Aspects Of Stimuli Research Articles

The Role of Musical Experience in Hemispheric Lateralization of Global and Local Auditory Processing.

The global precedence effect is a phenomenon in which global aspects of visual and auditory stimuli are processed before local aspects. Individuals with musical experience perform better on all aspects of auditory tasks compared with individuals with less musical experience. The hemispheric lateralization of this auditory processing is less well-defined. The present study aimed to replicate the global precedence effect with auditory stimuli and to explore the lateralization of global and local auditory processing in individuals with differing levels of musical experience. A total of 38 college students completed an auditory-directed attention task while electroencephalography was recorded. Individuals with low musical experience responded significantly faster and more accurately in global trials than in local trials regardless of condition, and significantly faster and more accurately when pitches traveled in the same direction (compatible condition) than when pitches traveled in two different directions (incompatible condition) consistent with a global precedence effect. In contrast, individuals with high musical experience showed less of a global precedence effect with regards to accuracy, but not in terms of reaction time, suggesting an increased ability to overcome global bias. Further, a difference in P300 latency between hemispheres was observed. These findings provide a preliminary neurological framework for auditory processing of individuals with differing degrees of musical experience.

Task set induces dynamic reallocation of resources in visual short-term memory.

Successful interaction with the environment requires the ability to flexibly allocate resources to different locations in the visual field. Recent evidence suggests that visual short-term memory (VSTM) resources are distributed asymmetrically across the visual field based upon task demands. Here, we propose that context, rather than the stimulus itself, determines asymmetrical distribution of VSTM resources. To test whether context modulates the reallocation of resources to the right visual field, task set, defined by memory-load, was manipulated to influence visual short-term memory performance. Performance was measured for single-feature objects embedded within predominantly single- or two-feature memory blocks. Therefore, context was varied to determine whether task set directly predicts changes in visual field biases. In accord with the dynamic reallocation of resources hypothesis, task set, rather than aspects of the physical stimulus, drove improvements in performance in the right- visual field. Our results show, for the first time, that preparation for upcoming memory demands directly determines how resources are allocated across the visual field.

A functional near-infrared spectroscopy study of the effects of configural properties on sustained attention

Forty-five participants performed a vigilance task during which they were required to respond to a critical signal at a local feature level, while the global display was altered between groups (either a circle, a circle broken apart and reversed, or a reconnected figure). The shape in two of the groups formed a configurative whole (the circle and reconnected conditions), while the remaining shape had no complete global element (broken circle). Performance matched the results found in the previous experiments using this stimulus set, where a configural superiority effect was found to influence accuracy over time. Physiological data, measured using functional near-infrared spectroscopy, revealed elevated activation in the right pre-frontal cortex compared to the left pre-frontal cortex during the task. Additionally, bilateral activation was found in the conditions that formed configurative wholes, while hemispheric differences over time were found in the condition that did not. These findings suggest that configural aspects of stimuli may explain why non-typical laterality effects have been found in similar research.

Amygdala-Cortical Connectivity: Associations with Anxiety, Development, and Threat.

Amygdala-prefrontal cortex (PFC) functional connectivity may be influenced by anxiety and development. A prior study on anxiety found age-specific dysfunction in the ventromedial PFC (vmPFC), but not amygdala, associated with threat-safety discrimination during extinction recall (Britton etal.). However, translational research suggests that amygdala-PFC circuitry mediates responses following learned extinction. Anxiety-related perturbations may emerge in functional connectivity within this circuit during extinction recall tasks. The current report uses data from the prior study to examine how anxiety and development relate to task-dependent amygdala-PFC connectivity. Eighty-two subjects (14 anxious youths, 15 anxious adults, 25 healthy youths, 28 healthy adults) completed an extinction recall task, which directed attention to different aspects of stimuli. Generalized psychophysiological interaction analysis tested whether task-dependent functional connectivity with anatomically defined amygdala seed regions differed across anxiety and age groups. Whole-brain analyses showed significant interactions of anxiety, age, and attention task (i.e., threat appraisal, explicit threat memory, physical discrimination) on left amygdala functional connectivity with the vmPFC and ventral anterior cingulate cortex (Talairach XYZ coordinates: -16, 31, -6 and 1, 36, -4). During threat appraisal and explicit threat memory (vs. physical discrimination), anxious youth showed more negative amygdala-PFC coupling, whereas anxious adults showed more positive coupling. In the context of extinction recall, anxious youths and adults manifested opposite directions of amygdala-vmPFC coupling, specifically when appraising and explicitly remembering previously learned threat. Future research on anxiety should consider associations of both development and attention to threat with functional connectivity perturbations.

