Unexpected Stimuli Research Articles

On the physiology of interruption after unexpectedness

We tested whether surprise elicits similar physiological changes as those associated with orienting and freezing after threat, as surprise also involves a state of interruption and attention for effective action. Moreover, because surprise is primarily driven by the unexpectedness of an event, initial physiological responses were predicted to be similar for positive, neutral, and negative surprises. Results of repetition-change studies (4 + 1 in Supplemental Materials) showed that surprise lowers heart rate (Experiments 1-4) and increases blood pressure (Experiment 4). No effects on body movement (Experiment 2) or finger temperature (Experiment 4) were found. When unexpected stimuli were presented more often (making them less surprising) heart rate returned to baseline, while blood pressure remained high (Experiment 4). These effects were not influenced by stimulus valence. However, second-to-second analyses within the first (surprising) block showed a tendency for a stronger increase in systolic blood pressure after negative vs. positive surprise.

Horses show individual level lateralisation when inspecting an unfamiliar and unexpected stimulus.

Animals must attend to a diverse array of stimuli in their environments. The emotional valence and salience of a stimulus can affect how this information is processed in the brain. Many species preferentially attend to negatively valent stimuli using the sensory organs on the left side of their body and hence the right hemisphere of their brain. Here, we investigated the lateralisation of visual attention to the rapid appearance of a stimulus (an inflated balloon) designed to induce an avoidance reaction and a negatively valent emotional state in 77 Italian saddle horses. Horses’ eyes are laterally positioned on the head, and each eye projects primarily to the contralateral hemisphere, allowing eye use to be a proxy for preferential processing in one hemisphere of the brain. We predicted that horses would inspect the novel and unexpected stimulus with their left eye and hence right hemisphere. We found that horses primarily inspected the balloon with one eye, and most horses had a preferred eye to do so, however, we did not find a population level tendency for this to be the left or the right eye. The strength of this preference tended to decrease over time, with the horses using their non-preferred eye to inspect the balloon increasingly as the trial progressed. Our results confirm a lateralised eye use tendency when viewing negatively emotionally valent stimuli in horses, in agreement with previous findings. However, there was not any alignment of lateralisation at the group level in our sample, suggesting that the expression of lateralisation in horses depends on the sample population and testing context.

Expectation-driven novelty effects in episodic memory

Novel and unexpected stimuli are often prioritised in memory, given their inherent salience. Nevertheless, not all forms of novelty show such an enhancement effect. Here, we discuss the role expectation plays in modulating the way novelty affects memory processes, circuits, and subsequent performance. We first review independent effects of expectation on memory, and then consider how different types of novelty are characterised by expectation. We argue that different types of novelty defined by expectation implicate differential neurotransmission in memory formation brain regions and may also result in the creation of different types of memory. Contextual novelty, which is unexpected by definition, is often associated with better recollection, supported by dopaminergic-hippocampal interactions. On the other hand, expected stimulus novelty is supported by engagement of medial temporal cortices, as well as the hippocampus, through cholinergic modulation. Furthermore, when expected stimulus novelty results in enhanced memory, it is predominantly driven by familiarity. The literature reviewed here highlights the complexity of novelty-sensitive memory systems, the distinction between types of novelty, and how they are differentially affected by expectancy.

Threat-relevant stimuli cannot be better detected by preschoolers in an inattentional blindness task.

Detecting the unexpected threat-relevant stimuli plays a vital role in preschoolers' daily life safety, but a few studies have investigated how preschoolers process this kind of stimuli. We applied a classical inattentional blindness task (designed by Mack and Rock Inattentional blindness. MIT Press, 1998) to explore whether threat-relevant stimuli could be better detected in an inattentional condition and whether the age and the fluid intelligence could predict the incidence of the detection. With the involvement of two hundred and thirty-nine preschoolers (aged from 4 to 6years), we found that it was not more likely for preschoolers to detect the threat-relevant stimuli (Knife and Snake) compared with the non-threat-relevant stimuli (Spoon and Snail). The age difference of detection only occurred in the divided attentional condition, but not in the inattentional condition. Moreover, the group of 5-year-old preschoolers with higher fluid intelligence scores was more likely to detect the unexpected stimuli, but the prediction was not powerful. These findings demonstrate that the threat-superiority effect on IB does not occur on preschoolers and the individual difference of preschoolers' IB is unstable. This study enriches the cognition of young children's attentional bias to threat-relevant stimuli, and has certain significance to understand the essence of children's attentional process.

