Separating the role of perceptual and conceptual fluency on masked word priming using event-related potentials.

Masked word repetition increases "old" responses on an episodic recognition test (Jacoby & Whitehouse, 1989). This effect is commonly attributed to perceptual fluency; that is, unconscious perception of the prime speeds reading of the target and this fluency leads to elevated familiarity. Two experiments directly tested the claim that perceptual fluency is responsible for word priming effects. Experiment 1 held prime-target meaning constant and altered the physical characteristics of match primes (e.g., "RIGHT" primes "RIGHT") by including both lowercase (e.g, "right") and mixed case primes (e.g., "rIgHt"). If word priming effects are due to perceptual fluency, then lowering the perceptual overlap between the prime and target should decrease or eliminate word priming effects. Instead, all three conditions showed robust priming effects in the behavioral and ERP (i.e., N400) measures. Experiment 2 equated the prime-target perceptual features and lowered the conceptual overlap by using orthographically similar nonwords as primes (e.g., "JIGHT" primes "RIGHT"). Removing prime-target conceptual overlap eliminated behavioral evidence of priming and N400 ERP differences correlated with priming. The evidence suggests that word priming effects on episodic recognition memory are more likely a product of conceptual fluency than perceptual fluency.

Event-Related Potential (ERP) evidence for fluency and disfluency effects on recognition memory.

Masked priming is used in recognition memory studies to alter fluency and create familiarity. Primes are flashed briefly before target words that are considered for a recognition judgment. Matching primes are hypothesized to produce greater familiarity by increasing the perceptual fluency of the target word. Experiment 1 tested this claim by contrasting match primes (i.e., "RIGHT" primes "RIGHT"), semantic primes (e.g., "LEFT" primes "RIGHT"), and orthographically similar (OS) primes (e.g., "SIGHT" primes "RIGHT") while recording event-related potentials (ERPs). Relative to match primes, OS primes elicited fewer "old" responses and more negative ERPs during the interval associated with familiarity (300-500 ms). This result was replicated when control primes consisting of unrelated words (Experiment 2) or symbols (Experiment 3) were inserted into the sequence. The behavioral and ERP evidence suggest that word primes are perceived as a unit and the prime word activation will affect target fluency and recognition judgments. When the prime matches the target, fluency is increased and more familiarity experiences are created. When the primes are words that do not match the target, fluency is decreased (disfluency) and fewer familiarity experiences result. This evidence suggests that the effects of disfluency on recognition should be carefully considered.

Context dissociations of the FN400 and N400 are evidence for recognition based on relative or absolute familiarity.

Fluency, the ease of processing, can increase familiarity and the ability to recognize previously encountered information. Mixing or blocking the pre-experimental familiarity of test probes alters the pattern of recognition Event-Related Potentials (ERPs) for picture stimuli (Bruett & Leynes, 2015). The present study tested this idea further by mixing or blocking pre-experimental familiarity of word stimuli. A test with only pre-experimentally familiar words (Experiment 1) elicited the prototypical mid-frontal FN400 old/new ERP difference, which is a correlate of familiarity. However, tests with a mix of pre-experimentally familiar and unfamiliar words (Experiment 2) elicited posterior N400 old/new differences. Based on the Unexpected Fluency Attribution model (Mecklinger & Bader, 2020), this pattern of results suggests that pre-experimental fluency can influence the use of relative (changes from recent exposure) or absolute (baseline levels accrued from experience) familiarity to make a recognition judgment.

The effect of test query on recognition event-related potentials (ERPs).

