Classes Of Stimuli Research Articles

Advancing research on unconscious priming: When can scientists claim an indirect task advantage?

Current literature holds that many cognitive functions can be performed outside consciousness. Evidence for this view comes from unconscious priming. In a typical experiment, visual stimuli are masked such that participants are close to chance performance when directly asked to which of two categories the stimuli belong. This close-to-zero sensitivity is seen as evidence that participants cannot consciously report the category of the masked stimuli. Nevertheless, the category of the masked stimuli can indirectly affect responses to other stimuli (e.g., reaction times or brain activity)-an effect called priming. The priming effect is seen as evidence for a higher sensitivity to the masked stimuli in the indirect responses as compared with the direct responses. Such an apparent difference in sensitivities is taken as evidence that processing occurred unconsciously. But we show that this "standard reasoning of unconscious priming" is flawed: Sensitivities are not properly compared, creating the wrong impression of a difference in sensitivities even if there is none. We describe the appropriate way to determine sensitivities, replicate the behavioral part of a landmark study, develop methods to estimate sensitivities from reported summary statistics of published studies, and use these methods to reanalyze 15 highly influential studies. Results show that the interpretations of many studies need to be changed and that a community effort is required to reassess the vast literature on unconscious priming. This process will allow scientists to learn more about the true boundary conditions of unconscious priming, thereby advancing the scientific understanding of consciousness. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Salience is in the brain of the beholder: ERPs reflect acoustically salient variables

A recent paper by Boswijk, Loerts & Hilton (Boswijk et al., 2020) in this journal discusses how technological advances allow us to explore the cognitive processing of so-called salient linguistic features, and how this could provide us with quantifiable measures of ‘salience’. The paper concludes that, although promising, the used measure of pupil dilation seems to be limited as a measure for linguistic salience, and therefore refers future research to other measures, specifically Event Related Potentials (ERPs). In this paper we therefore replicate the Boswijk et al. study using the ERP measure with the hypothesis that linguistic salience evokes distinct ERP components. We use the same materials that were used in the Boswijk et al. (2020) paper to observe changes in Dutch participants' pupil sizes when listening to stimuli containing salient and non-salient variants of linguistic variables.Using Generalized Additive Mixed Modelling (GAMM), we find distinct responses for five of six stimuli categories. We consider our findings in light of the literature on linguistic salience and discuss how our findings relate to the Boswijk et al. (2020) study. We find that ERPs provide a more fine-grained measure of theoretically salient stimuli.

Electromagnetic Finite-Element Modeling of Induction Effects for Buried Objects in Magnetic Soils

A frequency-based finite element (FE) framework has been developed to predict and understand the response of an electromagnetic induction (EMI) sensor due to buried targets. The EMI sensor is used to detect buried targets in magnetic nonconducting soils. The framework was verified with an analytical model that utilizes dipole approximations. The framework was then used to predict the electromagnetic (EM) response due to interrelated stimuli and properties. The results indicate that the sensor was not sensitive to small variations (0–200 mm) in the standoff height and lateral positions, and only showed a significant change in the response due to stand-off variations that were greater than 200 mm. This low sensitivity to minor variations in standoff height and lateral position signify that there are critical distances related to the EM response of buried objects. The response to different target conductivities and permeabilities was also investigated for steel and aluminum targets. The lower conductivity steel targets had EM responses, where the inductive limit was reached at higher frequencies than the higher conductivity aluminum targets. Variations in target permeabilities for steel showed that as permeabilities increased, the frequencies at which the inductive limit was reached also increased. This verified predictive approach can provide a methodology to characterize the EM response of buried objects for a broad class of buried object EM properties, geometries, and input stimuli.

