Nonhuman primate studies traditionally use two or three animals. We previously used standard statistics to argue for using either one animal, for an inference about that sample, or five or more animals, for a useful inference about the population. A recently proposed framework argued for testing three animals and accepting the outcome found in the majority as the outcome that is most representative for the population. The proposal tests this framework under various assumptions about the true probability of the representative outcome in the population, that is, its typicality. On this basis, it argues that the framework is valid across a wide range of typicalities. Here, we show (1) that the error rate of the framework depends strongly on the typicality of the representative outcome; (2) that an acceptable error rate requires this typicality to be very high (87% for a single type of outlier), which actually renders empirical testing beyond a single animal obsolete; and (3) that moving from one to three animals decreases error rates mainly for typicality values of 70%-90% and much less for both lower and higher values. Furthermore, we use conjunction analysis to demonstrate that two out of three animals with a given outcome only allow to infer a lower bound to typicality of 9%, which is of limited value. Thus, the use of two or three animals does not allow a useful inference about the population, and if this option is nevertheless chosen, the inferred lower bound of typicality should be reported.

While the unmasked priming paradigm has effectively revealed a biphasic pattern of morphological decomposition-early morpho-orthographic segmentation followed by later morpho-semantic integration-it remains unsettled which ERP components reliably reflect these distinct stages of morphological processes. To address this, we systematically compared ERP responses across three priming conditions-morphological (e.g., swiftly-swift), orthographic (e.g., surgeon-surge), and semantic (e.g., explode-burst)-focusing on the N250, early N400, late N400, and late negativity (LN). The N250 showed no facilitative effects and instead exhibited increased negativities across all conditions, challenging its reliability as a marker of early morpho-orthographic processing under unmasked priming. In contrast, both the early and late N400 subcomponents provided consistent indices of morpho-orthographic segmentation and morpho-semantic integration, respectively. In the early N400, morphological priming elicited earlier and stronger negativity attenuation than orthographic priming, with minimal semantic influence-reflecting semantically blind morpho-orthographic segmentation. In the late N400, negativity attenuation for morphological priming was further amplified and exceeded that of semantic priming, indicating morpho-semantic integration via shared morphemes. Notably, we also observed a unique biphasic orthographic priming pattern with embedded word targets: a relatively short and weak early N400 attenuation followed by an LN peak, reflecting initial facilitation from embedded word identification and subsequent lateral inhibition between orthographically related but semantically unrelated words. These findings establish the early and late N400 as robust ERP signatures of biphasic morphological processing under unmasked priming and elucidate the temporal dynamics of morphological, orthographic, and semantic processes.

Human navigation heavily relies on visual information. Although many previous studies have investigated how navigational information is inferred from visual features of scenes, little is understood about the impact of navigational experience on visual scene representation. In this study, we examined how navigational experience influences both the behavioral and neural responses to a visual scene. During training, participants navigated in the virtual reality (VR) environments, which we manipulated navigational experience while holding the visual properties of scenes constant. Half of the environments allowed free navigation (navigable), while the other half featured an "invisible wall" preventing the participants to continue forward even though the scene was visually navigable (nonnavigable). During testing, participants viewed scene images from the VR environment while completing either a behavioral perceptual identification task (Experiment 1) or an fMRI scan (Experiment 2). Behaviorally, we found that participants judged a scene pair to be significantly more visually different if their prior navigational experience varied, even after accounting for visual similarities between the scene pairs. Neurally, multivoxel pattern of the parahippocampal place area distinguished visual scenes based on prior navigational experience alone. These results suggest that the human visual scene cortex represents information about navigability obtained through prior experience, beyond those computable from the visual properties of the scene. Taken together, these results suggest that scene representation is modulated by prior navigational experience to help us construct a functionally meaningful visual environment.

Cortical activity shows the ability to recover from distractions. We analyzed neural activity from the pFC of monkeys performing working memory tasks with mid-memory delay distractions (a cued gaze shift or an irrelevant visual input). After distraction, there were state-space rotational dynamics that returned spiking to population patterns similar to those predisruption. In fact, rotations were fuller when the task was performed correctly versus when errors were made. We found a correspondence between state-space rotations and traveling waves across the surface of pFC. This suggests a role for emergent dynamics like state-space rotations and traveling waves in recovery from distractions.