The influence of question framing (i.e., [was the item] "old?" or "new?") on recognition memory and event-related potentials (ERPs) was investigated. Words were encoded using a shallow task to create a weak memory trace that was more susceptible to test question framing effects. Participants made yes/no judgments on two, counterbalanced tests. One test focused on old items ("old?"), whereas the other test focused on new items ("new?"). The behavioral evidence suggested that the weak memory traces led to more familiarity-based recognition judgments with a concentrated effect on decision criterion. There were some small ERP changes on the FN400 or LPC consistent with the criterion changes, but the test query did not directly alter these ERP components. Instead, the test query altered a late old/new ERP difference similar to the "right frontal old/new effect" reported in source monitoring ERP studies. When the query was "new?", old items elicited more positive ERPs, whereas there was no old/new difference when the query was "old?". The results suggest that the query framing induces memory biases that occur late in the stream of processing. More generally, the results indicate that decision criterion must be accounted for when interpreting physiological correlates of recognition memory.

Expectations alter recognition and event-related potentials (ERPs).

Two studies investigated the effect of recognition expectancies (Experiment 1) and decision criterion (Experiment 2) on event-related potentials (ERPs). Participants in both experiments studied meaningless pictures of abstract art and then completed three recognition memory tests with equal proportions of old and new items. To manipulate expectancies (Experiment 1), participants were told to expect equal numbers of old and new items (standard expectancy), more old items (old expectancy), or more new items (new expectancy). The meaningless stimuli did not elicit recognition ERPs under standard testing expectancies, whereas the same stimuli elicited old/new ERP effects in the FN400 and LPC time windows when participants expected more old items. Decision criterion manipulations (Experiment 2) produced different ERP patterns indicating that expectancies alter the decision criterion and produce unique effects on recognition. Collectively, these findings support theory that describes familiarity as an experience that arises from assessing the processing fluency relative to a set of expectations (Whittlesea & Williams, 2001a, 2001b).

Event-related potential (ERP) evidence for fluency-based recognition memory.

Two experiments investigated the influence of perceptual fluency on recognition memory. Words were studied using a shallow encoding task to decrease the contribution of recollection on recognition. Fluency was manipulated by blurring half of the test probes. Clarity varied randomly across trials in one experiment and was grouped into two blocks (clear and blurry) in the other experiment. Clarity did not influence recognition judgments or the ERP correlate of familiarity (FN400) when clarity was blocked across trials, but fluent probes (old and clear) elicited a more negative ERP than less fluent probes 280-400 ms at parietal electrode sites. Random variations in clarity produced the opposite pattern of results because recognition judgments and FN400 amplitudes varied, whereas the early ERPs did not differ. The results are interpreted as evidence that blocking clarity across trials led to recognition that was based on repetition fluency differences (i.e., old more fluent than new), which was associated with an early (280-400 ms) ERP at parietal electrodes in the absence of FN400 differences. Randomly varying clarity across trials created a situation where repetition fluency and perceptual fluency (i.e., probe clarity) interacted and led recognition to be based on familiarity/conceptual implicit memory that was associated with FN400 amplitudes in the absence of early ERP differences. The behavioral and ERP differences suggest that perceptual fluency, by itself, is capable of supporting recognition in some contexts and that, in other contexts, fluency can combine with other memory trace information to support recognition.

The effect of specific test queries on source-monitoring event-related potentials.

Source-monitoring decision processes were manipulated during retrieval while event-related potentials (ERPs) were recorded. Words were either seen or heard at study, and memory for modality was measured on two separate yes-no source tests. Decision processes were varied across the two tests by asking participants to respond to leading questions. One leading question asked if the items were seen at study, whereas the second question asked if the items were heard at study (cf., Marsh & Hicks, 1998). Behavioral responses indicated that leading questions altered the way in which memory was evaluated to determine the source of information. Varying the decision processes affected frontal--but not parietal ERPs--indicating that frontal ERPs reflect processing that is used to evaluate activated information. Furthermore, left and right frontal ERP activity was affected by the combination of test query and type of source supporting the hypothesis that both the right and left frontal lobes contribute to memory retrieval processes. The pattern of frontal ERP effects supports the hypothesis that activation in right frontal areas reflect basic decision processes that are used to determine source and that the left frontal lobes are recruited when more systematic processing is required by the test context (cf., Nolde, Johnson, & Raye, 1998b).