Erich Schröger

Theories of word production rely heavily on semantic context effects. For example, when pictures are named repeatedly and sorted by semantic category, it takes longer to name them than when they are named in an intermixed manner. Wöhner et al. (2021) found that semantic interference in blocked-cyclic naming was approximately three times greater for sounds (e.g., barking) than for pictures (e.g., a dog). This study explored possible reasons for this differential interference pattern. When the stimuli were presented briefly, the differential interference was replicated, ruling out the possibility that it results from a large overlap between stimulus processing and phonological response preparation. When the sounds and pictures were replaced with spoken and written words that the participants translated into their second language, the size of the interference was similar, showing that the differential pattern does not result from different stimulus modalities (auditory vs. visual). When participants typed their responses, the differential interference was replicated again, showing that it does not depend on a certain response modality (spoken vs. written). Additionally, pupil dilation data suggest that sounds, compared with pictures, may activate additional representations that contribute to the interference. Overall, the data imply that semantic interference in word production is shaped by early, stimulus-specific, perceptual and semantic “lead-in” processes that precede lexical selection. More attention should be given to these early processes in word production research.

The human auditory system rapidly encodes auditory regularities. Evidence comes from the oddball paradigm, in which frequent (standard) sounds are occasionally replaced with a rare (deviant) sound. Deviants relative to standards typically elicit signs of prediction error (e.g., MMN and P3a). It is, however, less clear whether deviants, which also bear predictive information but are encountered less often than standards, might inform auditory prediction. To investigate this, naïve participants listened to sound sequences constructed according to a new, modified version of the oddball paradigm: two kinds of deviants differing in their probability of repetition yield the sound actually following a deviant either conditionally likely or unlikely. As this sound is either the same deviant (repetition) or a standard (no repetition), it is either unlikely or likely with respect to the global stimulus probability at the same time. In an active deviant detection task, we replicated previous behavioural findings, demonstrating that predictive information carried by deviants (conditional probability) is extracted when behaviourally relevant. Our analyses further reveal that respective response time effects increase over the course of the task. However, in a passive listening setting, both MMN and P3a were confined to violations of rules based on global probability, while not being sensitive to conditional probability. Though some sensitivity to conditional probability had been observed in a previous study, these effects were tiny compared to those of global probability. Thus, the auditory system seems to mainly rely on rules that are encountered frequently (standard regularity), at least during passive listening.

The unpredicted omission of expected sound, that is “silence”, elicits omission N1, N2 and P3 (early and late oN1, oN2, oP3) event-related potential (ERP) and pupil dilation responses (PDR), which are interpreted as prediction error signals located along different processing levels. This study aims to investigate whether these responses to unpredicted silence can also be elicited by the unpredicted continuation of sound, that is, the “absence” of expected silence. A prediction error response to the absence of silence would indicate that silence was predicted including the levels of processing on which a prediction of silence was established. Participants (27 women, 10 men) pressed a button every 1-2s while exposed to continuous Brownian noise. Button presses predictably (88% of trials), randomly (50% of trials) or never (0% of trials; motor-control) interrupted the noise. EEG and pupil diameter data were recorded. We found that the unpredicted absence of a silent interval in the noise elicited late oN1 (~150ms) and oN2, oP3 and PDR omission prediction error responses. However, we did not find an early oN1 (~100ms). Predictive representations of silence can be established at the level of categorical sensory processing (late oN1) and at the levels of later, higher cognitive processing and attention (oN2, oP3, and PDR), but not at the level of feature-based, early cortical sensory processing (early oN1), possibly because the absence of features cannot easily be encoded. These results suggest that silence is represented not only as the absence of sound but also as a predictable event in itself.

The human brain anticipates the sensory consequences of an action and generates a prediction error (PE) signal when the intended action effect does not occur. This study investigated auditory event‐related potential PE markers based on whether participants intended to perform a specific action or produce a specific action effect. Participants were instructed to press a left or right button to produce low‐ or high‐pitched tones, following a visual pattern. The instructions, actions and tone sequences were identical for all participants. The visual patterns differed in two groups: In the action‐effect intention group, the visual pattern consisted of ‘notes’ (indicating low/high pitch). In the action intention group, the visual pattern consisted of ‘letters’ (indicating left/right button‐press). In both groups, a button‐press occasionally failed to produce the associated tone (incongruent sounds). The key finding was that these incongruent sounds elicited an enhanced auditory N1 component compared to congruent sounds only in the ‘notes’ group. We propose that participants in the ‘notes’ group selected their actions based on the intended action effect, which induced a predictive sensory representation of the expected tone. A violation of this prediction resulted in the early PE, reflected in the auditory N1. Later PE responses, specifically the N2b and P3 components, were observed in both groups. This suggests that action‐effect associations were represented, and their violation was processed at a conceptual level even in the ‘letters’ group. These results support theories postulating that event representations integrate features of stimuli, actions and their associated outcomes.

