion effect in semantic priming.

In 2 experiments, participants completed both an attentional control battery (OSPAN, antisaccade, and Stroop tasks) and a modified semantic priming task. The priming task measured relatedness proportion (RP) effects within subjects, with the color of the prime indicating the probability that the to-be-named target would be related. In Experiment 2, participants were cued before each trial with the probability of a related target. Stimulus onset asynchronies traditionally thought to tap automatic processing (267 ms) versus controlled processing (1,240 ms) were used. Across experiments, principal component analysis on the battery revealed a general attentional control component. Moreover, the RP effect increased linearly with attentional control in both experiments. It is concluded that RP effects produced in this paradigm depend purely upon the effortful process of expectancy generation, which renders them sensitive to individual differences in attentional control.

Dissociative effects of stimulus quality on semantic and morphological contexts in visual word recognition.

Semantic and morphological contexts were manipulated jointly with stimulus quality under conditions where there were few related prime-target pairs (i.e., low relatedness proportion) in a lexical decision experiment. Additive effects of semantic context and stimulus quality on RT were observed, replicating previous work. In contrast, morphological context interacted with stimulus quality. This dissociation is discussed in the context of Besner and colleagues' evolving multistage framework. The essence of the account is that 1) stimulus quality affects feature and letter levels, but not later levels, 2) feedback from semantics to the lexical level is inoperative under low relatedness proportion conditions (hence stimulus quality and semantic context yield additive effects), whereas 3) feedback from the lexical level to the letter level is intact, hence stimulus quality and morphological context produce an interaction by virtue of them affecting a common stage of processing.

Relatedness proportion effects on masked associative priming: An ERP study

Abstract The effect of relatedness proportion (the percentage of related words in a list) on associative priming was investigated in two masked priming experiments. In Experiment 1, subjects were randomly assigned to either a high (80%) or low (20%) relatedness proportion condition and performed a lexical decision task. Semantically related and unrelated primes were briefly flashed (50 ms) before the targets and were preceded by a mask that prevented their overt identification. In Experiment 2, subjects were tested in both relatedness proportion conditions in a categorization task; the N400, an electrophysiological index of lexical and semantic priming, was measured in trials that did not require a button press. Behavioral and electrophysiological priming effects were observed in both high and low relatedness proportion conditions. The observed priming effects were not modulated by relatedness proportion. The results are discussed in terms of current theories of associative priming.

Implications of measures of reliability for theories of priming: Activity in semantic memory is inherently noisy and uncoordinated

In experiments on semantic priming, participants vary substantially in the absolute magnitude of priming they produce. Are these individual differences systematic or do they arise from random processes, and does the answer carry theoretical implications? To find out, we examined split‐half and test–retest reliability of semantic priming in a series of two‐session experiments that crossed relatedness proportion (RP, at .25, .50, and .75) with stimulus–onset asynchrony (SOA, at 200, 350, and 800 ms). Low reliability would indicate little coherence of activity within semantic memory, so that the degree to which any given association influences performance is uncorrelated from one association and time of testing to the next. High reliability would indicate that each person tends to harness his or her semantic knowledge consistently, applying semantic relations among words in much the same way from one word to the next and one time of testing to the next to help task performance, resulting in systematic individual differences. What we observed was low reliability—often zero. When conditions highlighted “automatic activation” (low RP, short SOA), priming was completely uncorrelated from item to item and session to session. Both split‐half and test–retest reliability increased to significant levels under conditions that raised the probability that an activated or retrieved episode of prime experience would help with target recognition, and the probability of intentionally generating the target from the prime. Thus, task‐relevant" utility imposes a modicum of order on semantic associations that are otherwise noisy and uncoordinated. Harnessing semantic memory is like herding cats—without considerable constraint, associations tend to come and go their own ways in independent fashion.

