Posterior P1 Research Articles

Inhibitory P300 subprocesses and neural compensation in genetic risk for Alzheimer's disease: The case for temporal-spatial principal component analysis.

The P300 event-related potential (ERP) is widely investigated in cognitive neuroscience, including related to aging, with smaller amplitudes and delayed latency consistently reported in Alzheimer's disease (AD). Given that AD-related neurological changes begin years before symptom onset, ERPs in asymptomatic elders with AD risk may characterize early changes. ERPs are seldom studied in this population. Yet, healthy carriers of apolipoprotein-E (APOE) ε4 have evidenced delayed P300 latencies, while P300 amplitude differences are seldom found. However, despite its frequent study, the specific cognitive processes reflected by P300 remain unclear. We propose that these challenges are due to the relatively long P300 window, which likely encompasses multiple underlying subprocesses that overlap in time. Temporal-spatial principal component analysis (tsPCA) maintains the high temporal resolution of EEG and is better suited to isolate processes that overlap in time. Thus, we interrogated APOE ε4 differences in P300 activity during successful stop-signal inhibitory control in healthy, cognitively intact older adults (25 ε4-, 20 ε4+), using both conventional ERP metrics (i.e., mean and peak amplitude) and P300 tsPCA factors. P300 amplitudes did not differ by ε4 using conventional metrics. tsPCA revealed two P300 factors in each ε4 group: first, a Posterior P300 (attention allocation) factor, and second, a relatively Anterior P300 (performance monitoring, evaluating, and updating) factor. tsPCA uniquely revealed greater activity in ε4+ vs. ε4- in Anterior P300. ε4 groups had comparable task performance, suggesting that greater P300 activity in ε4+ likely reflects neural compensation for ε4-related deficits, thereby enabling the maintenance of good task performance.

Risk avoidance and social anxiety in adolescence: Examination of event-related potentials and theta-dynamics on the Balloon Risk Avoidance Task

Adolescents are at relatively high-risk for developing anxiety, particularly social anxiety. A primary hallmark of social anxiety is the impulse to avoid situations that introduce risk. Here, we examined the neural and behavioral correlates of risk avoidance in adolescents (N=59) 11 to 19 years of age. The Balloon Risk Avoidance Task was used with concurrent electroencephalography to measure event-related potentials (frontal P2; late slow-wave; N2, feedback-related negativity, FRN; posterior P3) and oscillatory dynamics (midfrontal theta, 4–7 Hz) in response to unsuccessful and successful risk avoidance conditions. Social anxiety was measured using the Social Phobia and Anxiety Inventory for Children. Results indicated that, across the whole sample, youth exhibited smaller P3, larger FRN, and larger theta responses to unsuccessful risk avoidance. Youth reporting high (compared to low) levels of social anxiety exhibited larger P2, slow-wave, and FRN responses to unsuccessful, compared to successful, risk avoidance. Further, greater social anxiety was associated with reduced theta responses to successful avoidance. Youth with higher levels of social anxiety showed smaller theta responses to both conditions compared to those with low levels of social anxiety. Taken together, the ERP-component differences and weakened theta power in socially anxious youth following unsuccessful avoidance are informative neural correlates for socially anxious youth during risk avoidance.

Flexible processing of distractor stimuli under stress

Acute stress is assumed to affect executive processing of stimulus information, although extant studies have yielded heterogeneous findings. The temporal flanker task, in which a target stimulus is preceded by a distractor of varying utility, offers a means of investigating various components involved in the adjustment of information processing and conflict control. Both behavioral and EEG data obtained with this task suggest stronger distractor-related response activation in conditions associated with higher predictivity of the distractor for the upcoming target. In two experiments we investigated distractor-related processing and conflict control after inducing acute stress (Trier Social Stress Test). Although the stressed groups did not differ significantly from unstressed control groups concerning behavioral markers of attentional adjustment (i.e., Proportion Congruent Effect), or event-related sensory components in the EEG (i.e., posterior P1 and N1), the lateralized readiness potential demonstrated reduced activation evoked by (predictive) distractor information under stress. Our results suggest flexible adjustment of attention under stress but hint at decreased usage of nominally irrelevant stimulus information for biasing response selection.

Neural correlates of adaptive cognitive control in working memory.

