Stimulus Objects Research Articles

Направленность внимания у детей с РАС

The special way of understanding the world and the brain mechanisms of cognitive impairment in children with autism spectrum disorders (ASD) are becoming the core topics in the autism research. The article presents a study of the general characteristics of attention in children of primary school age with ASD using instruments aimed at detecting impairments of attention parameters: Schulte Tables, Go/No Go Task, Kraepelin’s Arithmetic Test, Stroop Test used to study the focus of attention in the context of the interference of verbal and object stimuli. Results of study of attention in children with ASD seemed to be ambivalent. Children with ASD are successful in performing the Schulte Tables; on the contrary, the Go/No Go Task shows the difficulties of performing the tasks and inhibition of dominant response. Different degrees of unstable focus of attention in tasks on visual perception also shown. The features of focusing attention in conditions of interference require further research. Preliminary results showed that the focus of attention in younger schoolchildren with ASD is associated with a preference for verbal rather than object characteristics of visual stimuli.

El objeto de la psicología como ciencia: relación sin “cuerpo-substancia”

The subject matter of psychology as a science is examined from the viewpoint of the phenomenology of ‘mental’ expressions in ordinary language practices. Different historical attempts to provide body and substance to the subject matter of psychology are revisited: Descartes, Brentano, McDougall, and Watson. The overcoming of this erroneus trend by the field logic proposed by J.R. Kantor, conceiving psychology as relation between an individual and a stimulus object, is examined. Implications of this formulation are discussed in regard to the widening and extensión of the domain of psychoogical phenomena to the animal kingdom, the relationships of psychology with ecobiology and historical social science conceiving psychology as a coextensive science, the concept of ‘individual’ as an outcome of the processes of speciation or socialization, and the density occupied by psychological behavior in the continua of biological and social behaviors.

Transcranial alternating current stimulation (tACS) at 40 Hz enhances face and object perception

Neurophysiological evidence suggests that face and object recognition relies on the coordinated activity of neural populations (i.e., neural oscillations) in the gamma-band (>30 Hz) range over the occipito-temporal cortex. To test the causal effect of gamma-band oscillations on face and object perception we applied transcranial Alternating Current Stimulation (tACS) in healthy volunteers (N = 60). In this single-blind, sham-controlled study, we examined whether the administration of offline tACS at gamma-frequency (40 Hz) over the right occipital cortex enhances performance of perception and memory of face and object stimuli. We hypothesized that gamma tACS would enhance the perception of both categories of visual stimuli. Results, in line with our hypothesis, show that 40 Hz tACS enhanced both face and object perception. This effect is process-specific (i.e., it does not affect memory), frequency-specific (i.e., stimulation at 5 Hz did not cause any behavioural change), and site-specific (i.e., stimulation of the sensory-motor cortex did not affect performance). Our findings show that high-frequency tACS modulates human visual perception, and it is in line with neurophysiological studies showing that the perception of visual stimuli (i.e., faces and objects) is mediated by oscillations in the gamma-band range. Furthermore, this study adds insight about the design of effective neuromodulation protocols that might have implications for interventions in clinical settings.

Discrimination Thresholds for Passive Tactile Volume Perception by Fingertips.

Haptic object perception is still poorly understood up to now. This study investigated the ability of human fingers to discriminate the volume of objects by passive touch. Experiments measured the discrimination threshold of volume using three tasks: passive tactile volume perception, passive tactile area perception, and active tactile volume perception. In each trial, we utilized two plastic cubes to successively stimulate the fingers, and participants were instructed to make comparisons between the stimulus objects’ volume and area. Results showed that there was no significant difference in the discrimination thresholds of tactile volume perception between passive touch and active touch, whereas significant differences in the discrimination thresholds between fingertips, such as the thumb versus the pinky finger. In passive touch, the discrimination thresholds of volume perception were larger than that with surface area perception. We found that the discrimination of the volume of objects is more difficult than the discrimination of the area of the objects.