HiTEC: a connectionist model of the interaction between perception and action planning

Increasing evidence suggests that perception and action planning do not represent separable stages of a unidirectional processing sequence, but rather emerging properties of highly interactive processes. To capture these characteristics of the human cognitive system, we have developed a connectionist model of the interaction between perception and action planning: HiTEC, based on the Theory of Event Coding (Hommel et al. in Behav Brain Sci 24:849–937, 2001). The model is characterized by representations at multiple levels and by shared representations and processes. It complements available models of stimulus–response translation by providing a rationale for (1) how situation-specific meanings of motor actions emerge, (2) how and why some aspects of stimulus–response translation occur automatically and (3) how task demands modulate sensorimotor processing. The model is demonstrated to provide a unitary account and simulation of a number of key findings with multiple experimental paradigms on the interaction between perception and action such as the Simon effect, its inversion (Hommel in Psychol Res 55:270–279, 1993), and action–effect learning.

LCD Monitors as an Alternative for Precision Demanding Visual Psychophysical Experiments.

Precise timing and presentation of stimuli is critical in vision research, still, the limiting factor in successful recognition is often the monitor itself that is used to present the stimuli. The most widespread method is the use of monitors controlled by personal computers. Traditionally, most experiments used cathode-ray tubes but they are more and more difficult to access, and instead, liquid-crystal displays are getting more and more popular. The two types have fundamentally different working principles and limitations in displaying the stimulus.In our experiments, the temporal precision of the stimulus presentation was in focus. We investigated whether liquid-crystal displays, which are not considered to be fit to display fast successive stimuli, can represent an alternative choice for cathode-ray tubes. We used the double flash and the flicker illusion to compare the technical capabilities of the two monitor types. These illusions not only do require a precise timing but also a very short exposure to the stimuli. At the same time, the interstimulus interval is also of extreme importance. In addition, these illusions require peripheral stimulation of the retina, which is more sensitive to the temporal aspects of the visual stimulus. On the basis of previous studies and our own psychophysical results, we suggest that liquid-crystal displays might be a good alternative for precise, frame-to-frame stimulus presentation even if parts of the stimuli are projected on the peripheral retina.

Early averted gaze processing in the right Fusiform Gyrus: An EEG source imaging study

Humans are able to categorize face properties with impressively short latencies. Nevertheless, the latency at which gaze recognition occurs is still a matter of debate. Through spatio-temporal analysis of high-density event-related potentials (ERP), we investigated the brain activity underlying the ability to spontaneously and quickly process gaze. We presented neutral faces with direct and averted gaze in a matching picture paradigm, where subjects had to detect repetition of identical faces and gaze was implicitly manipulated.The results indicate that faces with averted gaze were better discriminated than faces with direct gaze, and evoked stronger P100 amplitudes localized to the right fusiform gyrus. In contrast, direct gaze induced stronger activation in the orbital frontal gyrus at this latency. Later in time, at the beginning of the N170 component, direct gaze induced changes in scalp topography with a stronger activation in the right medial temporal gyrus. The location of these differential activations of direct vs. averted gaze further support the view that faces with averted gaze are perceived as less rewarding than faces with direct gaze. We additionally found differential ERP responses between repeated and novel faces as early as 50ms, thereby replicating earlier studies of very fast detection of mnestic aspects of stimuli. Together, these results suggest an early dissociation between implicit gaze detection and explicit identity processing.