Beyond spreading activation: An influence of relatedness proportion on masked semantic priming

Semantic priming in the lexical decision task has been shown to increase when the proportion of related-prime trials is increased. This finding typically is taken as evidence for a conscious, strategic use of primes. Three experiments are reported in which masked semantic primes displayed for only 45 msec were tested in high- versus low-relatedness proportion conditions. Relatedness proportion was increased either by using a high proportion of semantically related primes or a large set of repetition-primed filler trials. Semantic priming was consistently enhanced relative to a low-relatedness proportion condition. These relatedness proportion effects were not due to conscious, strategic use of primes: Exclusion of prime-aware subjects did not attenuate the effects, and better performance in a prime classification task was not associated with larger semantic priming effects. These results are interpreted within a retrospective account of semantic priming in which recruitment of a prime event is modulated by prime validity.

Priming of strong semantic relations in the left and right visual fields: a time-course investigation

Prior time-course investigations of cerebral asymmetries in word processing have sometimes reported hemisphere differences in the onset and duration of semantic priming. In the current study, very strongly related word pairs (categorical associates such as arm– leg) were employed in a low relatedness proportion lexical decision priming paradigm. A range of prime–target stimulus onset asynchronies (SOAs: 150–800 ms) was included. Only very weak evidence was obtained for a LVF priming lag at the briefest SOA, while priming was bilateral at moderately long SOAs. We consider these data in the context of previous time-course studies and suggest that, when highly semantically similar word pairs are used, a right hemisphere priming lag is, at best, a very small effect.

Does the proportion of associatively related pairs modulate the associative priming effect at very brief stimulus-onset asynchronies?

A number of experiments have shown that the magnitude of the associative priming effect increases substantially when there is a high proportion of associatively related pairs in the list when the stimulus-onset asynchrony (SOA) between prime and target is long (more than 400 ms). In the present series of experiments we manipulated the proportion of associatively related pairs when the SOA was very brief (less than 200 ms). If processing of a target word is facilitated automatically by the prior presentation of a related prime, the occurrence of priming should be unaffected by the proportion of related pairs in the list. Experiment 1 showed a robust relatedness proportion effect obtained in a double lexical decision task. Experiments 2–4 used the masked priming technique at several very short SOAs (66, 116, and 166 ms) in lexical decision and naming. The results showed a reliable associative priming effect in the two tasks, which did not differ as a function of the proportion of related pairs. Finally, Experiment 5 used unmasked primes at an 83-ms SOA in which the primes remained in view after the target presentation. As in Experiments 2–4, the associative effect was not modulated by the proportion of associatively related pairs. The implications of these results are discussed.

Semantic Priming in Parkinsons Disease: Evidence for Delayed Spreading Activation

Nineteen persons with Parkinsons disease (PD) and 19 matched control participants completed a battery of online lexical decision tasks designed to isolate the automatic and attentional aspects of semantic activation within the semantic priming paradigm. Results highlighted key processing abnormalities in PD. Specifically, persons with PD exhibited a delayed time course of semantic activation. In addition, results suggest that experimental participants were unable to implicitly process prime information and, therefore, failed to engage strategic processing mechanisms in response to manipulations of the relatedness proportion. Results are discussed in terms of the Gain/Decay hypothesis (Milberg, McGlinchey-Berroth, Duncan, Higgins, 1999) and the dopaminergic modulation of signal to noise ratios in semantic networks.

Semantic Priming in Alzheimer's Dementia: Evidence for Dissociation of Automatic and Attentional Processes

The nature of the semantic memory deficit in dementia of the Alzheimer's type (DAT) was investigated in a semantic priming task which was designed to assess both automatic and attention-induced priming effects. Ten DAT patients and 10 age-matched control subjects completed a word naming semantic priming task in which both relatedness proportion (RP) and stimulus-onset asynchrony (SOA) were varied. A clear dissociation between automatic and attentional priming effects in both groups was demonstrated; however, the DAT subjects' pattern of priming deviated significantly from that of the normal controls. The DAT patients failed to produce any priming under conditions which encouraged automatic semantic processing and produced facilitation only when the RP was high. In addition, the DAT group produced hyperpriming, with significantly larger facilitation effects than the control group. These results suggest an impairment of automatic spreading activation in DAT and have implications for theories of semantic memory impairment in DAT as well as models of normal priming.

With great expectations, can two "wrongs" prime a "right"?