Ongoing thoughts play a critical role in modulating cognitive performance, with phenomena such as mind wandering consistently associated with decreased task accuracy and prolonged RTs. However, the neural mechanisms underlying the influence of thought dimensions on cognition and behavior remain unclear. To elucidate this, we used EEG to investigate how two key thought dimensions-deliberate control (deliberate vs. spontaneous thoughts) and task relatedness (on-task vs. off-task thoughts)-modulate RT during a simple RT task. Behavioral results showed that both on-task and more deliberate thoughts were associated with shorter RTs compared to off-task and more spontaneous thoughts. Neurodynamic analyses revealed that on-task and deliberate thoughts were characterized by prestimulus increases in both frequency sliding, reflecting faster phase-based neural speed, and sample entropy, reflecting higher neural uncertainty/flexibility. Both prestimulus frequency sliding and sample entropy were significantly related to the degree of poststimulus intertrial phase coherence, which, in turn, correlated with RT. This sequential relationship suggests that phase-based neural dynamics play a crucial role in mediating the relationship of thought with task-related behavior. Together, these findings suggest that phase-based neural dynamics could play a key modulatory role across the divide of prestimulus and poststimulus activity in shaping the influence of ongoing thoughts (deliberate control and task relatedness) on task execution and its related behavior (RT).

This study investigates intelligence-related differences in the adjustment of brain activity and connectivity to varying cognitive demands, testing for a moderation of an association between intelligence and neural efficiency by task difficulty. In 72 young adults (34 female, 38 male), fMRI brain activity changes during a decision-making task with five levels of difficulty were related to intelligence scores from a nonverbal matrix reasoning test. In frontoparietal, subcortical, and cerebellar regions activated during task processing, we observed smaller increases in brain activity in more intelligent participants-independent of task difficulty. However, in two regions of the default mode network, dorsomedial prefrontal cortex and left angular gyrus, more intelligent participants showed greater decreases in activity with increasing task difficulty. Furthermore, with increasing difficulty, more intelligent participants showed greater increases in functional connectivity of dorsomedial prefrontal cortex and angular gyrus. These findings suggest a more dynamic adjustment of neural processing to varying cognitive demands in more intelligent individuals. Particularly when it comes to more difficult tasks, more intelligent people seem to be better able to down-regulate activity in the brain's default mode network. Due to the relatively small sample size, these findings must be considered preliminary. While their interpretation should therefore be treated with caution, they suggest conceptually new avenues for replication in larger samples. As far as the observed processes reflect the suppression of task-unrelated neural processing and a better focus on the task at hand, they can potentially explain the general performance advantage of more intelligent individuals across various cognitive tasks.

Whenever a perceived event violates expectations compared with an expected event, the cortical response to this event tends to be augmented. The increase in cortical responses signals a mismatch between expectation and observation. Mismatch patterns of neural activity have been repeatedly observed in adults, but their emergence and evolution in infancy are not well understood, since most prediction-inducing paradigms require learning the association or rule underpinning the expectation, thus conflating the violation response with the ability to learn. To address this shortcoming, this article reports a neuroimaging study with 2- to 6-month-olds that measured neural responses to the colocation (expected or matched) or dislocation (deviant or mismatch) of sounds and visual events. The results indicated that even in early infancy, the brain is sensitive to violations of expectation: Stimuli that deviated from expectation elicited stronger neural responses in these infants' sensory cortices than expected stimuli.

Attention restoration theory suggests that natural environments offer greater restorative benefits compared with urban settings. While previous research has used behavioral and questionnaire measures to demonstrate the effects of nature exposure on cognition, mood, and stress, fewer studies have explored physiological measures. This study used EEG and ECG to investigate the behavioral and psychophysiological markers of nature restoration, along with estimating the moderating influence of individual differences in nature relatedness on restorative effects. Forty participants were randomly assigned to view either natural or urban images in a short virtual exposure after completion of a cognitively fatiguing Stroop task. EEG and ECG were continuously recorded throughout a pre/post design measuring heart rate variability, ERPs, EEG frequency band power, cognitive performance (digit span test, flanker go/no-go task), mood (Positive and Negative Affect Schedule), and state mindfulness (Mindful Attention Awareness Scale). Scores on the Nature Relatedness Scale were utilized as a moderator variable. EEG results showed an increase in alpha power during both nature and urban exposures. A neural index of inhibitory control (N2 ERP amplitude) was decreased for the nature group only, possibly reflecting more efficient inhibitory attentional processing. Nature relatedness moderated environmental effects for alpha and beta power, overall RT, and positive affect, whereby effects were enhanced when exposures aligned with nature relatedness level. In conclusion, this study suggests that nature exposure can influence cortical inhibitory mechanisms involved in suppressing distractions. The influence of nature relatedness indicates that nature restoration is not necessarily universal but contingent on individuals' connection to a given environment.

