Semantic and repetition priming effects for Deese/Roediger—McDermott (DRM) critical items and associates produced by DRM and unrelated study lists

Semantic and episodic processes differently predict false memories in the DRM task

There is a fervent debate about the processes underpinning false memories formation. Seminal theories have suggested that semantic memory would be involved in false memories production, while episodic memory would counter their formation. Yet, direct evidence corroborating such view is still lacking. Here, we tested this possibility by asking participants to perform the Deese-Roediger-McDermott (DRM) task, a typical false memory paradigm, in which they had to study lists of words and subsequently to recognize and distinguish them from new words (i.e., the false memory items). The same participants were also required to perform a semantic task and an episodic-source memory task. Our results showed that a higher number of false memories in the DRM task occurred for those participants with better semantic memory abilities, while a lower number of false memories occurred for participants with better episodic abilities. These findings support a key role of semantic processes in false memory formation and, more generally, help clarify the specific contribution of different memory systems to false recognitions.

Item-specific encoding reduces false recognition of homograph and implicit mediated critical lures

We evaluated the effects of item-specific and relational encoding instructions on false recognition for critical lures that originated from homograph and mediated study lists. Homograph lists contained list items that were taken from two meanings of the same critical lure (e.g., autumn, trip, harvest, stumble; for fall) which disrupted thematic/gist consistency of the list. Mediated lists contained unrelated list items (e.g., slippery, spicy, vent, sleigh) that were indirectly related to a critical lure (e.g., cold), through a set of non-presented mediators (e.g., wet, hot, air, snow), and had no thematic/gist consistency. In two experiments, item-specific and relational encoding improved correct recognition relative to a read-only control task, but only item-specific encoding reduced false recognition of critical lures. Signal-detection analyses indicated that the item-specific reduction increased test-based monitoring. The item-specific reduction for homograph and mediated critical lures is consistent with the activation-monitoring framework given gist-based processes are reduced or eliminated on these list types.

Stroop interference is a composite phenomenon: Evidence from distinct developmental trajectories of its components

Only one previous developmental study of Stroop task performance (Schiller, 1966) has controlled for differences in processing speed that exist both within and between age groups. Therefore, the question of whether the early developmental change in the magnitude of Stroop interference actually persists after controlling for processing speed needs further investigation; work that is further motivated by the possibility that any remaining differences would be caused by process(es) other than processing speed. Analysis of data from two experiments revealed that, even after controlling for processing speed using z-transformed reaction times, early developmental change persists such that the magnitude of overall Stroop interference is larger in 3rd- and 5th graders as compared to 1st graders. This pattern indicates that the magnitude of overall Stroop interference peaks after 2 or 3 years of reading practice (Schadler & Thissen, 1981). Furthermore, this peak is shown to be due to distinct components of Stroop interference (resulting from specific conflicts) progressively falling into place. Experiment 2 revealed that the change in the magnitude of Stroop interference specifically results from joint contributions of task, semantic and response conflicts in 3rd- and 5th graders as compared to a sole contribution of task conflict in 1st graders. The specific developmental trajectories of different conflicts presented in the present work provide unique evidence for multiple loci of Stroop interference in the processing stream (respectively task, semantic and response conflict) as opposed to a single (i.e. response) locus predicted by historically - favored response competition accounts.

Memory processes underlying long-term semantic priming

Two decades of research in semantic priming has provided substantial evidence for a distinction between short- and long-term semantic priming effects. Early models of cognition suggested a single mechanism to explain priming at short and long lags. Later models refuted this explanation and proposed that different mechanisms are necessary to account for different durations of priming effects. Two alternative explanations of long-term semantic priming effects have been proposed in the extant literature. The first explanation is that long-term semantic priming effects rely upon the incremental strengthening of abstract semantic memory representations. The second explanation is that long-term priming is the result of memory for prior cognitive operations. In two experiments, we used different semantic content - word meaning versus category membership - to investigate the mechanisms accountable for long-term semantic priming. Evidence from the two experiments suggests that long-term semantic priming effects are due to different memory processes for different semantic content. Long-term semantic priming of word meanings was dependent on strengthening abstract semantic memory representations and persistent priming of category membership was dependent on memory for prior cognitive operations.