Selective attention in dairy cattle

In a replication of Reynolds (1961), two cows learned to discriminate between compound stimuli in a forced choice procedure where pushing through a one-way gate marked with a red cross (S+) gave access to food. Pushing through a one-way gate marked with a yellow triangle (S−) gave no access to food. To investigate whether shape or colour was controlling behaviour, probe tests varied either the shape or the colour of the stimuli (e.g., a red vs. a yellow cross, and a red cross vs. a red triangle). Results suggested control by colour rather than shape, as the gate marked with the red stimulus was chosen more than the gate marked with the yellow stimulus regardless of stimulus shape, and when two shapes of the same colour (either red or yellow) were presented, cows chose both equally. Further probe tests with painted red, white, and yellow stimuli showed that the cows had learned to avoid yellow rather than to approach red, suggesting discriminative behaviour was controlled by the colour of the negative stimulus and not by either aspect of the positive stimulus. It is not clear why the negative stimulus was more salient, but it may reflect a tendency for cows to learn to avoid farm handling practices which involve mainly negative stimuli.

Parahippocampal Cortex Processes the Nonspatial Context of an Event.

Parahippocampal cortex (PHc) is known to process spatial information, both in perceptual and episodic memory studies. However, recent theories propose an expanded role for PHc in processing context information in general, whether spatial or nonspatial. The current study used a source memory paradigm to investigate encoding and retrieval of nonspatial context information. Human participants were asked to judge lexical aspects of word stimuli and to retrieve those judgments during a later memory test. Anterior PHc showed significantly greater activation for items associated with correct source judgments than items associated with incorrect source judgments during both encoding and retrieval phases. These findings suggest that the role of PHc in episodic memory cannot be limited to spatial information.

Young children’s appreciation and production of verbal and visual humor

AbstractThis study aimed to investigate young children’s ability to appreciate and produce humor. Specifically the research questions were: 1. What aspects of a humorous visual stimulus do children of the ages 4–7 years appreciate and why? 2. What are the differences, if any, in producing a humorous story and a drawing? Are these related to creativity variables? 3. How are children’s appreciation and production of visual humor related to the Theory of the Absurd and the Empowerment theory (Loizou 2005, Infant humor: The theory of the absurd and the empowerment theory.

High-resolution Quantification of Odor-guided Behavior in Drosophila melanogaster Using the Flywalk Paradigm.

In their natural environment, insects such as the vinegar fly Drosophila melanogaster are bombarded with a huge amount of chemically distinct odorants. To complicate matters even further, the odors detected by the insect nervous system usually are not single compounds but mixtures whose composition and concentration ratios vary. This leads to an almost infinite amount of different olfactory stimuli which have to be evaluated by the nervous system. To understand which aspects of an odor stimulus determine its evaluation by the fly, it is therefore desirable to efficiently examine odor-guided behavior towards many odorants and odor mixtures. To directly correlate behavior to neuronal activity, behavior should be quantified in a comparable time frame and under identical stimulus conditions as in neurophysiological experiments. However, many currently used olfactory bioassays in Drosophila neuroethology are rather specialized either towards efficiency or towards resolution. Flywalk, an automated odor delivery and tracking system, bridges the gap between efficiency and resolution. It allows the determination of exactly when an odor packet stimulated a freely walking fly, and to determine the animal´s dynamic behavioral reaction.

Visual orientation processing in autism spectrum disorder: No sign of enhanced early cortical function

It has been suggested that enhanced perceptual processing underlies some of the social difficulties associated with autism spectrum disorder (ASD). While a variety of visual tasks have been reported in which individuals with ASD outperform neurotypical individuals in control groups, the precise origin of such effects within the visual pathway remains unclear. It has recently been established that visual acuity is intact yet unremarkable in ASD. This suggests that the earliest levels of retinal processing are an unlikely candidate as the source of differences. The next potential levels for divergent visual processing are those involved in processing simple aspects of visual stimuli, such as orientation and spatial frequency, considered to be functions of early visual cortex. Here we focused on the basic processing of orientation. In three experiments, we assessed three basic aspects of orientation processing-discrimination, veridical perception, and detection-in participants with ASD in comparison to age-, gender-, and IQ-matched adults without ASD. Each experiment allowed for both qualitative and quantitative comparisons between the two groups. These provided a dense array of data indicating that participants with ASD perceive orientation of low-level stimuli in a qualitatively (as well as quantitatively) similar manner to participants without ASD in control groups, with no evidence of superior processing in detection, precision, or accuracy aspects of orientation perception. These results suggest that the source for altered perceptual abilities should be sought elsewhere, possibly in specific subgroups of people with ASD, other aspects of low-level vision such as spatial frequency, or subsequent levels of visual processing.