Acetaminophen does not affect Cardiac and Brain Responses to Social Rejection but seems to attenuate Behavioral Adaptation in a Social Judgement Task

The present study examined the effect of Acetaminophen on the painful experience of social rejection by examining brain, cardiac and behavioral measures reflecting different aspects of social feedback processing. Healthy students (N=72), after ingesting either Acetaminophen or a placebo, performed a social judgement paradigm (SJP), in which they could be expectedly or unexpectedly rejected or accepted. During the task, cardiac and brain responses to different types of feedback were measured, as well as expectancies relating to the given feedback. Enhanced cardiac deceleration was found after unexpected social rejection as compared to all other conditions. Larger mean P3 amplitude was found after expected positive and negative feedback stimuli as compared to unexpected stimuli. While cardiac deceleration and P3 were not affected by Acetaminophen, behavioral responses were. While in the control group the percentage of acceptance predictions decreased over the experiment (learning from negative feedback), the Acetaminophen group did not adjust their positive prediction bias over time. The unexpected effect of Acetaminophen on prediction behavior suggests that Acetaminophen might indeed play a role in social pain perception. The normally observed social pain-based learning effect seems to disappear when participants ingest Acetaminophen, which can be interpreted as a reduced pain perception after Acetaminophen.

Positive and negative prediction error signals to violated expectations of face and place stimuli distinctively activate FFA and PPA

Surprising scenarios can have different behavioural and neuronal consequences depending on the violation of the expectation. On the one hand, previous research has shown that the omission of a visual stimulus results in a robust cortical response representing that missing stimulus, a so-called negative prediction error. On the other hand, a large amount of studies revealed positive prediction error signals, entailing an increased neural response that can be attributed to the experience of a surprising, unexpected stimulus. However, there has been no evidence, so far, regarding how and when these prediction error signals co-occur. Here, we argue that the omission of an expected stimulus can and often does coincide with the appearance of an unexpected one. Therefore, we investigated whether positive and negative prediction error signals evoked by unpredicted cross-category stimulus transitions would temporally coincide during a speeded forced-choice fMRI paradigm. Foremost, our findings provide evidence of a behavioural effect regarding the facilitation of responses linked to expected stimuli. In addition, we obtained evidence for negative prediction error signals as seen in differential activation of FFA and PPA during unexpected place and face trials, respectively. Lastly, a psychophysiological interaction analysis revealed evidence for positive prediction error signals represented by context-dependent functional coupling between the right IFG and FFA or PPA, respectively, implicating a network that updates the internal representation after the appearance of an unexpected stimulus through involvement of this frontal area. The current results are consistent with a predictive coding account of cognition and underline the importance of considering the potential dual nature of expectation violations. Furthermore, our results put forward that positive and negative prediction error signalling can be directly linked to regions associated with the processing of different stimulus categories.

Persistence, Reward Dependence, and Sensitivity to Reward Are Associated With Unexpected Salience Response in Girls but Not in Adult Women: Implications for Psychiatric Vulnerabilities

BackgroundAdolescence is a critical period for the development of not only personality but also psychopathology. These processes may be specific to sex, and brain reward circuits may have a role. Here, we studied how reward processing and temperament associations differ across adolescent and adult females. MethodsA total of 29 adolescent girls and 41 adult women completed temperament assessments and performed a classical taste conditioning paradigm during brain imaging. Data were analyzed for the dopamine-related prediction error response. In addition, unexpected stimulus receipt or omission and expected receipt response were also analyzed. Heat maps identified cortical-subcortical brain response associations. ResultsAdolescents showed stronger prediction error and unexpected receipt and omission responses (partial η2 = 0.063 to 0.166; p = .001 to .043) in insula, orbitofrontal cortex (OFC), and striatum than adults. Expected stimulus receipt response was similar between groups. In adolescents versus adults, persistence was more strongly positively related to prediction error (OFC, insula, striatum; Fisher’s z = 1.704 to 3.008; p = .001 to .044) and unexpected stimulus receipt (OFC, insula; Fisher’s z = 1.843 to 2.051; p = .014 to .033) and negatively with omission (OFC, insula, striatum; Fisher’s z = −1.905 to −3.069; p = .001 to .028). Reward sensitivity and reward dependence correlated more positively with unexpected stimulus receipt and more negatively with stimulus omission response in adolescents. Adolescents showed significant correlations between the striatum and FC for unexpected stimulus receipt and omission that correlated with persistence but were absent in adults. ConclusionsAssociations between temperamental traits and brain reward response may provide neurotypical markers that contribute to developing adaptive or maladaptive behavior patterns when transitioning from adolescence to adulthood.