Conflicts in working memory (WM) can occur when retrieval cues activate competing items, which impairs the efficiency of retrieval. It has recently been shown that WM retrieval adapts similarly to these conflicts as predicted by conflict monitoring theory for selective attention tasks. Here, we utilized event-related potentials (ERPs) to investigate whether conflict and adaptive control in WM are reflected by the same neural markers that have previously been described for selective attention tasks. In our task, participants encoded two differently colored memory lists that contained four digits each (i.e., 2 5 7 1 and 4 5 9 1), and had to recognize whether a probe item from a specific list and position was correct or incorrect. Conflict during retrieval emerged when digits at corresponding positions (e.g., 2 and 5 at the first position) were different (incongruent), but not when these digits were the same (congruent). In behavioral data, we found a congruency sequence effect, that is, responses to incongruent probe items were slower, and this effect was reduced following trials with incongruent probe items. In ERPs, this behavioral marker of adaptive control was accompanied by two effects. First, congruency affected the amplitude of an N450, and this conflict effect was reduced after incongruent trials. Second, the posterior P3 amplitude varied with the congruency of the current and the previous trial. Both results resemble those found for the Stroop task and thus highlight the similarity between conflict and adaptive control in WM and selective attention tasks.

Of ugly gains and happy losses: An event-related potential study of interactions of the intrinsic and acquired valence of emotional pictures

During the last decades, event-related potential research on the processing of intrinsic and acquired valence has made great progress, but the two dimensions rarely varied simultaneously. Only that way, however, can we investigate whether the acquisition of extrinsic valence varies with intrinsic valence and whether intrinsic and acquired valence share the same brain mechanisms. Forty-five participants performed associative learning of gains and losses, using pictures varying on intrinsic valence (positive, negative) and outcome (90 % gain, 50 %/50 %, 90 % loss). 64-channel EEG was recorded. During acquisition, one picture from each valence/outcome combination was repeatedly presented, followed by abstract outcome information (+10 ct, −10 ct) at the predefined probability. In the test phase, participants pressed buttons to earn the real gains and avoid the real losses associated with the pictures. Here, effects of outcome and/or its congruence with intrinsic valence were observed for RT, error rate, frontal theta power, posterior P2, P300, and LPP. Moreover, outcome systematically affected post-test valence and arousal ratings. During acquisition, a contingency effect (90 % > 50 %) on amplitude of a frontal negative slow wave accompanied the progress of learning, independently of outcome, valence, and congruence. The relative absence of outcome effects during acquisition suggests “cold” semantic rather than genuinely affective processing of gains and losses. However, with real gains and losses in the test phase, “hot” affective processing took place, and outcome and its congruence with intrinsic valence influenced behavior and neural processing. Finally, the data suggest both shared and distinct brain mechanisms of intrinsic and acquired valence.

P3-like signatures of temporal predictions: a computational EEG study.

Many cognitive processes, ranging from perception to action, depend on the ability to predict the timing of forthcoming events. Yet, how the brain uses predictive models in the temporal domain is still an unsolved question. In previous work, we began to explore the neural correlates of temporal predictions by using a computational approach in which an ideal Bayesian observer learned the temporal probabilities of target onsets in a simple reaction time task. Because the task was specifically designed to disambiguate updating of predictive models and surprise, changes in temporal probabilities were explicitly cued. However, in the real world, we are usually incidentally exposed to changes in the statistics of the environment. Here, we thus aimed to further investigate the electroencephalographic (EEG) correlates of Bayesian belief updating and surprise associated with incidental learning of temporal probabilities. In line with our previous EEG study, results showed distinct P3-like modulations for updating and surprise. While surprise was indexed by an early fronto-central P3-like modulation, updating was associated with a later and more posterior P3 modulation. Moreover, updating was associated with a P2-like potential at centro-parietal electrodes, likely capturing integration processes between prior beliefs and likelihood of the observed event. These findings support previous evidence of trial-by-trial variability of P3 amplitudes as an index of dissociable inferential processes. Coupled with our previous findings, the present study strongly bolsters the view of the P3 as a key brain signature of temporal Bayesian inference. Data and scripts are shared on OSF: osf.io/sdy8j/.

Matching different-structured advertising pictorial metaphors with verbalization forms: incongruity-based evoked response potentials evidence.