Statistical learning (SL) is a powerful mechanism that supports the ability to extract regularities from environmental input. Yet, its neural underpinnings are not well understood. Previous EEG studies of SL have found that the brain tracks regularities by synchronizing its activity with the presented stimuli-a phenomenon known as neural entrainment. However, EEG lacks the spatial resolution to unveil the specific brain regions where this process takes place. In our study, 18 patients with drug-resistant epilepsy who were implanted with intracranial electrodes for presurgical investigation listened to a continuous speech stream containing embedded trisyllabic words. Neural entrainment was measured at the syllable and word frequencies, with the latter providing an online index of learning. SL was further assessed through both explicit and implicit behavioral measures. Behaviorally, we found evidence of learning at the group level in both tasks. At the neural level, our analyses revealed three temporal tuning profiles: 25% of contacts showed entrainment at the syllable frequency, 11% of contacts showed entrainment at both the word and syllable frequencies, and 4% showed entrainment only to the word frequency. Word entrainment, indicating sensitivity to word structures, was most commonly found in auditory and language-related regions, including insula, middle temporal gyrus, superior temporal gyrus, and supramarginal gyrus. In contrast, evidence for neural entrainment in the hippocampus was weak. Overall, these results support the idea that speech-based SL is largely supported by modality-specific brain regions.

There exists a dynamic interplay among the neural mechanisms that underlie decision-making and memory in the brain, with mounting evidence suggesting that the anterior hippocampus plays a role in how we represent past experiences as well as how we engage in choice behavior. A key question, then, is how the anterior hippocampus represents memories of our choices. Prior research has identified conceptual similarity between choice options as a critical factor influencing hippocampal involvement in decision-making. Building on this, we investigated how remembering chosen versus unchosen options from conceptually similar and dissimilar choice scenarios affects hippocampal memory representations. In a preregistered fMRI study, participants made a series of decisions between pairs of food options that were either conceptually similar or dissimilar and then completed an item recognition memory task for the previously presented options. Using representational similarity analysis, we examined hippocampal overlap during recognition among chosen and unchosen options from both similar and dissimilar choice trials. Our key finding was higher anterior but not posterior hippocampal similarity when remembering options from the conceptually similar compared with conceptually dissimilar trials, and further analysis showed that this was not explained simply by concept overlap. Complementary multivariate whole-brain analysis further revealed neural patterns of covariance that distinguished between memory for chosen/unchosen options across the similar and dissimilar trials. Taken together, these findings suggest that the way the brain-particularly the anterior hippocampus-stores and retrieves memories is profoundly impacted by the context in which deliberation occurs.

Emotional processing is ubiquitous in everyday life, informing goal pursuit not only in response to current demands but also in anticipation of future outcomes. Lateral pFC (LPFC) function supports cognitive control, and emerging evidence suggests a unique role for its anterior-most region-the lateral frontal pole (FPl)-in integrating putatively amygdala-originated emotion signals with goal information. However, whether these organizational properties of LPFC are expressed during the anticipation of future threat remains unknown. Here, we used finite impulse response modeling and pattern similarity analysis to examine dynamic engagement and representational properties of distinct LPFC regions during threat anticipation requiring goal-directed action. Healthy participants (n = 67, 51 female) were scanned during a threat-of-shock paradigm consisting of a prolonged (18 sec) countdown to possible shock administration. Threat unpleasantness and controllability were manipulated orthogonally: In controllable trials, participants could avoid an unpleasant or mild shock by making a successful time-sensitive response; in uncontrollable trials, shocks were administered regardless of performance. LPFC robustly coded for anticipated threat unpleasantness, with FPl showing the strongest modulation by threat unpleasantness and controllability relative to caudal and mid-LPFC regions. While caudal and mid-LPFC maintained independent representations of threat unpleasantness and controllability, FPl held conjunctive threat-and-controllability representations, which were associated with successful motor performance following unpleasant threat anticipation. Stronger conjunctive FPl representations were also associated with greater inverse amygdala-FPl coupling. Together, these findings provide insight into LPFC organization under naturalistic emotional challenges and highlight a key role for FPl in integrating affective and control-related information during threat anticipation to support goal-directed action.