The mismatch negativity (MMN) is a well-studied event-related potential (ERP) component in the EEG reflecting deviance detection in the auditory modality. It taps into the basic functioning of auditory regularity processing. The auditory multi-feature paradigm is widely used in sensitive and special populations to measure MMN simultaneously for different sound features in a short amount of time. It is consensus in the field that both adaptation and genuine deviance detection contribute to the “classic” MMN computed as deviant minus standard ERP difference. However, no attempts have yet been made to disentangle adaptation from “genuine” MMN in the multi-feature paradigm. Here, we propose a cascadic control condition for the auditory multi-feature paradigm that controls for adaptation and physical differences between standard and deviant sounds. Using this new paradigm, we measured genuine MMN, computed as deviant minus control ERP difference, for frequency, location, intensity, and duration deviants. Genuine MMN amplitudes for frequency and location were found substantially smaller than in traditional paradigms. No genuine intensity MMN and only a later and smaller genuine duration MMN were found. The results suggest stronger contributions of adaptation than in the traditional oddball paradigm. Controlling for adaptation is particularly relevant in research concerning predictive processing and the use of MMN as a biomarker related to impaired NMDA receptor synaptic transmission as observed in schizophrenia. The presented multi-feature cascadic control condition enables the measurement of genuine MMN, which presumably reflects higher-order cortical computations, such as predictive processing, still in a short amount of time.

When an action does not yield the sensory action effect associated with it, prediction error (PE) signals are generated. The present study investigates auditory event-related potential (ERP) markers of PE for violations of strong action-effect couplings as a function of whether the participants’ intention focuses on a particular action or a particular action effect. Participants produced high- and low-pitched tones by left and right button presses according to a pattern of visual stimuli. While the instruction as well as the action and tone sequences produced by the participants were identical, the type of intention induced by the visual symbols differed (in a between-subject design): In the action-effect intention group, the pattern consisted of “notes” (for high/low pitch), in the action intention group it consisted of “letters” (for left/right button-press). Occasionally, a button-press did not produce the associated sensory action effect. These incongruent sounds elicited an enhanced auditory N1 compared to congruent sounds in the “notes” but not the “letters” group which we interpret as PE signal. Actions selected by the intended action effect in the “notes” group presumably induced a predictive sensory representation of the action outcome, its violation resulting in an early PE at the level of the auditory N1. N2b and P3 were elicited in both groups. This suggests that the respective action-effect couplings were represented, and their violation processed at a conceptual level also in the “letters” group. These results support theories postulating that event representations bind together features of stimuli, actions, and associated outcomes.

Biodiversity is crucial for human health and well‐being. Perceived biodiversity—people's subjective experience of biodiversity—seems to be particularly relevant for mental well‐being. Using photographs and audio recordings of forests that varied in levels of biodiversity, we conducted two sorting studies to assess how people perceive visual and acoustic diversity and whether their perceptions align with species richness and proxies for forest structural diversity (‘actual diversity’). Per study, 48 participants were asked to sort the stimuli according to any similarity‐based sorting criteria they liked (‘open sorts’) and perceived diversity (‘closed sorts’). The main perceived visual forest characteristics identified by participants in the open visual sorts were vegetation density, light conditions, forest structural attributes and colours. The main perceived acoustic forest characteristics identified in the open acoustic sorts comprised bird song characteristics, physical properties such as volume, references to the time of day or seasonality and evoked emotions. Perceived visual and acoustic diversity were significantly correlated with actual visual and acoustic diversity, respectively. We further computed several objective visual and acoustic diversity indices from the photos and audio recordings, for example, a Greenness Index or the Acoustic Complexity Index, and assessed their relevance for perceived and actual diversity. While all acoustic diversity indices were significantly associated with perceived and actual acoustic diversity, for the visual sense, the Greenness Index successfully captured both perceived and actual visual diversity. Our results suggest that people can perceive variations in biodiversity levels. Our identified visual and acoustic forest characteristics may help to better understand perceived diversity and how it differs from how diversity is measured in biological studies. We present one visual and several acoustic diversity indices that quantify aspects of perceived and actual diversity. These indices may serve as cost‐efficient tools to manage and plan greenspaces to promote biodiversity and mental well‐being. Read the free Plain Language Summary for this article on the Journal blog.

