Lag-length effect on repetition priming of famous and unfamiliar faces: evidence from N250r and N400

Differentiation of the Contribution of Familiarity and Recollection to the Old/New Effects in Associative Recognition: Insight from Semantic Relation

Previous research has revealed two different old/new effects, the early mid-frontal old/new effect (a.k.a., FN400) and the late parietal old/new effect (a.k.a., LPC), which relate to familiarity and recollection processes, respectively. Although associative recognition is thought to be more based on recollection, recent studies have confirmed that familiarity can make a great contribution when the items of a pair are unitized. However, it remains unclear whether the old/new effects are sensitive to the nature of different semantic relations. The current ERP (event-related potentials) study aimed to address this, where picture pairs of thematic, taxonomic, and unrelated relations served as stimuli and participants were required to discriminate the pair type: intact, rearranged, “old + new”, or new. We confirmed both FN400 and LPC. Our findings, by comparing the occurrence and the amplitudes of these two components, implicate that the neural activity of associative recognition is sensitive to the semantic relation of stimuli and depends more on stimulus properties, that the familiarity of a single item can impact the neural activities in discriminating associative pairs, and that the interval length between encoding and test modulates the familiarity of unrelated pairs. In addition, the dissociation between FN400 and LPC reinforces the dual-process models.

Is color source retrieval sensitive to emotion? Electrophysiological evidence from old/new effects

It has been proved that item memory and source memory are two dissociable processes, as reflected by differential influence at behavioral and electrophysiological levels, the latter being evidenced by the ERP old/new effects. Specially for source memory, the retrieval of color source may be unique from recollecting other types of contextual information, which can be seen from the late posterior negativity (LPN). However, the mediation of emotional valence on the old/new effects for verbal stimuli encoded in colors remains unknown. Adopting words of three emotional valences (i.e., positive, neutral, and negative), with their displayed colors serving as sources, the current experiment aimed to explore the sensitivity of old/new effects to emotion for both item memory and source memory. Results demonstrated that: the FN400 that reflects familiarity was recorded and it was sensitive to emotional valence across both memory tasks; the mediation of emotional valence was absent in recollection-reflected LPC, neither for item memory nor for source memory; an association between LPN and color source retrieval was confirmed, with reliable amplitudes for neutral words but not for emotional words. These data were discussed in terms of the dual-process model and other accounts. Future research directions were recommended.

External (Versus Internal) Facial Features Contribute Most to Repetition Priming in Facial Recognition: ERP Evidence

Previous event-related potential (ERP) research demonstrated four successive ERP components in the repetition priming of human face recognition: P100, N170, N250r, and N400. While these components correspond, respectively, to the four stages proposed by the interactive activation and competition (IAC) model, there has been no emphasis in past research on how internal and external facial features affect repetition priming and the sensitivity of these ERP components to item interval. This study was designed to address these issues. We used faces of celebrities as targets, including completely familiar faces, familiar internal feature faces, and familiar external feature faces. We displayed a target face either immediately following its prime (immediate repetition) or after a delay with interference from a presentation of two other faces (delayed repetition). ERP differences at P100 and N170 were nearly statistically non-significant; familiar faces and familiar external feature faces were associated with reliable ERP signals of N250r and N400 in the immediate repetition condition. For delayed repetition, however, N250r and N400 signals were only preserved for the familiar external feature faces. The differences of these ERP components suggest that, compared with internal facial features, external features of a previously presented face contribute more to brain-based facial repetition priming, particularly during the last two stages of the IAC model.

Sensitivity of Reality Monitoring to Fluency: Evidence from Behavioral Performance and Event-Related Potential (ERP) Old/New Effects

Background

Item memory and source memory are differently processed with both behavioral and event-related potential (ERP) evidence. Reality monitoring, a specific type of source memory, which refers to the ability to differentiate external sources from internal sources, has been drawing much attention. Among factors that have an impact on reality monitoring, fluency has not been well-studied. Therefore, the current study aimed to investigate whether fluency could affect reality monitoring, through observations on both behavioral performance and electrophysiological patterns.

Material/Methods

Adopting ERP techniques, participants were required either to watch the presentation of a name/picture pair, or to imagine a picture for each displayed name, once (low fluency) or twice (high fluency). Later they completed a reality monitoring task of identifying names as perceived, imagined, or novel items. Behavioral performance was measured, and ERP waveforms were recorded.

Results

Behaviorally, high fluency items were faster and more accurately attributed to the sources than low fluency items. ERP waveforms revealed that late positive component (LPC) occurred for all 4 types of items, while imagined items of low fluency did not record a robust FN400 or late frontal old/new effect.

Conclusions

As results revealed, the factor of fluency does influence reality monitoring in terms of accuracy and responding speed. Meanwhile, for imagined items of low fluency, the absence of FN400 and frontal old/new effect also suggests the sensitivity of reality monitoring to fluency, because these representatives of familiarity-based processing and post-retrieval monitoring are inevitably involved in the process of differentiating internal source from external source.

Influence of lag length on repetition priming in emotional stimuli: ERP evidence

BACKGROUND

Previous studies have demonstrated both behavioral and neural evidence for the potential mediations of lag length and pre-existing memory representation on repetition priming. However, such mediations on emotional stimuli have not been described.

METHODS

The current experiment intended to disentangle lag length from pre-existing memory representation. A lexical decision task was performed, in which different emotional characters (either normal or transposed) were re-presented either immediately or delayed.

RESULTS

In immediate repetition, one early and two late (ie, N400 and late positive complex) repetition-related event-related potential (ERP) effects were elicited, but these were not sensitive to pre-existing memory representation. The delayed repetition case merely observed the N400.

CONCLUSION

These results suggest that the repetition-related priming effect is neutrally sensitive to lag length. Emotional information potentially exerts early and later influences in the processing underlying stimuli memory.