A growing body of evidence indicates that spontaneous, moment-to-moment fluctuations of the EEG alpha power (7-15 Hz) affect perception, with a lower amplitude of alpha oscillations right before the stimulus onset facilitating its detection and visibility. However, whether a similar relationship exists also at the interindividual level has not yet been established. Therefore, the present study aimed to determine whether resting-state alpha power constitutes a robust trait-like predictor of differences in cortical excitability and perceptual abilities. To this end, we used data collected from 302 participants who took part in an EEG recording session and, on separate days, performed a battery of visual tasks and had phosphene and motor thresholds estimated with TMS (here n = 45). Resting-state EEG signals were characterized in terms of both oscillatory (periodic) and background (aperiodic) components. We found that higher overall alpha power predicted higher phosphene thresholds (but not motor thresholds). However, across several behavioral paradigms-using different types of tasks and stimuli, and analyzing both objective accuracy and subjective visibility-we did not find evidence that alpha activity correlated with perceptual abilities. Therefore, although alpha power robustly predicts perception of visual threshold stimuli at the intra-individual level, our study suggests that the relation between alpha power and perception does not extend to the interindividual level.

The human voice is a highly socially relevant auditory stimulus, which has been shown to have a special status, both perceptually and neurally. Perceptual studies have revealed adaptation effects in the behavioral categorization of sounds as either human voice or musical instruments. The current study measured evoked responses using EEG to voice and instrument sounds under passive listening to explore the neural underpinnings of both categorization and context effects. In Experiment 1, vowel utterances (/a/, /o/, /u/, and /i/) and instrumental tones (bassoon, horn, saxophone, and viola) were presented with equal probability in a random sequence. The two sound categories were found to produce reliably distinguishable EEG responses at latencies of between 70 and 280 msec. In Experiment 2, an MMN paradigm resulted in mixed evidence for early neural categorization, with an MMN observed for rare instrumental tones embedded in a random sequence of four different vowels, but no significant MMN for a rare vowel embedded in a random sequence of four different instrumental tones. In Experiment 3, ambiguous voice-instrument morphs were used to show that brain responses could be used to predict the context (voice or instrument sound) in which the morphed sounds were presented. The results show that neural correlates of both categorization (voice vs. nonvoice) and context effects can be observed in EEG responses under passive listening conditions.

Social anxiety is reliably characterized by biases toward avoidance and aversive learning. Here, we examined the neurocomputational processes underlying these biases and examined whether these biases persist across different social contexts. A sample of 154 participants (84% female, mean age = 20.42) with subclinical to minimal levels of social anxiety completed a probabilistic selection task in two contexts: performing alone and under social scrutiny. We analyzed frontal midline theta (FM-theta) EEG activity to uncover neurocomputational processes underlying aversive learning in social anxiety. Results showed that participants performed more accurately alone and predominantly preferred a win-stay strategy. Social anxiety led to an increased use of both win-stay and lose-switch strategies (e.g., repeating a choice after receiving positive feedback or switching to a different choice after receiving negative feedback, respectively). In response to negative feedback, FM-theta power predicted post-error slowing, an effect heightened in socially anxious participants. Punishment-based learning was stronger than reward-based learning in all participants, but social anxiety amplified this effect, particularly when participants performed alone. Our findings suggest that social anxiety modulates FM-theta activity in aversive control, promoting reactive avoidance in decision-making. This mechanistic insight links social anxiety to a cascade of orienting, control, and learning biases and positions FM-theta as a potential neural target for interventions aimed at reducing maladaptive avoidance and enhancing adaptive learning in socially anxious individuals.