Many studies emphasize the need of verbally representing pictorial metaphors, but few have empirically investigated whether and how the particular verbalization form match different types of pictorial metaphors. Using evoked response potentials (ERP), a 3 (pictorial structure: fusion, juxtaposition, literal image) × 2 [verbalization form: A(is) B, A(is like) B] within-group experiment was conducted among 36 participants. ERPs were time-locked to the onset of the verb [/(is/is like)] of the metaphor sentence that follows a pictorial metaphor to detect the verbo-pictorial incongruity in metaphor comprehension. The incongruity-based ERP analysis showed that pictorial metaphors, when verbalized in two forms, all induced frontal N1 effect, regardless of pictorial structures, only with a larger N1 amplitude for literal images in "A(is) B." A central stronger P2 was observed in "A(is like) B" for three structures. Despite a general elicitation of posterior P3 in all conditions, a larger P3 was found for juxtapositions verbalized in "A(is like) B" and for literal images verbalized in "A(is) B." There was no significant difference between two verbalization forms for fusion-structured pictorial metaphors. These findings suggest: (1) verbo-pictorial metaphors could induce incongruity-based attention; (2) higher verbo-pictorial semantic congruity and relatedness, indexed by stronger P2 and P3, confirmed "A(is like) B" to be the more effective verbalization form in representing pictorial metaphors, specifically for juxtaposition-structured pictorial metaphors; (3) for non-metaphor advertising pictures, verbal metaphor showed an interference effect. The study not only reveals the neuro-cognitive mechanism of processing verbo-pictorial metaphors, but also offers neural reference for the design of effective multi-modal metaphor by finding an optimal match between PMs and verbalization forms.

P300 as a correlate of false beliefs and false statements.

This study investigates P300 as a component for false belief and false statement processing with and without a communicative context. The purpose is to understand why P300 has been shown to be commonly involved in false belief and lie processing. Participants were presented with a story in which the protagonist holds a true belief and makes a true statement of it (true belief), holds a false belief and makes a true statement (false belief), or holds a true belief and makes a false statement (false statement) while electroencephalograms were recorded. In Experiment 1, featuring a solitary protagonist, stronger posterior P300 was shown in the false belief condition than the true belief and false statement condition. With the installation of a communicative context by including asecondcharacter listening to the protagonist, Experiment2 showed enhanced frontal P300 in the false statement condition compared to the true belief and false belief condition. A late slow wave was more prominent in the false belief condition than in the other two conditions in Experiment 2. The present results suggest a situation-dependent nature of P300. The signal captures the discrepancy between belief and reality more readily than that between belief and words under a noncommunicative context. It becomes more sensitive to the discrepancy between belief and words than that between belief and reality in a communicative situation with an audience, which makes any false statement practically a lie.

Facemasks selectively impair the recognition of facial expressions that stimulate empathy: An ERP study.

Previous research suggests that masks disrupt expression recognition, but the neurophysiological implications of this phenomenon are poorly understood. In this study, 26 participants underwent EEG/ERP recording during the recognition of six masked/unmasked facial expressions. An emotion/word congruence paradigm was used. Face-specific N170 was significantly larger to masked than unmasked faces. The N400 component was larger for incongruent faces, but differences were more substantial for positive emotions (especially happiness). Anterior P300 (reflecting workload) was larger to masked than unmasked faces, while posterior P300 (reflecting categorization certainty) was larger to unmasked than masked faces, and to angry faces. Face masking was more detrimental to sadness, fear, and disgust than positive emotions, such as happiness. In addition, mask covering did not impair the recognition of angry faces, as the wrinkled forehead and frowning eyebrows remained visible. Overall, facial masking polarized nonverbal communication toward the happiness/anger dimension, while minimizing emotions that stimulate an empathic response.