Supplemental Material for Classification of Three-Dimensional Integral Stimuli: Accounting for a Replication and Extension of Nosofsky and Palmeri (1996) With a Dual Discrimination Invariance Model

Supplemental Material for Classification of Three-Dimensional Integral Stimuli: Accounting for a Replication and Extension of Nosofsky and Palmeri (1996) With a Dual Discrimination Invariance Model

Chapter 10 - Visual objects and their colors

The ventral temporal cortex hosts key regions for the high-level visual processing of object shape and color. These areas represent nodes of large-scale neural circuits dedicated to object recognition. In the language-dominant hemisphere, some of these regions communicate with the language systems; by assigning verbal labels to percepts, these circuits speedup stimulus categorization, and permit fast and accurate interindividual communication. By impairing the functioning of these circuits, neurological damage may provoke disabling disorders of the processing of visual objects and of their colors. Brain damage of vascular, degenerative, toxic, or traumatic origin can induce deficits at different levels of visual processing, from the building of shape- or wavelength-invariant percepts, to their connections with semantic knowledge and with the appropriate lexical entry. After an overview of the neuroimaging of domain-preferring regions for object shape and color in the ventral temporal cortex, this chapter reviews evidence from historical and recent cases of acquired visual agnosia and color processing deficits. A recurrent motif emerging from patients' patterns of performance and lesion locations is the existence of caudo-rostral gradients in the ventral occipito-temporal cortex, spanning from more perceptual to more cognitive stages of processing.

Effect of Environment-Related Cues on Auditory Distance Perception in the Context of Audio-Only Augmented Reality

Audio-only augmented reality consists of enhancing a real environment with virtual sound events. A seamless integration of the virtual events within the environment requires processing them with artificial spatialization and reverberation effects that simulate the acoustic properties of the room. However, in augmented reality, the visual and acoustic environment of the listener may not be fully mastered. This study aims to gain some insight into the acoustic cues (intensity and reverberation) that are used by the listener to form an auditory distance judgment, and to observe if these strategies can be influenced by the listener’s environment. To do so, we present a perceptual evaluation of two distance-rendering models informed by a measured Spatial Room Impulse Response. The choice of the rendering methods was made to design stimuli categories in which the availability and reproduction quality of acoustic cues are different. The proposed models have been evaluated in an online experiment gathering 108 participants who were asked to provide judgments of auditory distance about a stationary source. To evaluate the importance of environmental cues, participants had to describe the environment in which they were running the experiment, and more specifically the volume of the room and the distance to the wall they were facing. It could be shown that these context cues had a limited, but significant, influence on the perceived auditory distance.

Category-Biased Neural Representations Form Spontaneously during Learning That Emphasizes Memory for Specific Instances.

Category learning, learning to sort a set of stimuli into categories or groups, can induce category biases in perception such that items in the same category are perceived as more similar than items from different categories. To what degree category bias develops when learning goals emphasize individuation of each stimulus and whether the bias emerges spontaneously during learning itself rather than in response to task demands is unclear. Here, we used functional MRI (fMRI) during encoding to test for category biases in neural representations of individual stimuli during learning. Human participants (males and females) encountered face-blend stimuli with unique first names and shared family names that indicated category membership. Participants were instructed to learn the full name for each face. Neural pattern classification and pattern similarity analyses were used to track category information in the brain. Results showed that stimulus category could be decoded during encoding across many frontal, parietal, and occipital regions. Furthermore, two stimuli from the same category were represented more similarly in the prefrontal cortex than two stimuli from different categories equated for physical similarity. These findings illustrate that a mere presence of category label can bias neural representations spontaneously during encoding to emphasize category-relevant information, even in the absence of explicit categorization demands and when category-irrelevant information remains relevant for task goals.SIGNIFICANCE STATEMENT Entities belonging to the same category are perceived as being more similar than entities belonging to different categories. Here, we show that neural representations highlighting category-relevant information form spontaneously during encoding. Notably, the presence of a category label led to neural category bias although participants focused on remembering individual stimuli and category-irrelevant stimulus features remained important for explicit task goals. These results may inform our understanding of bias in general and suggest that bias may emerge when category information is present even when one's explicit focus is on individuals.

Visual Discomfort and Variations in Chromaticity in Art and Nature.