Recent theories describe perception as an inferential process based on internal predictive models that are adjusted by prediction violations (prediction error). Two modulations of the auditory N1 event‐related brain potential component have been interpreted as reduced or enhanced prediction error for predictable sensory input: The sound‐related N1 component is attenuated for self‐generated sounds compared to the N1 elicited by externally generated sounds (N1 suppression). An omission‐related component in the N1 time‐range is elicited when the self‐generated sounds are occasionally omitted (omission N1). We wanted to confirm that both N1 suppression and omission N1 are sensitive to the predictability of sound identity, as reported in the literature. We manipulated the predictability of sound identity in a self‐generation paradigm in which button presses in one condition always produced the same sound or in another condition produced a sound randomly selected from a large set of sounds. Omission N1 was modulated by manipulating the predictability of sound identity but surprisingly N1 suppression was not. This contradicts previous reports, challenges prediction‐related interpretations of the N1 suppression, and supports alternative explanations for N1 suppression like action‐related unspecific sensory gating.

When a picture is repeatedly named in the context of semantically related pictures (homogeneous context), responses are slower than when the picture is repeatedly named in the context of unrelated pictures (heterogeneous context). This semantic interference effect in blocked-cyclic naming plays an important role in devising theories of word production. Wöhner, Mädebach, and Jescheniak [Wöhner, S., Mädebach, A., & Jescheniak, J. D. Naming pictures and sounds: Stimulus type affects semantic context effects. Journal of Experimental Psychology: Human Perception and Performance, 47, 716–730, 2021] have shown that the effect is substantially larger when participants name environmental sounds than when they name pictures. We investigated possible reasons for this difference, using EEG and pupillometry. The behavioral data replicated Wöhner and colleagues. ERPs were more positive in the homogeneous compared with the heterogeneous context over central electrode locations between 140–180 msec and 250–350 msec for picture naming and between 250 and 350 msec for sound naming, presumably reflecting semantic interference during semantic and lexical processing. The later component was of similar size for pictures and sounds. ERPs were more negative in the homogeneous compared with the heterogeneous context over frontal electrode locations between 400 and 600 msec only for sounds. The pupillometric data showed a stronger pupil dilation in the homogeneous compared with the heterogeneous context only for sounds. The amplitudes of the late ERP negativity and pupil dilation predicted naming latencies for sounds in the homogeneous context. The latency of the effects indicates that the difference in semantic interference between picture and sound naming arises at later, presumably postlexical processing stages closer to articulation. We suggest that the processing of the auditory stimuli interferes with phonological response preparation and self-monitoring, leading to enhanced semantic interference.

Biodiversity can foster mental well-being. Little is known, however, about mental well-being effects of acoustic diversity, and how natural soundscapes contribute to a sense of place. To test this, we conducted an experimental study with 195 German residents who listened to two forest soundscapes with low or high vocalising animal richness (actual acoustic diversity). As a manipulation of sense of place, recordings were either from local, temperate forests or non-local, tropical forests. For each recording, we assessed short-term changes in mental well-being, perceived stress, subjective attention, perceived restorativeness, awe, familiarity and pleasantness. Participants’ further rated each recording according to perceived animal richness and perceived overall acoustic diversity that enabled participants to rate acoustic diversity based on their own criteria.Actual acoustic diversity was significantly correlated with perceived animal richness and perceived overall acoustic diversity. Well-being effects, however, differed for actual and perceived diversity as well as for the perceived diversity metrics. Higher actual animal richness evoked more feelings of awe in local (temperate) forests. Perceived animal richness was associated with greater affect balance, decreased negative emotions and increased subjective attention, while perceived overall acoustic diversity was negatively associated with affect balance and positive emotions. Recordings from local (temperate) forests were more familiar and pleasant to participants, compared to non-local (tropical) forests recordings. Listening to local forest soundscapes further resulted in greater feelings of awe, and they were perceived as more restorative. Overall, forest soundscapes with higher animal species richness were associated with greater mental well-being. Participants also showed greater well-being responses for local soundscapes probably through feeling more attached to familiar environments. Forests should therefore be managed to provide sufficient niches for a variety of vocalising animal species. Conservation of local species communities may thereby foster both biodiversity and human mental health.