PRIMING EFFECTS FOR THE UNEXPECTED STIMULUS IN INATTENTIONAL BLINDNESS

Studies on inattentional blindness demonstrate that a stimulus that unexpectedly appears in the visual environment may be undetected when attention is engaged in a task. The stimulus can still be processed and remembered at the perceptual and semantic level. The question of whether this is still the case when there are items to be ignored in the visual environment remains. In the present study investigating this question, participants attended to furniture pictures while they ignored other pictures. In the inattention trial, an unexpected word appeared in the middle of the circular display. Participants blind to the word were compared to ones who were not exposed to the word. In Experiment 1, participants were more likely to complete a word fragment with this word than the ones who were not exposed to the word. In Experiment 2, participants were more likely to choose the picture of this word than the ones who were not exposed to the word. These studies show that the undetected unexpected stimulus is processed at the perceptual and semantic level and produces priming effects on a subsequent task. Findings were discussed with regards to the possible memory correlates of undetected visual information and levels of consciousness. Keywords: inattentional blindness, priming, consciousness, perceptual processing, semantic processing

Relationships between expertise and distinctiveness: Abnormal medical images lead to enhanced memory performance only in experts

Memories are encoded in a manner that depends on our knowledge and expectations ("schemas"). Consistent with this, expertise tends to improve memory: Experts have elaborated schemas in their domains of expertise, allowing them to efficiently represent information in this domain (e.g., chess experts have enhanced memory for realistic chess layouts). On the other hand, in most situations, people tend to remember abnormal or surprising items best-those that are also rare or out-of-the-ordinary occurrences (e.g., surprising-but not random-chess board configurations). This occurs, in part, because such images are distinctive relative to other images. In the current work, we ask how these factors interact in a particularly interesting case-the domain of radiology, where experts actively search for abnormalities. Abnormality in mammograms is typically focal but can be perceived in the global "gist" of the image. We ask whether, relative to novices, expert radiologists show improved memory for mammograms. We also test for any additional advantage for abnormal mammograms that can be thought of as unexpected or rare stimuli in screening. We find that experts have enhanced memory for focally abnormal images relative to normal images. However, radiologists showed no memory benefit for images of the breast that were not focally abnormal, but were only abnormal in their gist. Our results speak to the role of schemas and abnormality in expertise; the necessity for spatially localized abnormalities versus abnormalities in the gist in enhancing memory; and the nature of memory and decision-making in radiologists.

Auditory mismatch negativity in bipolar disorder: a focused review.

The auditory mismatch negativity, a component of the event-related potential elicited by an unexpected stimulus in a sequence of acoustic stimuli, provides an objective measure of the accuracy of the echoic information processing of the human brain in vivo. Auditory mismatch negativity is also a useful probe of cortical glutamatergic N-methyl-d-aspartate receptor activity and disturbance. Notably, auditory mismatch negativity is consistently impaired in schizophrenia. Because of the wide spectrum extending from bipolar affective illness and schizoaffective psychosis to typical schizophrenia, we examined the literature on auditory mismatch negativity in bipolar disorder with the aim to find any neurophysiological dysfunction concerning pre-attentive information processing shared by these clinical conditions. This focused review includes 26 original articles published in peer-reviewed journals and indexed in the National Institutes of Health National Library of Medicine (PubMed) search system. Overall, evidence is consistent with the finding that auditory mismatch negativity is impaired in bipolar disorder with psychotic features, even though to a lesser extent than in schizophrenia. It must be acknowledged that, in a few twin and family studies, mismatch negativity abnormalities were not specifically associated with bipolar disorder. In conclusion, auditory mismatch negativity research supports the involvement of the N-methyl-d-aspartate system in the pathophysiology of bipolar disorder, as previously assessed for schizophrenia, thus creating an intriguing trait d'union between these two mental illnesses and stimulating the development of novel therapeutic agents. With additional replication and validation, auditory mismatch negativity may be further considered as a correlate of a common psychopathology of schizophrenia and bipolar spectrum illnesses.