Associative learning and sensory neuroplasticity: how does it happen and what is it good for?

Historically, the body's sensory systems have been presumed to provide the brain with raw information about the external environment, which the brain must interpret to select a behavioral response. Consequently, studies of the neurobiology of learning and memory have focused on circuitry that interfaces between sensory inputs and behavioral outputs, such as the amygdala and cerebellum. However, evidence is accumulating that some forms of learning can in fact drive stimulus-specific changes very early in sensory systems, including not only primary sensory cortices but also precortical structures and even the peripheral sensory organs themselves. This review synthesizes evidence across sensory modalities to report emerging themes, including the systems’ flexibility to emphasize different aspects of a sensory stimulus depending on its predictive features and ability of different forms of learning to produce similar plasticity in sensory structures. Potential functions of this learning-induced neuroplasticity are discussed in relation to the challenges faced by sensory systems in changing environments, and evidence for absolute changes in sensory ability is considered. We also emphasize that this plasticity may serve important nonsensory functions, including balancing metabolic load, regulating attentional focus, and facilitating downstream neuroplasticity.

It takes two-coincidence coding within the dual olfactory pathway of the honeybee.

To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g., in auditory delay lines). Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs) that transfer information from the primary olfactory centers, the antennal lobe (AL), to a multimodal integration center, the mushroom body (MB). PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code).

A methodological investigation of the Intermodal Preferential Looking paradigm: Methods of analyses, picture selection and data rejection criteria

The Intermodal Preferential Looking paradigm provides a sensitive measure of a child's online word comprehension. To complement existing recommendations (Fernald, Zangl, Portillo, & Marchman, 2008), the present study evaluates the impact of experimental noise generated by two aspects of the visual stimuli on the robustness of familiar word recognition with and without mispronunciations: the presence of a central fixation point and the level of visual noise in the pictures (as measured by luminance saliency). Twenty-month-old infants were presented with a classic word recognition IPL procedure in 3 conditions: without a fixation stimulus (No Fixation – noisiest condition), with a fixation stimulus before trial onset (Fixation, intermediate), and with a fixation stimulus, a neutral background and equally salient images (Fixation Plus – least noisy). Data were systematically analyzed considering a range of data selection criteria and dependent variables (proportion of looking time towards the target, longest look, and time-course analysis). Critically, the expected pronunciation and naming interaction was only found in the Fixation Plus condition. We discuss the impact of data selection criteria and the dependent variable choice on the modulation of these effects across the different conditions.

Functional specialization of the male insula during taste perception

The primary gustatory area is located in the insular cortex. Although the insular cortex has been the topic of multiple parcellation studies, its functional specialization regarding taste processing received relatively little attention. Studies investigating the brain response to taste suggested that the insular cortex is involved in processing multiple characteristics of a taste stimulus, such as its quality, intensity, and pleasantness. In the current functional magnetic resonance study, younger and older adult male subjects were exposed to four basic tastes in five increasing concentrations. We applied a data-driven analysis to obtain insular response maps, which showed that the insular cortex processes the presence of taste, its corresponding pleasantness, as well as its concentration. More specifically, the left and right insular cortices are differentially engaged in processing the aforementioned taste characteristics: representations of the presence of a taste stimulus as well as its corresponding pleasantness dominate in the left insular cortex, whereas taste concentration processing dominates in the right insular cortex. These results were similar across both age groups. Our results fit well within previous cytoarchitectural studies and show insular lateralization in processing different aspects of taste stimuli in men.

Impairments in musical abilities reflected in the auditory brainstem: evidence from congenital amusia.

Congenital amusia is a neurogenetic condition, characterized by a deficit in music perception and production, not explained by hearing loss, brain damage or lack of exposure to music. Despite inferior musical performance, amusics exhibit normal auditory cortical responses, with abnormal neural correlates suggested to lie beyond auditory cortices. Here we show, using auditory brainstem responses to complex sounds in humans, that fine-grained automatic processing of sounds is impoverished in amusia. Compared with matched non-musician controls, spectral amplitude was decreased in amusics for higher harmonic components of the auditory brainstem response. We also found a delayed response to the early transient aspects of the auditory stimulus in amusics. Neural measures of spectral amplitude and response timing correlated with participants' behavioral assessments of music processing. We demonstrate, for the first time, that amusia affects how complex acoustic signals are processed in the auditory brainstem. This neural signature of amusia mirrors what is observed in musicians, such that the aspects of the auditory brainstem responses that are enhanced in musicians are degraded in amusics. By showing that gradients of music abilities are reflected in the auditory brainstem, our findings have implications not only for current models of amusia but also for auditory functioning in general.