Attention is a prerequisite for the neural effects of perceptual predictions

Perception is often guided by predictions that we derive from previous experience. However, the automaticity of these perceptual predictions remains a topic of discussion. We and others have previously shown that neural responses to expected compared to unexpected object stimuli are suppressed throughout several cortical areas, including major parts of the ventral visual stream. In the current study, we examined whether these effects require attention to the predictable stimuli. Using fMRI in a sample (n=34) of healthy volunteers, we find that attention to the object stimuli is a prerequisite for the suppression of neural responses by expectation. Moreover, we show that while attention to the object stimulus is required for expectation suppression, the predictive relationship itself does not need to be task-relevant or attended. Our results indicate that predictions derived from previous experience do not always impact sensory processing, but rather emerge selectively when the predictable stimuli are attended.

The role of language in novel task learning

The ability to rapidly acquire novel cognitive skills is a hallmark of human cognition. Theories of skill acquisition assume that this process is reliant on language, but to date this assertion has not been conclusively supported by empirical evidence. In two experiments participants (total N = 68) were required to learn, by trial-and-error, the correct response to sets of five object stimuli. To investigate the contribution of language to this process, participants performed a verbal (articulatory suppression), a non-verbal (foot tapping), or no distractor task during the first or second half of each task. In both experiments, articulatory suppression resulted in increased error rates (compared to foot tapping), but only during the first (and not the second) half of each task. These results constitute the first convincing evidence for the diminishing role of language in novel task learning and are discussed in relation to theories of skill acquisition.

Statistical learning attenuates visual activity only for attended stimuli.

Perception and behavior can be guided by predictions, which are often based on learned statistical regularities. Neural responses to expected stimuli are frequently found to be attenuated after statistical learning. However, whether this sensory attenuation following statistical learning occurs automatically or depends on attention remains unknown. In the present fMRI study, we exposed human volunteers to sequentially presented object stimuli, in which the first object predicted the identity of the second object. We observed a reliable attenuation of neural activity for expected compared to unexpected stimuli in the ventral visual stream. Crucially, this sensory attenuation was only apparent when stimuli were attended, and vanished when attention was directed away from the predictable objects. These results put important constraints on neurocomputational theories that cast perception as a process of probabilistic integration of prior knowledge and sensory information.

Men Scare Me More: Gender Differences in Social Fear Conditioning in Virtual Reality.

Women nearly twice as often develop social anxiety disorder (SAD) compared to men. The reason for this difference is still being debated. The present study investigates gender differences and the effect of male versus female agents in low (LSA) and high socially anxious (HSA) participants regarding the acquisition and extinction of social fear in virtual reality (VR). In a social fear conditioning (SFC) paradigm, 60 participants actively approached several agents, some of which were paired with an aversive unconditioned stimulus (US) consisting of a verbal rejection and spitting simulated by an aversive air blast (CS+), or without an US (CS−). Primary outcome variables were defined for each of the 4 levels of emotional reactions including experience (fear ratings), psychophysiology (fear-potentiated startle), behavior (avoidance), and cognition (recognition task). Secondary outcome variables were personality traits, contingency ratings, heart rate (HR), and skin conductance response (SCR). As hypothesized, fear ratings for CS+ increased significantly during acquisition and the differentiation between CS+ and CS− vanished during extinction. Additionally, women reported higher fear compared to men. Furthermore, a clear difference in the fear-potentiated startle response between male CS+ and CS− at the end of acquisition indicates successful SFC to male agents in both groups. Concerning behavior, results exhibited successful SFC in both groups and a general larger distance to agents in HSA than LSA participants. Furthermore, HSA women maintained a larger distance to male compared to female agents. No such differences were found for HSA men. Regarding recognition, participants responded with higher sensitivity to agent than object stimuli, suggesting a higher ability to distinguish the target from the distractor for social cues, which were on focus during SFC. Regarding the secondary physiological outcome variables, we detected an activation in HR response during acquisition, but there were no differences between stimuli or groups. Moreover, we observed a gender but no CS+/CS− differences in SCR. SFC was successfully induced and extinguished according to the primary outcome variables. VR is an interesting tool to measure emotional learning processes on different outcome levels with enhanced ecological validity. Future research should further investigate social fear learning mechanisms for developing more efficient treatments of SAD.