Attentional selectivity focuses on what is currently relevant. Relevance changes frequently in everyday life, triggering rapid reassignments of attentional priorities. Such reassignments are often not associated with behavioral changes and are thus difficult to assess objectively. Here, we measured rapid, covert switches between preparatory task settings (attentional templates) in visual search, as they occurred in real time. Participants searched for color-defined targets in search displays that appeared unpredictably either early (after 700 msec) or late (after 1500 msec) on each trial. In Experiment 1, early and late targets were defined by different colors. Participants first had to activate a template for the early target color and then switch to a template for the late target color if no early search display appeared. In Experiment 2, cues signaled whether the initial target template had to be maintained or changed. Template activation states were tracked with N2pc components to rapid sequences of irrelevant probes matching either the early or late target color. A template for the early target color was active from about 300 msec before the expected arrival of early search displays, followed by a template switch. Switches based on endogenous temporal expectations emerged more gradually in time than switches in response to external cues. Presenting cues in Experiment 2 triggered a temporary search template deactivation even when the target color remained unchanged, indicating that template maintenance is subject to an attentional blink. Results demonstrate that rapid switches between attentional templates in visual search can be tracked with high temporal precision.

Although listeners can enhance perception by using prior knowledge to predict the content of degraded speech signals, this process can also elicit "misperceptions." The neurobiological mechanisms responsible for these phenomena remain a topic of debate. There is relatively consistent evidence for involvement of the bilateral posterior superior temporal gyri (pSTG) in speech perception in noise; however, a role for the left premotor cortex (PMC) is debated. In this study, we employed transcranial magnetic stimulation (TMS) and a prime-probe paradigm for the first time to investigate causal roles for the left PMC and pSTG in speech perception and misperception. To produce misperceptions, we created partially mismatched pseudosentence probes via homophonic nonword transformations (e.g., She moved into her apartment soon after signing the lease-Che moffed inso har apachment sool amter siphing tha leals). All probe sentences were then spectrotemporally degraded and preceded by a clear prime sentence. Compared with a control site (vertex), inhibitory stimulation of the left pSTG selectively disrupted priming of real but not pseudosentences. However, inhibitory stimulation of the left PMC did not significantly influence perception of either real sentences or misperceptions of pseudosentences. These results confirm a role for the left pSTG in the perception of degraded speech. However, they do not support a role for the left PMC in either lexical or sublexical processing during perception of degraded speech using ecologically valid sentence stimuli. We discuss the implications of these findings for neurobiological models of speech perception.

Harmonic expectation is an important mediator of musical experience. EEG research has identified event-related potential (ERP) components associated with expectation, including the early (right) anterior negativity (E(R)AN), which is theorized to index harmonic surprisal with reference to long-term memory of the statistical structure of music. However, the role of top-down influences on harmonic predictions remains underexplored. One specific influence concerns how a given harmony can be interpreted in different ways, depending on its syntactic role in a musical context. We present data from a novel paradigm that cues listeners to the syntactic structure of the stimuli (but not whether they contain improbable events). Our main result revealed larger E(R)AN amplitudes for improbable chords when listeners knew that additional context would follow a surprising harmony; P3a and P600 amplitudes were also larger in such cases. Using the theoretical framework of predictive coding, we propose that, in such cases, listeners assign higher precision to their predictions, leading to larger prediction errors as indexed by the E(R)AN, P3a, and P600 ERP components, and that prior context alone does not fully explain how unpredictable events are processed. Musical surprisal arises from a dynamic interplay between bottom-up cues and a listener's top-down anticipation within specific syntactic contexts.

In mixed-features search tasks, the target-defining feature changes unpredictably across trials. Responses are faster when the same feature is repeated across successive trials. This effect, known as intertrial priming of pop-out (PoP), suggests that the selection of a perceptually salient singleton target is modulated by the properties of the preceding search array. To investigate whether PoP can be observed in touch, we developed a mixed-features search task in which a singleton target was presented simultaneously with three homogeneous distractors to the index and middle fingers of the left and right hands. The target-defining vibrotactile frequency varied across trials (either a high-frequency target among low-frequency distractors or vice versa) so that on half of the trials, the singleton frequency was repeated on successive trials, while on the other half, it was alternated. To investigate the presence and the mechanisms underlying PoP in touch, behavioral and ERPs were recorded. Specifically, the N140cc component was used as a marker of spatial selective attention in touch. In line with visual search studies, improved performance for both RTs and accuracy was observed when the singleton target feature was repeated across trials than when it was alternated. Importantly, the N140cc component showed larger amplitudes on repetition compared with change trials, demonstrating that the attentional selection of a tactile target was modulated by PoP. Results demonstrate for the first time that PoP effects emerge also during the search for a tactile target.