The proportion of related prime-target pairs (relatedness proportion, RP) and prime-target stimulus onset asynchrony (SOA) was varied to determine the involvement of strategic priming mechanisms in the reduction in semantic priming that occurs when a target follows an unmasked prime that itself receives immediate repetition priming from a masked prime. At 300-ms and 1,200-ms SOAs, (a) strategic semantic priming was operating, in that priming from a nonrepeated prime increased as RP increased from .25 to .75, and (b) for both RPs, prime repetition reduced semantic priming. At a 167-ms SOA, (a) priming from a nonrepeated prime was unaffected by RP, suggesting that strategic priming was not operating, and (b) for both RPs, prime repetition did not reduce semantic priming. Because prime repetition did not reduce priming at the 167-ms SOA (when only spreading activation should have been mediating semantic priming), the reduction in semantic priming produced by prime repetition is not evidence against spreading activation automaticity. Possible mechanisms through which prime repetition reduces semantic priming are discussed.

An Event-Related Brain Potential Analysis of Visual Word Priming Effects

Two experiments are reported that provide evidence on task-induced effects during visual lexical processing in a prime–target semantic priming paradigm. The research focuses on target expectancy effects by manipulating the proportion of semantically related and unrelated word pairs. In Experiment 1, a lexical decision task was used and reaction times (RTs) and event-related brain potentials (ERPs) were obtained. In Experiment 2, subjects silently read the stimuli, without any additional task demands, and ERPs were recorded. The RT and ERP results of Experiment 1 demonstrate that an expectancy mechanism contributed to the priming effect when a high proportion of related word pairs was presented. The ERP results of Experiment 2 show that in the absence of extraneous task requirements, an expectancy mechanism is not active. However, a standard ERP semantic priming effect was obtained in Experiment 2. The combined results show that priming effects due to relatedness proportion are induced by task demands and are not a standard aspect of online lexical processing.

Effects of relatedness proportion on semantic priming : An event-related potential analysis

Effects of relatedness proportion on semantic priming : An event-related potential analysis

Differences in semantic category priming in the left and right cerebral hemispheres under automatic and controlled processing conditions

The contribution of each cerebral hemisphere to the generation of semantic category meanings at automatic and strategic levels of processing was investigated in a priming experiment where prime and target words were independently projected to the left or right visual fields (LVF or RVF). Non-associated category exemplars were employed as related pairs in a lexical decision task and presented in two experimental conditions. The first condition was designed to elicit automatic processing, so related pairs comprised 20% of the positive set, stimulus pairs were temporally separated by a stimulus onset asynchrony (SOA) of 250 ms, and there was no allusion to the presence of related pairs in the instructions to subjects. The second condition, designed to invoke controlled processing, incorporated a relatedness proportion of 50%, stimulus pairs separated by an SOA of 750 ms, and instructions which informed subjects of the presence and use of category exemplar pairs in the stimulus set. In the first condition, a prime directed to either visual field facilitated responses to categorically related targets subsequently projected to the RVF, while in the second condition a prime directed to either visual field facilitated responses to related targets projected to the LVF. The facilitation effects obtained in both conditions appeared to reflect automatic processes, while strategic processes were invoked in the left, but not the right hemisphere in the second condition. The results suggest that both hemispheres have automatic access to semantic category meanings, although the timecourse of activation of semantic category meanings is slower in the right hemisphere than in the left.

Examining the role of word identification in synonymy judgment

This paper examines the role of word identification in semantic judgment tasks. We argue that word-identification processes can substantially alter the functional properties of semantic judgment tasks. We investigate this empirically by examining the effects of semantic relatedness and relatedness proportion on synonymy judgments of non-synonym pairs. The results demonstrate that semantic relatedness slows synonymy judgments for non-synonym pairs when the relatedness proportion is low, but speeds them when the relatedness proportion is high. The former effect is a replication of traditional findings, while the latter effect reverses these findings. We explain these results by hypothesizing that increasing the relatedness proportion increases the beneficial effects of semantic relatedness in word identification, and this produces the reversal of traditional findings. We close by emphasizing that models of semantic judgment tasks can become more comprehensive by focusing on word identification.