Comorbidities of early-onset temporal epilepsy: Cognitive, social, emotional, and morphologic dimensions

Epilepsy, the most common neurologic disorder in childhood, is associated with a subset of psychiatric dysfunctions, including cognitive deficits, and alterations in emotionality (e.g., anxiety and depression) and social functioning. In the present study, we evaluated an integrative set of behavioral responses, including cognitive/socio-cognitive and emotional dimensions, using a number of behavioral paradigms in the LiCl/pilocarpine model of status epilepticus (SE) in rats. The aims of the study were to examine whether SE affects: 1) non-associative learning (habituation of exploratory behavior); 2) investigatory response to an indifferent stimulus object; 3) sociability/social novelty preference; 4) social recognition or discrimination; and 4) short- and long-term memory in the Morris water maze (MWM). Finally, we investigated the morphology of key brain structures involved in the examined behavioral dysfunctions. SE did not affect habituation to an open-field arena in juvenile (P25), adolescent (P32), or adult (P80) rats. SE rats spent less time in the central part of the arena. SE adolescent rats (P32) displayed a higher number of rearings with a shorter duration. SE rats displayed a markedly attenuated investigatory response to an indifferent stimulus object. SE rats in all age groups demonstrated pronounced deficits in sociability and the preference for social novelty. In addition, SE rats spent a reduced amount of time investigating a juvenile rat upon first exposure. After 30 min re-exposure together with an additional, novel juvenile, the SE rats spent equal time investigating both juveniles. In the MWM task, acquisition was unimpaired but there was a deficit in delayed memory retention after 10 days. SE did not affect cognitive flexibility expressed by reversal learning. Together, these findings suggest that early-life SE leads to alterations in emotional/anxiety-related behavior and affects sociability/preference for social novelty and social discrimination. Early-life SE did not alter acquisition of spatial learning, but it impaired delayed retention. Using Fluoro Jade B staining performed 24 h after SE revealed apparent neurodegeneration in the dorsal hippocampus, mediodorsal thalamic nucleus and medial amygdala, brain areas that are critically involved in network underlying emotional behavior and cognitive functions.

The Recognition of Solid Object Shape: The Importance of Inhomogeneity.

A single experiment evaluated the haptic-visual cross-modal matching of solid object shape. One set of randomly shaped artificial objects was used (sinusoidally modulated spheres, SMS) as well as two sets of naturally shaped objects (bell peppers, Capsicum annuum and sweet potatoes, Ipomoea batatas). A total of 66 adults participated in the study. The participants’ task was to haptically explore a single object on any particular trial and subsequently indicate which of 12 simultaneously visible objects possessed the same shape. The participants’ performance for the natural objects was 60.9 and 78.7 percent correct for the bell peppers and sweet potatoes, respectively. The analogous performance for the SMS objects, while better than chance, was far worse (18.6 percent correct). All of these types of stimulus objects possess a rich geometrical structure (e.g., they all possess multiple elliptic, hyperbolic, and parabolic surface regions). Nevertheless, these three types of stimulus objects are perceived differently: Individual members of sweet potatoes and bell peppers are largely identifiable to human participants, while the individual SMS objects are not. Analyses of differential geometry indicate that these natural objects (e.g., bell peppers and sweet potatoes) possess heterogeneous spatial configurations of distinctly curved surface regions, and this heterogeneity is lacking in SMS objects. The current results therefore suggest that increases in surface structure heterogeneity facilitate human object recognition.