Rescue of two trafficking-defective variants of the neuronal glycine transporter GlyT2 associated to hyperekplexia

Hyperekplexia is a rare sensorimotor syndrome characterized by pathological startle reflex in response to unexpected trivial stimuli for which there is no specific treatment. Neonates suffer from hypertonia and are at high risk of sudden death due to apnea episodes. Mutations in the human SLC6A5 gene encoding the neuronal glycine transporter GlyT2 may disrupt the inhibitory glycinergic neurotransmission and cause a presynaptic form of the disease. The phenotype of missense mutations giving rise to protein misfolding but maintaining residual activity could be rescued by facilitating folding or intracellular trafficking. In this report, we characterized the trafficking properties of two mutants associated with hyperekplexia (A277T and Y707C, rat numbering). Transporter molecules were partially retained in the endoplasmic reticulum showing increased interaction with the endoplasmic reticulum chaperone calnexin. One transporter variant had export difficulties and increased ubiquitination levels, suggestive of enhanced endoplasmic reticulum-associated degradation. However, the two mutant transporters were amenable to correction by calnexin overexpression. Within the search for compounds capable of rescuing mutant phenotypes, we found that the arachidonic acid derivative N-arachidonoyl glycine can rescue the trafficking defects of the two variants in heterologous cells and rat brain cortical neurons. N-arachidonoyl glycine improves the endoplasmic reticulum output by reducing the interaction transporter/calnexin, increasing membrane expression and improving transport activity in a comparable way as the well-established chemical chaperone 4-phenyl-butyrate. This work identifies N-arachidonoyl glycine as a promising compound with potential for hyperekplexia therapy.

Propagation and update of auditory perceptual priors through alpha and theta rhythms.

To maintain a continuous and coherent percept over time, the brain makes use of past sensory information to anticipate forthcoming stimuli. We recently showed that auditory experience of the immediate past is propagated through ear‐specific reverberations, manifested as rhythmic fluctuations of decision bias at alpha frequencies. Here, we apply the same time‐resolved behavioural method to investigate how perceptual performance changes over time under conditions of stimulus expectation and to examine the effect of unexpected events on behaviour. As in our previous study, participants were required to discriminate the ear‐of‐origin of a brief monaural pure tone embedded in uncorrelated dichotic white noise. We manipulated stimulus expectation by increasing the target probability in one ear to 80%. Consistent with our earlier findings, performance did not remain constant across trials, but varied rhythmically with delay from noise onset. Specifically, decision bias showed a similar oscillation at ~9 Hz, which depended on ear congruency between successive targets. This suggests rhythmic communication of auditory perceptual history occurs early and is not readily influenced by top‐down expectations. In addition, we report a novel observation specific to infrequent, unexpected stimuli that gave rise to oscillations in accuracy at ~7.6 Hz one trial after the target occurred in the non‐anticipated ear. This new behavioural oscillation may reflect a mechanism for updating the sensory representation once a prediction error has been detected.

Listener\u2019s personality traits predict changes in pupil size during auditory language comprehension

Research suggests that listeners’ comprehension of spoken language is concurrently affected by linguistic and non-linguistic factors, including individual difference factors. However, there is no systematic research on whether general personality traits affect language processing. We correlated 88 native English-speaking participants’ Big-5 traits with their pupillary responses to spoken sentences that included grammatical errors, "He frequently have burgers for dinner"; semantic anomalies, "Dogs sometimes chase teas"; and statements incongruent with gender stereotyped expectations, such as "I sometimes buy my bras at Hudson's Bay", spoken by a male speaker. Generalized additive mixed models showed that the listener's Openness, Extraversion, Agreeableness, and Neuroticism traits modulated resource allocation to the three different types of unexpected stimuli. No personality trait affected changes in pupil size across the board: less open participants showed greater pupil dilation when processing sentences with grammatical errors; and more introverted listeners showed greater pupil dilation in response to both semantic anomalies and socio-cultural clashes. Our study is the first one demonstrating that personality traits systematically modulate listeners’ online language processing. Our results suggest that individuals with different personality profiles exhibit different patterns of the allocation of cognitive resources during real-time language comprehension.