Visual discomfort is related to the statistical regularity of visual images. The contribution of luminance contrast to visual discomfort is well understood and can be framed in terms of a theory of efficient coding of natural stimuli, and linked to metabolic demand. While color is important in our interaction with nature, the effect of color on visual discomfort has received less attention. In this study, we build on the established association between visual discomfort and differences in chromaticity across space. We average the local differences in chromaticity in an image and show that this average is a good predictor of visual discomfort from the image. It accounts for part of the variance left unexplained by variations in luminance. We show that the local chromaticity difference in uncomfortable stimuli is high compared to that typical in natural scenes, except in particular infrequent conditions such as the arrangement of colorful fruits against foliage. Overall, our study discloses a new link between visual ecology and discomfort whereby discomfort arises when adaptive perceptual mechanisms are overstimulated by specific classes of stimuli rarely found in nature.

Stimuli Induced Uptake of Protein-Like Peptide Brush Polymers.

Recently, we presented a strategy for packaging peptides as side-chains in high-density brush polymers. For this globular protein-like polymer (PLP) formulation, therapeutic peptides were shown to resist proteolytic degradation, enter cells efficiently and maintain biological function. In this paper, we establish the role charge plays in dictating the cellular uptake of these peptide formulations, finding that peptides with a net positive charge will enter cells when polymerized, while those formed from anionic or neutral peptides remain outside of cells. Given these findings, we explored whether cellular uptake could be selectively induced by a stimulus. In our design, a cationic peptide is appended to a sequence of charge-neutralizing anionic amino acids through stimuli-responsive cleavable linkers. As a proof-of-concept study, we tested this strategy with two different classes of stimuli, exogenous UV light and an enzyme (a matrix metalloproteinase) associated with the inflammatory response. The key finding is that these materials enter cells only when acted upon by the stimulus. This approach makes it possible to achieve delivery of the polymers, therapeutic peptides or an appended cargo into cells in response to an appropriate stimulus.

Individual differences in music reward sensitivity influence the perception of emotions represented by music

Although music is one of the most important sources of pleasure for many people, there are considerable individual differences in music reward sensitivity. Behavioral and neurobiological characterizations of music reward variability have been topics of increasing scientific interest over the last two decades. However, it is not clear how differences in music reward sensitivity might influence the perception of emotions represented by music and, specifically, how music reward sensitivity could influence subjective music evaluation when the affective valence of music is considered. In the present study, we investigated the relationship between music reward sensitivity and the perception of emotions in music, taking into account the emotional category of stimuli (pleasant, neutral, or unpleasant music clips). Music reward and emotion perception were also explored as a function of gender, musicianship, and music discrimination skills. We used the Barcelona Music Reward Questionnaire and the previously validated Film Music Stimulus Set (FMSS); participants rated FMSS excerpts for affective dimensions (valence, energy, and tension arousal) and discrete emotions (happiness, anger, fear, tenderness, and sadness). Our results showed that music reward was the main factor influencing FMSS evaluation, particularly for excerpts associated with positive affect. Gender had an important influence on evaluations linked to the negative pole of emotions, and music discrimination skills seemed to be associated with cognitive aspects of music analysis, rather than with the emotional architecture of pleasant music excerpts. Our findings highlight the need to consider music reward sensitivity and gender in studies of music and emotion, and open the possibility of using the FMSS in studies exploring the neurobiological and psychosocial bases of music emotion.

TEACHING SYMBOLIC RELATIONS IN DOWN SYNDROME THROUGH EQUIVALENCE-BASED INSTRUCTION: A CASE STUDY

A procedure for establishing equivalence classes in a participant with Down syndrome was implemented. The classes were composed of written words (A), pictorial representations (B), digit numbers (C), and auditory words (D) representing metro stations. In the training phase, we implemented a successful procedure for enhancing perceptual discrimination of written words when presented as sample stimuli (A), and we established a reduced number of stimulus relations: AB, BC, DA, from which the participant was able to derive full stimulus classes that included derived relations between stimuli that had not been trained before: BA, CB, AC, CA, DB, and DC. The study encompassed a total of 7 sessions, and by the end these, the participant showed correct mappings between written words, pictures, auditory words, and digits. We detail adaptations to traditional training procedures that facilitated learning in the participant with Down syndrome. We argue that procedures based on equivalence instruction are beneficial for the establishment of symbolic and communicative repertoires in individuals with developmental disabilities.