Working memory (WM) involves continuous and dynamic processes, including encoding, maintenance, and retrieval. While many studies have focused on the maintenance of WM information, encoding strategies also impact WM performance and can be shaped by the presentation format of stimuli. However, how presentation formats modulate neural responses across WM stages remains unclear. To address this issue, we conducted an EEG study examining the effects of presentation formats (simultaneous, location-sequential, and center-sequential presentation) and WM loads (one and three abstract shapes). Behavioral results showed longer RTs for the location-sequential than for the center-sequential format. Additionally, the recency effects observed in both sequential conditions reflect the influence of ordinal information. EEG results revealed distinct load-dependent alpha activity patterns across presentation formats during WM maintenance. Simultaneous presentations exhibited a persistent decrease in alpha power, whereas both sequential presentations exhibited an initial decrease followed by a subsequent increase. During sequential encoding, alpha power decreased cumulatively with each additional item in the location-sequential format, but not in the center-sequential format. At retrieval, the probe elicited a load-dependent negative potential (i.e., the N3rs) across all formats. The N3rs load modulation was stronger for simultaneous presentations than sequential ones and was more pronounced for earlier positions than for the last position in sequential presentations. In conclusion, our findings demonstrate that the spatial and temporal order information embedded in presentation formats modulates load-dependent neural responses across WM stages. These effects extend beyond maintenance to encoding and retrieval, highlighting the influence of presentation formats on WM neural dynamics.

Subjective features of memory are often treated as secondary to the objective content of remembered events. However, growing evidence suggests that these features actively shape how memories are constructed, experienced, and used. Rather than treating visual perspective as a peripheral correlate of subjectivity, this review positions it as a key mechanism that shapes the memory. Because perspective can be flexibly controlled and reliably measured, it offers a unique window into how retrieval goals interact with mental simulation to produce vivid and emotionally resonant recollections. Drawing on behavioral and neuroimaging research, this review shows that visual perspective determines the spatial framing of memory and the emotional and sensory qualities of recollection. Focusing on the posterior parietal cortex, it outlines distinct roles for the angular gyrus (AG) and the precuneus in supporting perspective-dependent retrieval. The AG contributes to the selection and maintenance of a retrieval perspective, integrating perceptual and conceptual features into a coherent scene. In contrast, the precuneus supports spatial transformation and modulates the vividness, emotional tone, and embodied character of recollection, particularly when individuals recall events from a nondominant or shifted perspective. Together, these findings position visual perspective as a central mechanism in the construction of subjectivity. Understanding how perspective shapes the process of remembering provides insight into how memory supports emotion regulation, mental simulation, and the continuity of the self across time.

Metacontrol states involve adapting cognitive control to contextual demands-being more flexible in frequent task-switching environments or more stable in those with infrequent switching. While these metacontrol states can be engaged proactively in anticipation or reactively in response to specific contexts, how these two metacontrol modes interact remains unclear. To address this question, we recorded EEG measures of brain activity during a task-switching paradigm in which we manipulated proactive metacontrol via block-level incentives (baseline vs. penalty). Within blocks, some images occurred more frequently on switch trials and others on repeat trials, which we expected to elicit reactive metacontrol adjustments. This design enabled us to investigate how block-level proactive metacontrol influences reactive metacontrol in response to image-specific switch demands. We found that during the penalty block, designed to enhance proactive processing, greater slow negative-polarity ERP waves (contingent negative variation waves) were elicited before the onset of the image and task cue, which has been associated with preparatory attention and improved task-switching efficiency. Moreover, the penalty block showed image-specific metacontrol adjustments or "reactive metacontrol," as reflected by modulations in the N2 and the late positive component EEG waves during image and task-cue presentation. Together, these findings support theoretical frameworks suggesting that heightened preparatory attentional control-such as that induced by penalty-based incentives-can serve to enhance stimulus feature-binding mechanisms critical for reactive metacontrol learning and instantiation.