Left dominance for language perception starts in the extrastriate cortex: An ERP and sLORETA study

While it is well known that the left hemisphere is more efficient than the right in most tasks involving perception of speech stimuli, the neurophysiological pathways leading to these lateralised performance differences are as yet rather unclear. In particular, the question whether language lateralisation depends on semantic processing or is already evident in early perceptual stimulus processing has not been answered unequivocally. In the present study, we therefore recorded event-related potentials (ERPs) during tachistoscopic presentation of horizontally or vertically presented verbal stimuli in the left (LVF) and the right visual field (RVF). Participants were asked to indicate, whether the presented stimulus was a word or a non-word. On the behavioural level, participants showed stronger hemispheric asymmetries for horizontal, than for vertical stimulus presentation. In addition, ERP asymmetries were also modulated by stimulus presentation format, as the electrode by visual field interactions for P1 and N1 were stronger after vertical, than after horizontal stimulus presentation. Moreover, sLORETA revealed that ERP left-right asymmetries were mainly driven by the extrastriate cortex and reading-associated areas in the parietal cortex. Taken together, the present study shows electrophysiological support for the assumption that language lateralisation during speech perception arises from a left dominance for the processing of early perceptual stimulus aspects.

Can two dots form a Gestalt? Measuring emergent features with the capacity coefficient

While there is widespread agreement among vision researchers on the importance of some local aspects of visual stimuli, such as hue and intensity, there is no general consensus on a full set of basic sources of information used in perceptual tasks or how they are processed. Gestalt theories place particular value on emergent features, which are based on the higher-order relationships among elements of a stimulus rather than local properties. Thus, arbitrating between different accounts of features is an important step in arbitrating between local and Gestalt theories of perception in general. In this paper, we present the capacity coefficient from Systems Factorial Technology (SFT) as a quantitative approach for formalizing and rigorously testing predictions made by local and Gestalt theories of features. As a simple, easily controlled domain for testing this approach, we focus on the local feature of location and the emergent features of Orientation and Proximity in a pair of dots. We introduce a redundant-target change detection task to compare our capacity measure on (1) trials where the configuration of the dots changed along with their location against (2) trials where the amount of local location change was exactly the same, but there was no change in the configuration. Our results, in conjunction with our modeling tools, favor the Gestalt account of emergent features. We conclude by suggesting several candidate information-processing models that incorporate emergent features, which follow from our approach.

Attentional biases towards familiar and unfamiliar foods in children. The role of food neophobia

Familiarity of food stimuli is one factor that has been proposed to explain food preferences and food neophobia in children, with some research suggesting that food neophobia (and familiarity) is at first a predominant of the visual domain. Considering visual attentional biases are a key factor implicated in a majority of fear-related phobias/anxieties, the purpose of this research was to investigate attentional biases to familiar and unfamiliar fruit and vegetables in 8 to 11 year old children with differing levels of food neophobia. To this end, 70 primary aged children completed a visual-probe task measuring attentional biases towards familiar and unfamiliar fruit/vegetables, as well as the food neophobia, general neophobia and willingness to try self-report measures. Results revealed that as an undifferentiated population all children appeared to demonstrate an attentional bias towards the unfamiliar fruit and vegetable stimuli. However, when considering food neophobia, this bias was significantly exaggerated for children self-reporting high food neophobia and negligible for children self-reporting low food neophobia. In addition, willingness to try the food stimuli was inversely correlated with attentional bias towards the unfamiliar fruits/vegetables. Our results demonstrate that visual aspects of food stimuli (e.g. familiarity) play an important role in childhood food neophobia. This study provides the first empirical test of recent theory/models of food neophobia (e.g. Brown & Harris, 2012). Findings are discussed in light of these models and related anxiety models, along with implications concerning the treatment of childhood food neophobia.