Methods for Presenting Real-world Objects Under Controlled Laboratory Conditions.

Our knowledge of human object vision is based almost exclusively on studies in which the stimuli are presented in the form of computerized two-dimensional (2-D) images. In everyday life, however, humans interact predominantly with real-world solid objects, not images. Currently, we know very little about whether images of objects trigger similar behavioral or neural processes as do real-world exemplars. Here, we present methods for bringing the real-world into the laboratory. We detail methods for presenting rich, ecologically-valid real-world stimuli under tightly-controlled viewing conditions. We describe how to match closely the visual appearance of real objects and their images, as well as novel apparatus and protocols that can be used to present real objects and computerized images on successively interleaved trials. We use a decision-making paradigm as a case example in which we compare willingness-to-pay (WTP) for real snack foods versus 2-D images of the same items. We show that WTP increases by 6.6% for food items displayed as real objects versus high-resolution 2-D coloredimages of the same foods -suggesting that real foods are perceived as being more valuable than their images. Although presenting real object stimuli under controlled conditions presents several practical challenges for the experimenter, this approach will fundamentally expand our understanding of the cognitive and neural processes that underlie naturalistic vision.

Extended categorization of conjunction object stimuli decreases the latency of attentional feature selection and recruits orthography-linked ERPs

The role of attention in driving perceptual expertise effects is controversial. The current study addressed the effect of training on ERP components related to and independent of attentional feature selection. Participants learned to categorize cartoon animals over six training sessions (8,800 trials) after which ERPs were recorded during a target detection task performed on trained and untrained stimulus sets. The onset of the selection negativity, an ERP component indexing attentional modulation, was about 60 msec earlier for trained than untrained stimuli. Trained stimuli also elicited centro-parietal N200 and N320 components that were insensitive to attentional feature selection. The scalp distribution and timecourse of these components were better matched by studies of orthography than object expertise. Source localization using eLORETA suggested that the strongest neural sources of the selection negativity were in right ventral temporal cortex whereas the strongest sources of the N200/N320 components were in left ventral temporal cortex, again consistent with the hypothesis that training recruited orthography related areas. Overall, training altered neural processes related to attentional selection, but also affected neural processes that were independent of feature selection.

Developmental changes in orienting towards faces: A behavioral and eye-tracking study

Previous studies show that newborn infants and adults orient their attention preferentially toward human faces. However, the developmental changes of visual attention captured by face stimuli remain unclear, especially when an explicit top-down process is involved. We capitalized on a visual search paradigm to assess how the relative strength of visual attention captured by a non-target face stimulus and explicit attentional control on a target stimulus evolve as search progresses and how this process changes during development. Ninety children aged 5–14 years searched for a target within an array of distractors, which occasionally contained an upright face. To assess the precise picture of developmental changes, we measured: (1) manual responses, such as reaction time and accuracy; and (2) eye movements such as the location of the first fixation, which reflect the attentional profile at the initial stage, and looking times, which reflect the attentional profile at the later period of searching. Both reaction time and accuracy were affected by the presence of the target-unrelated face, though the interference effect was observed consistently across ages. However, developmental changes were captured by the first fixation proportion, suggesting that initial attention was preferentially directed towards the target-unrelated face before 6.9 years of age. Furthermore, prior to 12.8 years of age, the first fixation towards face stimuli was significantly more frequent than for object stimuli. In contrast, the looking time proportion for the face stimuli was significantly higher than that for the objects across all ages. These findings suggest that developmental changes do not influence the later search periods during a trial, but that they influence the initial orienting indexed by the first fixation. Moreover, the manual responses are tightly linked to eye movement behaviors.