Phonological priming reflects lexical competition

A phonological relationship between a prime and a target produces facilitation when one or two initial phonemes are shared (low-similarity facilitation) but produces interference when more phonemes are shared (high-similarity interference; Slowiaczek & Hamburger, 1992). Although low-similarity facilitation appears to be a strategic effect (Goldinger, Luce, Pisoni, & Marcario, 1992), this result cannot generalize to high-similarity interference because the two effects are dissociated (Slowiaczek & Hamburger, 1992). In the present study, strategic processing in high-similarity interference was investigated. The phonological relatedness proportion (PRP) and the prime-target interstimulus interval (ISI) were varied in a shadowing experiment. Low-similarity facilitation was found only with a high PRP and long ISI, but high-similarity interference was found regardless of PRP and ISI. These results suggest that strategies influence low-similarity facilitation, but high-similarity interference reflects automatic processing.

Dissociated Identity and Semantic Priming in Broca's Aphasia: How Controlled Processing Produces Inhibitory Semantic Priming

Broca's aphasics performed a lexical decision task in a semantic priming experiment in which the proportion of related words was manipulated with a sufficiently long stimulus onset asynchrony for expectancy-based, strategic processing to operate. The control subjects showed the typical increase in semantic facilitation as relatedness proportion increased. However, the aphasic subjects demonstrated the opposite effect such thatinhibitorysemantic priming occurred as relatedness proportion increased even though, in a second experiment, these same aphasics showed an increase infacilitatoryidentity priming as relatedness proportion increased. This striking dissociation of identity and semantic priming for the aphasics was interpreted as supporting the “center-surround” theory (Carr & Dagenbach, 1990), which accounts for the same dissociation found in the normal population under challenging word-recognition conditions.

Capacity demands of automatic processes in semantic priming

In three experiments, we examined the effects of prime-target stimulus onset asynchrony (SOA) and the proportion of related primes and targets (relatedness proportion, or RP) on semantic priming when the prime was either named or was searched for a specific letter. In Experiment 1, with an RP of .50, priming occurred at SOAs of 240 and 840 msec when the prime was named, but no priming was found at either SOA when the prime was searched for a letter. In Experiment 2 the RP was either .20 or .80, and the SOA was set at 1,700 msec; priming again was found in both conditions when the prime was named, but only in the RP .80 condition when a letter search task was performed on the prime. In Experiment 3, both the proportion of related trials and SOA were varied; as in the previous experiments, no priming effects were found with the letter search task for either SOA in the RP .20 condition, but the priming effect was reinstated in the RP .80 condition. These results are discussed with respect to how limited capacity resources are allocated and how they influence semantic priming effects.

Semantic priming in the pronunciation task: The role of prospective prime-generated expectancies

In the relatedness proportion effect, semantic priming increases with an increase in the probability that a word prime will be followed by a semantically related word target. This effect has frequently been obtained in the lexical decision task but not in a pronunciation task. In the present experiment, relatedness proportion was manipulated in two pronunciation tasks, one with and one without nonword targets, using category names as primes. In both tasks, a relatedness proportion effect occurred for high-dominance category exemplars but not for low-dominance category exemplars. These results converge with recent lexical decision results in suggesting that semantic priming in pronunciation is affected by a prospective prime-generated expectancy that is modulated by the relatedness proportion.

Semantic priming in the lexical decision task: Roles of prospective prime-generated expectancies and retrospective semantic matching.

In semantic priming paradigms for lexical decisions, the probability that a word target is semantically related to its prime (the relatedness proportion) has been confounded with the probability that a target is a nonword, given that it is unrelated to its prime (the nonword ratio). This study unconfounded these two probabilities in a lexical decision task with category names as primes and with high- and low-dominance exemplars as targets. Semantic priming for high-dominance exemplars was modulated by the relatedness proportion and, to a lesser degree, by the nonword ratio. However, the nonword ratio exerted a stronger influence than did the relatedness proportion on semantic priming for low-dominance exemplars and on the nonword facilitation effect (i.e., the superiority in performance for nonword targets that follow a category name rather than a neutral XXX prime). These results suggest that semantic priming for lexical decisions is affected by both a prospective prime-generated expectancy, modulated by the relatedness proportion, and a retrospective target/prime semantic matching process, modulated by the nonword ratio.