Can false memory for critical lures occur without conscious awareness of list words?

We examined whether the DRM false memory effect can occur when list words are presented below the perceptual identification threshold. In four experiments, subjects showed robust veridical memory for studied words and false memory for critical lures when masked list words were presented at exposure durations of 43 ms per word. Shortening the exposure duration to 29 ms virtually eliminated veridical recognition of studied words and completely eliminated false recognition of critical lures. Subjective visibility ratings in Experiments 3a and 3b support the assumption that words presented at 29 ms were subliminal for most participants, but were occasionally experienced with partial awareness by participants with higher perceptual awareness. Our results indicate that a false memory effect does not occur in the absence of conscious awareness of list words, but it does occur when word stimuli are presented at an intermediate level of visibility.

Emotionally negative pictures enhance gist memory

In prior work on how true and false memory are influenced by emotion, valence and arousal have often been conflated. Thus, it is difficult to say which specific effects are caused by valence and which are caused by arousal. In the present research, we used a picture-memory paradigm that allowed emotional valence to be manipulated with arousal held constant. Negatively valenced pictures elevated both true and false memory, relative to positive and neutral pictures. Conjoint recognition modeling revealed that negative valence (a) reduced erroneous suppression of true memories and (b) increased the familiarity of the semantic content of both true and false memories. Overall, negative valence impaired the verbatim side of episodic memory but enhanced the gist side, and these effects persisted even after a week-long delay. (PsycINFO Database Record

Semantic priming increases word frequency judgments: Evidence for the role of memory strength in frequency estimation

Previous research has demonstrated a systematic, nonlinear relationship between word frequency judgments and values from word frequency norms. This relationship could reflect a perceptual process similar to that found in the psychophysics literature for a variety of sensory phenomena. Alternatively, it could reflect memory strength differences that are expected for words of varying levels of prior exposure. Two experiments tested the memory strength explanation by semantically priming words prior to frequency judgments. Exposure to related word meanings produced a small but measurable increase in target word frequency ratings. Repetition but not semantic priming had a greater impact on low compared to high frequency words. These findings are consistent with a memory strength view of frequency judgments that assumes a distributed network with lexical and semantic levels of representation.

The persistence of content-specific memory operations: priming effects following a 24-h delay

The duration of long-term semantic priming is typically described in minutes. Woltz and Was (2007) found that priming effects following processing in working memory were relatively long-lasting, reporting there was no decrease in priming effects following 32 intervening Stroop-like trials. These findings were interpreted as an increased availability of long-term memory elements, in part due to memory for prior operations, and as not being solely explicable by spreading-of-activation accounts of priming. The present study was designed to test the persistence of these effects following a 24-h delay. In the present study, priming effects were found to be present following a minimum of a 24-h delay between processing of information in working memory and measures of increased availability of long-term memory elements. The results are discussed, in the context of long-term semantic priming, as being the result of persistent memory for prior cognitive operations.

Fast trial pacing in a lexical decision task reveals a decay of automatic semantic activation

We report an experiment showing that reducing attentional resources by presenting trials with a short, 400 ms intertrial interval (ITI) (a) did not affect semantic priming at a 160 ms prime-to-target stimulus-onset asynchrony (SOA), relative to a 2500 ms ITI, and (b) eliminated the priming that occurred at a 1200 ms SOA when the ITI was 2500 ms. However, the elimination of priming at the 1200 ms SOA occurred only when the relatedness proportion (RP, proportion of related primes and targets) was .25 and not when it was .75. We interpret these results as showing that attentional/strategic priming occurs with an RP as low as .25, but only when sufficient attentional resources are available. Equally important, this is the first direct evidence that automatic semantic activation decays within 1200 ms in the standard semantic-priming/lexical-decision paradigm when attentional resources are not being used to maintain the goal of sustaining prime activation. We further argue that the frequent occurrences of related primes and targets with a high RP serve as reminders to maintain that goal such that cognitive load does not reduce long-SOA priming when the RP is high.