DEPRESIVNOSTI VIZUELNO PAMĆENJE SPECIFIČNIH STIMULUSA (EMOTIKONA)

Depression is a state of reduced psychophysical activity that is accompanied by various changes in cognitive, emotional and social functioning. Previous studies have found that depression leads to changes in the recognition of the emotions of others, makes it difficult to direct attention and significantly impairs visual memory. The main goal of this research is to examine the relations between depressive symptoms and visual memory of specific stimuli that show emotions. We also want to examine whether the intensity of depressive symptoms is related to longer reaction time in the experimental task, as well as whether the accuracy of the emoticon’s visual memory depends on the set size. The research was conducted on a sample of 84 participants, students of Faculty of Philosophy in Banja Luka (90% female). The PHQ-9 questionnaire was used to assess depressive symptoms. Visual memory task was created in SuperLab 4.1. for Windows.The results show that there is a partial contribution of moderate depression to the accuracy of emoticon memory with sadness expression. No partial contribution of any category of depression to the memory accuracy of emoticons with the expression of happiness has been determined. A statistically significant negative correlation for the category of “sad” stimuli was obtained between the expression of depressive symptoms and the response time in the experimental task, while no statistically significant correlation was obtained for the second category of stimuli. It was also found that the number of errors increases with the set size. These results can be explained by negative bias and cognitive load in information processing. Key words: visual memory, depression, emoticons, expression of happiness, expression of sadness

Cortical Processing of Binaural Cues as Shown by EEG Responses to Random-Chord Stereograms

Spatial hearing facilitates the perceptual organization of complex soundscapes into accurate mental representations of sound sources in the environment. Yet, the role of binaural cues in auditory scene analysis (ASA) has received relatively little attention in recent neuroscientific studies employing novel, spectro-temporally complex stimuli. This may be because a stimulation paradigm that provides binaurally derived grouping cues of sufficient spectro-temporal complexity has not yet been established for neuroscientific ASA experiments. Random-chord stereograms (RCS) are a class of auditory stimuli that exploit spectro-temporal variations in the interaural envelope correlation of noise-like sounds with interaurally coherent fine structure; they evoke salient auditory percepts that emerge only under binaural listening. Here, our aim was to assess the usability of the RCS paradigm for indexing binaural processing in the human brain. To this end, we recorded EEG responses to RCS stimuli from 12 normal-hearing subjects. The stimuli consisted of an initial 3-s noise segment with interaurally uncorrelated envelopes, followed by another 3-s segment, where envelope correlation was modulated periodically according to the RCS paradigm. Modulations were applied either across the entire stimulus bandwidth (wideband stimuli) or in temporally shifting frequency bands (ripple stimulus). Event-related potentials and inter-trial phase coherence analyses of the EEG responses showed that the introduction of the 3- or 5-Hz wideband modulations produced a prominent change-onset complex and ongoing synchronized responses to the RCS modulations. In contrast, the ripple stimulus elicited a change-onset response but no response to ongoing RCS modulation. Frequency-domain analyses revealed increased spectral power at the fundamental frequency and the first harmonic of wideband RCS modulations. RCS stimulation yields robust EEG measures of binaurally driven auditory reorganization and has potential to provide a flexible stimulation paradigm suitable for isolating binaural effects in ASA experiments.

Groupitizing modifies neural coding of numerosity.