THE SELF AS AN ANCHOR: HOW DO HUMAN ASCRİBE VALUE TO THİNGS

According to the norm theory of Kahneman and Miller, when people evaluate an object, they often think about other objects in the same category, and compare the stimulus object to the anchor (Hsee, 1998, 109). However, people would intrinsically ascribe value to things (Hood & Bloom, 2008) without using an explicit anchor. We argue that instrumental value is embedded in the intrinsic one and therefore intrinsic valuation is active for any evaluation of the individual. In the study, the existence of intrinsic value was tested by using the meditative state of mind as a tool and author found three omnipresent phenomena that affect the assigned value of things: a) Just after a high level of meditative state, participants distinctly assigned lower values to images relative to their non-meditative peers. b) Participants assigned significantly higher values to more complex images only when they focused on these images for a while. c) When participants made instant valuation, while the complexity of images rising, the values assigned took in the form of a U-curve. These situationalities has been integrated and resolved on a theoretical ground..

Do as I say - or as I do?! How 18- and 24-month-olds integrate words and actions to infer intentions in situations of match or mismatch

Infants use behavioral and verbal cues to infer another person’s action intention. However, it is still unclear how infants integrate these often co-occurring cues depending on the cues’ coherence (i.e., the degree to which the cues provide coherent information about another’s intention). This study investigated how 18- and 24-month-olds’ (N = 88 per age group) action selection was influenced by varying the coherence of a model’s verbal and behavioral cues. Using a between-subjects design, infants received six trials with different stimulus objects. In the conditions Congruent, Incongruent, and Failed-attempt, the model uttered a telic verb particle that was followed by a matching or contradicting goal-directed action demonstration, or by a non goal-directed slipping motion, respectively. In the condition Pseudo-word, a nonsense word was combined with a goal-directed action demonstration. Infants’ action selection indicated an adherence to the verbal cue in Congruent, Incongruent, and Failed-attempt, and this was stronger in 24- than 18-month-olds. Additionally, in Incongruent and Failed-attempt, patterns of cue integration across the six trials varied in the two age groups. Regarding the behavioral cue, infants in Congruent and Pseudo-word preferentially followed this cue in both age groups, which also suggested a rather unspecific effect of the verbal cue in Congruent. Relatively longer first action-latencies in Incongruent and Failed-attempt implied that these types of coherence elicited higher cognitive demands than in Congruent and Pseudo-word. Results are discussed in light of infants’ flexibility in using social cues, depending on the cue’s coherence and on age-related social-cognitive differences.

Human frontoparietal cortex represents behaviorally relevant target status based on abstract object features.

Searching for items that are useful given current goals, or "target" recognition, requires observers to flexibly attend to certain object properties at the expense of others. This could involve focusing on the identity of an object while ignoring identity-preserving transformations such as changes in viewpoint or focusing on its current viewpoint while ignoring its identity. To effectively filter out variation due to the irrelevant dimension, performing either type of task is likely to require high-level, abstract search templates. Past work has found target recognition signals in areas of ventral visual cortex and in subregions of parietal and frontal cortex. However, target status in these tasks is typically associated with the identity of an object, rather than identity-orthogonal properties such as object viewpoint. In this study, we used a task that required subjects to identify novel object stimuli as targets according to either identity or viewpoint, each of which was not predictable from low-level properties such as shape. We performed functional MRI in human subjects of both sexes and measured the strength of target-match signals in areas of visual, parietal, and frontal cortex. Our multivariate analyses suggest that the multiple-demand (MD) network, including subregions of parietal and frontal cortex, encodes information about an object's status as a target in the relevant dimension only, across changes in the irrelevant dimension. Furthermore, there was more target-related information in MD regions on correct compared with incorrect trials, suggesting a strong link between MD target signals and behavior. NEW & NOTEWORTHY Real-world target detection tasks, such as searching for a car in a crowded parking lot, require both flexibility and abstraction. We investigated the neural basis of these abilities using a task that required invariant representations of either object identity or viewpoint. Multivariate decoding analyses of our whole brain functional MRI data reveal that invariant target representations are most pronounced in frontal and parietal regions, and the strength of these representations is associated with behavioral performance.