Reduction in right lateralized N2 error response to stroke order violations in poor Chinese word spellers: A study on event-related potential markers for Chinese reading and spelling

Stroke order knowledge is critical for Chinese reading and spelling acquisition. Previous studies have demonstrated enhancements of the N2 and P3 event-related potential (ERP) components at the Pz electrode to stroke order violations of Chinese characters in younger adults. However, it remained unclear whether similar ERP responses could be found in children. The current study investigated the ERP responses to stroke order violations of Chinese characters in children and examined the associations of the ERP responses with children’s Chinese reading and spelling performance. A total of 26 Grade 2 Hong Kong Chinese children observed stroke-by-stroke displays of Chinese characters and judged whether the Chinese characters were written in the correct order. The ERP results showed larger anterior N2 and posterior P3 at the midline electrodes to the incorrect strokes than to the correct strokes. In addition, a smaller right lateralized temporal N2 response to the incorrect strokes was found in poor spellers as compared with good spellers of Chinese. The effect of the right lateralized temporal N2 response on reading performance was fully mediated through spelling ability. These results demonstrated increases in the anterior N2 and posterior P3 responses to stroke order violation of Chinese characters in second graders and suggest the right lateralized N2 response as a potential neural marker of Chinese literacy development in children.

Exposure to loneliness cues reduces prosocial behavior: Evidence from N400 and P300.

Loneliness is a major risk factor for morbidity and mortality. However, the effect of loneliness on subsequent prosocial behavior is not well known. Understanding the neurobiological mechanisms underlying loneliness is necessary to address this research gap. We investigate the mechanism using a modified public goods game (PGG) wherein participants can choose to act for a collective or selfish interest after being exposed to loneliness cues. Both behavioral (Study 1) and event-related potential (ERP) (Study 2) measures were used to explore this relationship. In Study 1 (N = 131), we found that participants exhibited decreased prosocial actions under the loneliness priming condition as opposed to the control condition. In Study 2 (N = 17), frontal N400 and posterior P300 components were identified under the loneliness priming condition as opposed to the control condition. Increased (decreased) frontal N400 and posterior P300 lead to selfish (prosocial) choices. These results indicate that humans instinctively perceive loneliness as inconsistency with their desired social-relational life, which in turn stimulates coping strategies for self-preservation. This study contributes to our understanding of the neurobiological basis of loneliness associated with prosocial behavior.

Attentional tuning of valent word forms

Using event-related brain potentials (ERPs), we tested the hypothesis of valent word forms (Kissler et al., 2006, Prog Brain Res) stating that the mere visual shapes of emotional words acquire valence through numerous co-occurrences with affective activation over an experienced reader's life. Thereby, associations between neuronal representations of visual word forms and affect are strengthened. If so, selective attention to a specific level of the valence of single visual words should not only pre-activate neuronal representations of that level of valence, but this activation should also spread to the associated word forms. This should improve their processing and/or affective discrimination. In a valence-detection task, N = 53 participants made speeded responses only to words of the current target level of valence (negative, neutral, or positive), which varied across separate blocks. We focused on posterior visual P1 and N170 components, two well-established ERP markers of low-level and structural word form processing, respectively. P1 increased from negative over neutral to positive words; this effect was stronger in target compared to nontarget words. N170 was larger for emotional compared to neutral target words, whereas nontarget words showed a strong reverse pattern. The P1 effect for target words and the N170 effect for nontarget words both were driven by good task performers in terms of fast hit responses. Results support the idea of valent word forms that can be tuned by selective attention to valence, which implies both, facilitated affective discrimination and processing of target words, and inhibition of the processing of nontarget words.

The effects of first-dose methylphenidate on the neural signatures of visual selective attention in children with attention-deficit/hyperactivity disorder

Although methylphenidate (MPH) has been shown to significantly improve selective attention in children with attention-deficit/hyperactivity disorder (ADHD), the neural mechanism of this effect remains unclear. We investigated the effects of first-dose MPH on the neural signatures of visual selective attention in children with ADHD. We measured the impact of first-dose MPH on electrophysiological indexes from eighteen children with ADHD (8.9–15.2 years; 15 boys) while they performed a visual search task. MPH was administered in a double-blind placebo-controlled crossover design. MPH led to decreases in behavioral error rates and reaction times. For the electrophysiological indexes, MPH significantly increased the target-elicited N2pc amplitude and posterior P3 amplitude during the selective attention process. The trial-based correlation analysis revealed that the enhanced N2pc (more negative) and P3 (more positive) promoted the behavioral response speed for children with ADHD. The lower individual P3 amplitude was associated with higher severity of inattention symptoms. The severer inattention symptoms were related to weaker MPH effect on N2pc amplitude. These findings suggest that N2pc and P3 are closely related to the mechanism of MPH in the ADHD treatment.