Numerical estimation of arrays of objects is faster and more accurate when items can be clustered into groups, a phenomenon termed “groupitizing.” Grouping can facilitate segregation into subitizable “chunks,” each easily estimated, then summed. The current study investigates whether spatial grouping of arrays drives specific neural responses during numerical estimation, reflecting strategies such as exact calculation and fact retrieval. Fourteen adults were scanned with fMRI while estimating either the numerosity or shape of arrays of items, either randomly distributed or spatially grouped. Numerosity estimation of both classes of stimuli elicited common activation of a right lateralized frontoparietal network. Grouped stimuli additionally recruited regions in the left hemisphere and bilaterally in the angular gyrus. Multivariate pattern analysis showed that classifiers trained with the pattern of neural activations read out from parietal regions, but not from the primary visual areas, can decode different numerosities both within and across spatial arrangements. The behavioral numerical acuity correlated with the decoding performance of the parietal but not with occipital regions. Overall, this experiment suggests that the estimation of grouped stimuli relies on the approximate number system for numerosity estimation, but additionally recruits regions involved in calculation.

Sounds familiar(?): Expertise with specific musical genres modulates timing perception and micro-level synchronization to auditory stimuli

Musical expertise improves the precision of timing perception and performance – but is this expertise generic, or is it tied to the specific style(s) and genre(s) of one’s musical training? We asked expert musicians from three musical genres (folk, jazz, and EDM/hip-hop) to align click tracks and tap in synchrony with genre-specific and genre-neutral sound stimuli to determine the perceptual center (“P-center”) and variability (“beat bin”) for each group of experts. We had three stimulus categories – Organic, Electronic, and Neutral sounds – each of which had a 2 × 2 design of the acoustic factors Attack (fast/slow) and Duration (short/long). We found significant effects of Genre expertise, and a significant interaction for both P-center and P-center variability: folk and jazz musicians synchronize to sounds typical of folk and jazz in a different manner than the EDM/hip-hop producers. The results show that expertise in a specific musical genre affects our low-level perceptions of sounds as well as their affordance(s) for joint action/synchronization. The study provides new insights into the effects of active long-term musical enculturation and skill acquisition on basic sensorimotor synchronization and timing perception, shedding light on the important question of how nature and nurture intersect in the development of our perceptual systems.

False memories formation is increased in individuals with insomnia.

SummaryPrevious studies suggest that sleep can influence false memories formation. Specifically, acute sleep loss has been shown to promote false memories production by impairing memory retrieval at subsequent testing. Surprisingly, the relationship between sleep and false memories has only been investigated in healthy subjects but not in individuals with insomnia, whose sleep is objectively impaired compared to healthy subjects. Indeed, this population shows several cognitive impairments involving prefrontal functioning that could affect source monitoring processes and contribute to false memories generation. Moreover, it has been previously reported that subjects with insomnia differentially process sleep‐related versus neutral stimuli. Therefore, the aim of the present study was to compare false memories production between individuals with insomnia symptoms and good sleepers, and to evaluate the possible influence of stimulus category (neutral versus sleep‐related) in the two groups. The results show that false memories are globally increased in participants reporting insomnia symptoms compared to good sleepers. A reduction in source monitoring ability was also observed in the former group, suggesting that an impairment of this executive function could be especially involved in false memories formation. Moreover, our data seem to confirm that false memories production in individuals with insomnia symptoms appears significantly modulated by stimulus category.

Individual differences in perception of the speech-to-song illusion are linked to musical aptitude but not musical training.

In the speech-to-song illusion, certain spoken phrases are perceived as sung after repetition. One possible explanation for this increase in musicality is that, as phrases are repeated, lexical activation dies off, enabling listeners to focus on the melodic and rhythmic characteristics of stimuli and assess them for the presence of musical structure. Here we tested the idea that perception of the illusion requires implicit assessment of melodic and rhythmic structure by presenting individuals with phrases that tend to be perceived as song when repeated, as well as phrases that tend to continue to be perceived as speech when repeated, measuring the strength of the illusion as the rating difference between these two stimulus categories after repetition. Illusion strength varied widely and stably between listeners, with large individual differences and high split-half reliability, suggesting that not all listeners are equally able to detect musical structure in speech. Although variability in illusion strength was unrelated to degree of musical training, participants who perceived the illusion more strongly were proficient in several musical skills, including beat perception, tonality perception, and selective attention to pitch. These findings support models of the speech-to-song illusion in which experience of the illusion is based on detection of musical characteristics latent in spoken phrases. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Breast Tissue Density Influences Tumor Malignancy Perception and Decisions in Mammography