Anodal tDCS and High-Frequency tRNS Targeting the Occipitotemporal Cortex Do Not Always Enhance Face Perception.

There has been increasing interest in the utility of transcranial electrical stimulation as a tool to enhance cognitive abilities. In the domain of face perception, enhancements have been reported for both transcranial direct current stimulation (tDCS) and high-frequency transcranial random noise stimulation (tRNS) targeting the occipitotemporal cortex. In a series of two experiments, we attempted to replicate these findings for face identity perception, and extend on previous studies, to determine if similar enhancements are also observed for object and facial expression perception. In Experiment 1, using a single blind, between-subjects design in healthy volunteers (N = 53), we examined whether anodal tDCS over the occipitotemporal cortex enhanced performance on tasks involving perception of face identity, facial expression, and object stimuli, when compared to sham stimulation. We failed to replicate previous findings of enhanced performance on face and object perception, nor extend findings to facial expression perception. In Experiment 2, using a single blind, between-subjects design (N = 39), we examined the effect of high-frequency tRNS over the occipitotemporal cortex using the same three tasks employed in Experiment 1. We failed to replicate previous findings of enhanced face perception following high-frequency tRNS over the occipitotemporal cortex, relative to sham stimulation (although we used different stimulation parameters to that employed in a previous study). We also found no evidence of enhanced facial expression and object perception following high-frequency tRNS. The findings align with a growing body of studies that have failed to replicate previously reported enhancements following administration of tDCS and hint for different efficacy of, on first sight, related stimulation protocols. Future studies should explore the foundation of these differential effects in greater detail.

Sub-millimeter fMRI Reveals Columnar Organization in Macaque Parietal Cortex

Sub-millimeter fMRI Reveals Columnar Organization in Macaque Parietal Cortex

Haptic Distance Ratio Estimation: The Geometry of Space Within the Hands.

In the current study of haptic distance perception, 20 younger (median age: 22 years) and 20 older adults (median age: 72 years) used active touch to estimate distance ratios(one length relative to another). Nine tactile stimuli were created from wooden dowels; each consisted of two perpendicular dowels. The stimulus distance ratios ranged from 1.0 to 5.0. Each participant used both hands (without vision) to actively explore (30 s) a single stimulus object on every trial. The task was to numerically estimate the distance ratio. Overall, the participants’ judgments were precise; the overall magnitude of the Pearson r correlation coefficient was 0.943 and did not differ for younger and older adults. While the participants’ judgments were precise, they were not completely accurate: The average slope (of the relationship between actual and judged distance ratios) for all participants was significantly greater than 1.0 (1.15). Surprisingly, differences in manual dexterity had no apparent effect on distance ratio estimates. Older adults apparently retain an excellent ability to perceive distances using their sense of touch. Our results also demonstrate that the geometry of haptic space (at the scale of the hand) is approximately Euclidean in nature (and certainly not merely topological, projective, or affine).

Conscious awareness is required for the perceptual discrimination of threatening animal stimuli: A visual masking and continuous flash suppression study.

We investigated if the subliminal processing of threatening animal (snakes and spiders) and neutral object (cars and houses) stimuli can influence the discrimination of a subsequent visible stimulus. The prime and target pair were either identical, of the same category but with different physical features, or different in category and physical features. In two experiments, participants discriminated the basic level category (e.g. snake vs. spider) of a visible target stimulus that had been preceded by a visible or perceptually invisible prime stimulus. One experiment used visual masking to render prime stimuli perceptually invisible and the other used continuous flash suppression (CFS). Priming effects were demonstrated in both experiments when the prime was visible but not when the prime was rendered perceptually invisible. These findings demonstrate that conscious awareness could be required in the perceptual discrimination of threatening animal and neutral object images at their specific basic level category.