Encoding-linked pupil response is modulated by expected and unexpected novelty: Implications for memory formation and neurotransmission

Whether a novel stimulus is expected or unexpected may have implications for the kind of ensuing encoding and the type of subsequent memory. Pupil response was used in the present study to explore the way expected and unexpected stimuli are encoded and whether encoding-linked pupil response is modulated by expectation. Participants first established a contingency relationship between a series of symbols and the type of stimulus (man-made or natural) that followed each one. At encoding, some of the target stimuli violated the previously established relationship (i.e., unexpected), while the majority conformed to this relationship (i.e., expected). Expectation at encoding had opposite effects on familiarity and recollection, the two types of memory that support recognition, and modulated differently the way pupil response predicted subsequent memory. Encoding of unexpected novel stimuli was associated with increased pupil dilation as a predictor of subsequent memory type and strength. In contrast, encoding of expected novel stimuli was associated with decreased pupil response (constriction), which was predictive of subsequent memory type and strength. The findings support the close link between pupil response and memory formation, but critically indicate that this is modulated by the type of novelty as defined by expectation. These novel findings have important implications for the encoding mechanisms involved when different types of novelty are detected and is proposed to indicate the operation of different neurotransmitters during memory formation.

Do Auditory Mismatch Responses Differ Between Acoustic Features?

Mismatch negativity (MMN) is the electroencephalographic (EEG) waveform obtained by subtracting event-related potential (ERP) responses evoked by unexpected deviant stimuli from responses evoked by expected standard stimuli. While the MMN is thought to reflect an unexpected change in an ongoing, predictable stimulus, it is unknown whether MMN responses evoked by changes in different stimulus features have different magnitudes, latencies, and topographies. The present study aimed to investigate whether MMN responses differ depending on whether sudden stimulus change occur in pitch, duration, location or vowel identity, respectively. To calculate ERPs to standard and deviant stimuli, EEG signals were recorded in normal-hearing participants (N = 20; 13 males, 7 females) who listened to roving oddball sequences of artificial syllables. In the roving paradigm, any given stimulus is repeated several times to form a standard, and then suddenly replaced with a deviant stimulus which differs from the standard. Here, deviants differed from preceding standards along one of four features (pitch, duration, vowel or interaural level difference). The feature levels were individually chosen to match behavioral discrimination performance. We identified neural activity evoked by unexpected violations along all four acoustic dimensions. Evoked responses to deviant stimuli increased in amplitude relative to the responses to standard stimuli. A univariate (channel-by-channel) analysis yielded no significant differences between MMN responses following violations of different features. However, in a multivariate analysis (pooling information from multiple EEG channels), acoustic features could be decoded from the topography of mismatch responses, although at later latencies than those typical for MMN. These results support the notion that deviant feature detection may be subserved by a different process than general mismatch detection.

Brief report: Musical improvisation skills can combat labile hypertension

• Our data supports the conclusion that musical improvising has the potential to both blunt emotional distress (i.e. through mindfulness) and impact negative thoughts and emotions in ways that can help labile hypertension. This may additionally help patients better anticipate and react to seen and unforeseen stressors in daily life. Notably, patients who participated in this study not only learned a new technique to address labile hypertension, but indicated they are also more likely to practice mindfulness and exercise techniques to benefit their health. All of these pathways can potentially lessen the impact of labile hypertension and give patients an engaging option to treat this condition that is common in so many patients. Patients with labile hypertension experience transient but substantial increases in blood pressure, usually surrounding episodes of emotional distress and anxiety. Difficulties with or inability to express negative emotions may play a role. We hypothesize that therapy involving musical improvisation may blunt emotional response but may also decrease brain activity associated with negative thoughts and emotions. Unlike relaxation techniques that involve music, musical improvisation includes listening and creating music in a heightened state of awareness, listening and spontaneous interaction with music, and involves decreased activity in brain structures associated with negative thoughts and emotions. Improvisation experiences allow improvisers to predict and to anticipate what might occur in the moment, actively engaging in any unexpected “stress” that may come their way. (Palatini et al., 1998 Jul) To create and to improvise, musicians move past the anxiety of failure of being able to interact with unexpected stimuli, and we postulated that with a similar educational approach, patients may be able to better manage their labile hypertension.