Can Climate Change Awaken Ecological Consciousness? A Neuroethical Approach to Green Consumption

Climate change is a major threat to humanity and endangers our way of life. If a critical mass of consumers can consider the consequences of the daily consumption choices they make, we could hope for a better future. From a neuroethical viewpoint, we examined how a consumer’s ecological consciousness can be awakened, leading to eco-friendly consumption. This study used the neuroscientific method of event-related potentials (ERP) to explore the neural mechanisms underlying climate change. Both frontal N300 and posterior P300 ERP components occur under climate change conditions which is a neural representation of ecological consciousness. Consumers who exhibited simultaneous frontal N300 and posterior P300 activation were more likely than those who did not to make eco-friendly product choices during the consumption tasks. Using these neurobehavioral findings, marketers can promote eco-friendly consumption based on ecological consciousness.

Neural Research on Depth Perception and Stereoscopic Visual Fatigue in Virtual Reality.

Virtual reality (VR) technology provides highly immersive depth perception experiences; nevertheless, stereoscopic visual fatigue (SVF) has become an important factor currently hindering the development of VR applications. However, there is scant research on the underlying neural mechanism of SVF, especially those induced by VR displays, which need further research. In this paper, a Go/NoGo paradigm based on disparity variations is proposed to induce SVF associated with depth perception, and the underlying neural mechanism of SVF in a VR environment was investigated. The effects of disparity variations as well as SVF on the temporal characteristics of visual evoked potentials (VEPs) were explored. Point-by-point permutation statistical with repeated measures ANOVA results revealed that the amplitudes and latencies of the posterior VEP component P2 were modulated by disparities, and posterior P2 amplitudes were modulated differently by SVF in different depth perception situations. Cortical source localization analysis was performed to explore the original cortex areas related to certain fatigue levels and disparities, and the results showed that posterior P2 generated from the precuneus could represent depth perception in binocular vision, and therefore could be performed to distinguish SVF induced by disparity variations. Our findings could help to extend an understanding of the neural mechanisms underlying depth perception and SVF as well as providing beneficial information for improving the visual experience in VR applications.

Event-Related Potentials during Verbal Recognition of Naturalistic Neutral-to-Emotional Dynamic Facial Expressions

Event-related potentials during facial emotion recognition have been studied for more than twenty years. Nowadays, there has been a growing interest in the use of naturalistic stimuli. This research was aimed, therefore, at studying event-related potentials (ERP) during recognition of dynamic facial neutral-to-emotional expressions, more ecologically valid than static faces. We recorded the ERP of 112 participants who watched 144 dynamic morphs depicting a gradual change from a neutral expression to a basic emotional expression (anger, disgust, fear, happiness, sadness and surprise) and labelled those emotions verbally. We revealed some typical ERP, like N170, P2, EPN and LPP. Participants with lower accuracy exhibited a larger posterior P2. Participants with faster correct responses exhibited a larger amplitude of P2 and LPP. We also conducted a classification analysis that yielded the accuracy of 76% for prediction of participants who recognise emotions quickly on the basis of the amplitude of posterior P2 and LPP. These results extend data from previous research about the electroencephalographic correlates of facial emotion recognition.

Attention to affect 2.0: Multiple effects of emotion and attention on event-related potentials of visual word processing in a valence-detection task.

Here we continue recent work on the specific mental processes engaged in a valence-detection task. Fifty-seven participants responded to one predefined target level of valence (negative, neutral, or positive), and ignored the remaining two levels. This enables more precise fine-tuning of neuronal pathways, compared to valence categorization where attention is divided between different levels of valence. Our group recently used valence detection with emotional words. Posterior P1 and N170 effects in the event-related potential (ERP) supported the idea of valent word forms that can be tuned by selective attention to valence. Here we report findings on three distinct posterior N2 components, P300, N400, and the late positive potential (LPP). Target but not nontarget words showed an arousal effect (emotional > neutral) on left-side early posterior negativity (180-280 ms). In contrast, an arousal effect on a sharp N2 deflection in left-minus-right difference ERPs (230-270 ms), suggesting facilitation of lexical access for emotional words, was independent of target status. This also applied to increased medial parieto-occipital N2 (260-300 ms) specific to negative words, indicating attentional capture. Medial-central N400 was specifically enhanced for negative nontarget words, further supporting attentional capture. The typical LPP arousal effect was observed, being stronger and more left-lateralized in target words. An exploratory finding concerned a broad component-overarching ERP valence effect (250-650 ms). Independent of target status, ERPs were more positive for positive than negative words. Combined with our previous results, data suggest multiple loci of emotion-attention interactions in valence detection.