High density breast tissue has been found to reduce radiologists’ accuracy in detecting and classifying mammogram abnormalities. The current research examines the perceptual and decisional components that underlie diagnostic classification (independent of detection) in a sample of novices. Mammograms were varied along two dimensions: Breast tissue density (low/high) and the nature of an identified mass (benign/malignant). In two experiments, participants learned to classify images into 4 categories created by factorial combination of these dimensions. In low density tissue, accuracy was higher for benign than for malignant masses. Surprisingly, and in contrast to the mammography literature, accuracy for malignant masses was higher in high-density than in low-density tissue. Cognitive modeling based in general recognition theory (GRT) indicated that low-density/benign category accuracy was largely due to high perceptual discriminability for that category. The high accuracy level for malignant masses in high density tissue was accounted for by decision bound slopes that favored the “malignant” response for items in the high-density malignant category. Because GRT can provide insight into perceptual and decisional determinants of observed classification accuracy, as well as individual-difference level parameters about attention allocation, GRT may be a means to obtain a more detailed understanding of diagnostic classification of complex naturalistic stimuli.

Combining Statistical Analysis and Machine Learning for EEG Scalp Topograms Classification.

Incorporating brain-computer interfaces (BCIs) into daily life requires reducing the reliance of decoding algorithms on the calibration or enabling calibration with the minimal burden on the user. A potential solution could be a pre-trained decoder demonstrating a reasonable accuracy on the naive operators. Addressing this issue, we considered ambiguous stimuli classification tasks and trained an artificial neural network to classify brain responses to the stimuli of low and high ambiguity. We built a pre-trained classifier utilizing time-frequency features corresponding to the fundamental neurophysiological processes shared between subjects. To extract these features, we statistically contrasted electroencephalographic (EEG) spectral power between the classes in the representative group of subjects. As a result, the pre-trained classifier achieved 74% accuracy on the data of newly recruited subjects. Analysis of the literature suggested that a pre-trained classifier could help naive users to start using BCI bypassing training and further increased accuracy during the feedback session. Thus, our results contribute to using BCI during paralysis or limb amputation when there is no explicit user-generated kinematic output to properly train a decoder. In machine learning, our approach may facilitate the development of transfer learning (TL) methods for addressing the cross-subject problem. It allows extracting the interpretable feature subspace from the source data (the representative group of subjects) related to the target data (a naive user), preventing the negative transfer in the cross-subject tasks.

Age-related declines in neural distinctiveness correlate across brain areas and result from both decreased reliability and increased confusability

ABSTRACT According to the neural dedifferentiation hypothesis, age-related reductions in the distinctiveness of neural representations contribute to sensory, cognitive, and motor declines associated with aging: neural activity associated with different stimulus categories becomes more confusable with age and behavioral performance suffers as a result. Initial studies investigated age-related dedifferentiation in the visual cortex, but subsequent research has revealed declines in other brain regions, suggesting that dedifferentiation may be a general feature of the aging brain. In the present study, we used functional magnetic resonance imaging to investigate age-related dedifferentiation in the visual, auditory, and motor cortices. Participants were 58 young adults and 79 older adults. The similarity of activation patterns across different blocks of the same category was calculated (within-category correlation, a measure of reliability) as was the similarity of activation patterns elicited by different categories (between-category correlations, a measure of confusability). Neural distinctiveness was defined as the difference between the mean within- and between-category similarity. We found age-related reductions in neural distinctiveness in the visual, auditory, and motor cortices, which were driven by both decreases in within-category similarity and increases in between-category similarity. There were significant positive cross-region correlations between neural distinctiveness in different regions. These correlations were driven by within-category similarities, a finding that indicates that declines in the reliability of neural activity appear to occur in tandem across the brain. These findings suggest that the changes in neural distinctiveness that occur in healthy aging result from changes in both the reliability and confusability of patterns of neural activity.