Population codes of prior knowledge learned through environmental regularities

How the brain makes correct inferences about its environment based on noisy and ambiguous observations is one of the fundamental questions in Neuroscience. Prior knowledge about the probability with which certain events occur in the environment plays an important role in this process. Humans are able to incorporate such prior knowledge in an efficient, Bayes optimal, way in many situations, but it remains an open question how the brain acquires and represents this prior knowledge. The long time spans over which prior knowledge is acquired make it a challenging question to investigate experimentally. In order to guide future experiments with clear empirical predictions, we used a neural network model to learn two commonly used tasks in the experimental literature (i.e. orientation classification and orientation estimation) where the prior probability of observing a certain stimulus is manipulated. We show that a population of neurons learns to correctly represent and incorporate prior knowledge, by only receiving feedback about the accuracy of their inference from trial-to-trial and without any probabilistic feedback. We identify different factors that can influence the neural responses to unexpected or expected stimuli, and find a novel mechanism that changes the activation threshold of neurons, depending on the prior probability of the encoded stimulus. In a task where estimating the exact stimulus value is important, more likely stimuli also led to denser tuning curve distributions and narrower tuning curves, allocating computational resources such that information processing is enhanced for more likely stimuli. These results can explain several different experimental findings, clarify why some contradicting observations concerning the neural responses to expected versus unexpected stimuli have been reported and pose some clear and testable predictions about the neural representation of prior knowledge that can guide future experiments.

The effect of emotional valence and age of faces on adults and children's inattentional blindness.

Inattentional blindness (IB) refers to the nature of an individual being unaware of an unexpected stimulus when focusing on an attentional task. Investigation into IB provides an innovative approach for the research of attentional bias that is connected with an individual's immediate attentional capture. This study explored the effect of emotional valence and age of faces on the IB rates of children and adults. We employed a between-subject experimental design with a 2 (age of participants: child, adult) × 2 (age of face: child face, adult face) × 2 (emotional valence: positive, negative) method and used the classic IB task of cross judgment. The participants included 79 adults (54.63 ± 8.192 years old) and 78 children (10.62 ± 2.32 years old). The results showed that: (1) The IB rates of the two groups differed significantly. Children performed better than adults in detecting the faces appearing unexpectedly. (2) The effect of emotional valence only emerged on adult participants' IB. Adults were significantly more likely to detect the positive-emotional faces than the negative-emotional ones. (3) The age of a face was not a significant factor to predict participants' IB. Neither children nor adults showed a preference for the faces of a specific age (e.g., their own age). These findings revealed the distinct characteristics of attentional capture of children and adults when confronting unexpected facial stimuli.

Don't blink: inattentional blindness in radiology report interpretation.

Objectives:Medical errors attributable to inattentional blindness (IAB) may contribute to adverse patient outcomes. IAB has not been studied in the context of reviewing written radiological reports. This cross-sectional, deception-controlled study measures IAB of physicians towards an unexpected stimulus while interpreting written radiological reports.Methods:Physicians and residents from multiple fields were asked to interpret four radiology text reports. Embedded in one was an unexpected stimulus (either an abnormally placed medical exam finding or a non-medical quote from the popular television show Doctor Who). Primary outcomes were differences in detection rates for the two stimuli. Secondary outcomes were differences in detection rates based on level of training and specialty.Results:The unexpected stimulus was detected by 47.8% (n = 43) of participants; the non-medical stimulus was detected more often than the medical stimulus (75.0% vs 21.7%, odds ratio 10.8, 95% confidence interval 4.1–28.7; p < 0.0001). No differences in outcomes were observed between training levels or specialties.Conclusion:Only a minority of physicians successfully detected an unexpected stimulus while interpreting written radiological reports. They were more likely to detect an abnormal non-medical stimulus than a medical stimulus. Findings were independent of the level of training or field of medical practice.Advances in knowledge:This study is the first to show that IAB is indeed present among internal medicine, family medicine, and emergency medicine providers when interpreting written radiology reports.

Pre-stimulus alpha predicts inattentional blindness.

Pre- and post-stimulus oscillatory activity between 8 and 12 hertz, referred to as the alpha-band, correlates with conscious visual awareness of stimuli across a variety of psychophysical tasks. Within an EEG-adapted inattentional blindness task, the current study sought to examine whether this relationship holds for conscious awareness of stimuli under conditions of inattentional blindness. Noticing rates of the task-irrelevant unexpected stimulus were correlated with a significant decrease in alpha power over bilateral parietal-occipital areas during the pre-stimulus interval, and a significant decrease in alpha power over parietal-occipital regions in the right hemisphere during the post-stimulus interval. Findings are taken to imply alpha-band neural activity represents a valid correlate of consciousness that is not confounded by task relevancy or the need for report.