Description of three new species of Bradyidius (Copepoda: Calanoida), the new aetideids from the deep Pacific Ocean, with notes on the genera Bradyidius and Aetideopsis.

Three new aetideid species, Bradyidius abyssalis sp. nov., Bradyidius parabyssalis sp. nov., and B. kurilokamchaticus sp. nov. are described from female specimens collected near the seafloor in the abyss of the Pacific and Atlantic Oceans. Specimens of Bradyidius parabyssalis sp. nov. were obtained in both the Atlantic and Pacific Oceans (Argentine Basin, area of the Meteor Seamount and the Kurile-Kamchatka Trench). Bradyidius abyssalis sp. nov. was found only in the Atlantic Ocean, (Brazil and Guinea Basins and area of the Meteor Seamount) and Bradyidius kurilokamchaticus sp. nov. was recorded from the Kurile-Kamchatka Trench of the Pacific Ocean. Three new herein described Bradyidius species constitute the first documented records of the genus from the abyss of the World Ocean. In addition, three Bradyidius species from the Weddell Sea, the Atlantic Ocean and the Kurile-Kamchatka Trench, are briefly described without biological names due to their bad condition. Bradyidius parabyssalis sp. nov. and B. abyssalis sp. nov. are distinguished from all known congeners by the presence of 3 setae at the basis of the mandible and morphological details of the prosome posterior corners and P1. They show close resemblance to each other but differ in body size, rostrum structure, P4 coxa armament and length of the setae of the antennule ancestral segment I and the mandible basis. Bradyidius kurilokamchaticus sp. nov. shares with B. curtus Markhaseva, 1993, B. pacificus (Brodsky, 1950) and B. arnoldi Fleminger, 1957 a rostrum with non-divergent or parallel points, but differs from these species in the size, the well developed lateral spine on exopod segment 1, in the number of setae at the antenna exopod segment 1 and some morphological details of the prosome posterior corners. Characters that define the genus Bradyidius Giesbrecht, 1897 from Aetideopsis Sars, 1903, i.e. the shape of lateral spines of P1exopod segments 1 and 2; the endopod of P2 segmentation and the setation of the antennule ancestral segments XII, XV and XVII are discussed.

Atypical Developmental Trajectories of Early Perception Among School-Age Children With Attention Deficit Hyperactivity Disorder During a Visual Search Task.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by cognitive deficits associated with attention. Prior studies have revealed the potential impact of ADHD on basic perception and cognitive ability in patients with ADHD. In this study, bilateral posterior P1 and N1 were measured in 122 Chinese children aged 7-12 years (64 with ADHD) to investigate the developmental characteristics of early perception during visual processing in school-age children with ADHD. For children with ADHD, a larger P1 activity with an atypical developmental pattern was evoked and observed for the visual search performance. These findings offer new insights into the mechanisms of cognitive developmental deficits and intervention techniques in children with ADHD.

Priming of grasp affordance in an ambiguous object: evidence from ERPs, source localization, and motion tracking

Object affordance refers to possibilities to interact with the objects in our environment, such as grasping. Previous research shows that objects that afford an action activate the motor system and attract attention, for example they elicit an enhanced frontal negativity and posterior P1 in the event-related potential. An effect on posterior N1 is discussed. However, previous findings might have resulted from physical differences between affording and non-affording stimuli, rather than affordance per se. Here we replicated the frontal negativity and posterior P1 effects and further explored the posterior N1 in affordance processing under constant visual input. An ambiguous target was primed either with an affording (pencils) or non-affording (trees) context. Although physically always identical, the target elicited an enhanced frontal negativity and posterior P1 in the pencil prime condition. Posterior N1 was reduced and grip aperture in a grasping task was smaller in the affording context. Source localization revealed stronger activation in occipital and parietal regions for targets in pencil versus tree prime trials. Thus, we successfully show that an ambiguous object primed with an affording context is processed differently than when primed with a non-affording context. This could be related to the ambiguous object acquiring a potential for action through priming.