Properties Of Visual Stimuli Research Articles

Flight patterns of monocularly occluded homing pigeons further reveal a left eye/right cerebral hemispheric advantage in the visual processing of familiar landscape/landmark features

Studying pigeons during homing has offered an opportunity to investigate visual–functional brain lateralization in the context of free flying and long distance navigation. In the current study we examine at a high scale of spatial resolution the flight paths of pigeons, which vary with respect to monocular and binocular treatment, as they familiarise themselves with landscape and landmark features during repeated flights home from two locations. The analysis of the flight paths of monocularly occluded pigeons revealed that pigeons using the right eye/left hemisphere visual system were more likely to display more tortuous paths over tracts of 500 m along the flight path home compared to both pigeons using the left eye/right hemisphere visual system and control birds. Accompanying this finding was the observation that pigeons using the right eye/left hemisphere system were more likely to perform flight “loops”, suggesting that, without right hemispheric visual processing, pigeons are more motivated to seek out visual input, behaviourally expanding the now monocularly reduced visual field. Taken together, the data are consistent with a more important role of the left eye/right hemisphere system in processing visual features of the landscape, which may contribute to the construction of the familiar landmark-based map used for navigation. More broadly, our data are consistent with the hypothesis that the right cerebral hemisphere of the avian brain plays a more important role in memorising and using the relational properties of visual stimuli to guide performance on spatial tasks.

Pervasive failure to report properties of visual stimuli in experimental research in psychology and neuroscience: Two metascientific studies.

Pervasive failure to report properties of visual stimuli in experimental research in psychology and neuroscience: Two metascientific studies.

Continuous Theta-Burst Stimulation of the Primary Motor Cortex Induces Specific Influence on Novel Vocabulary Acquisition in Different Learning Environments

The primary motor cortex takes part in various stages of language learning accompanied by human motor activity. However, previous studies of causal relationships between the activation of primary motor cortex and efficiency of language tasks reveal contradictory results, likely due to diverging learning environments and specific movement patterns required by different experimental designs. The goal of this research was to comprehensively investigate the effect of continuous theta-burst magnetic stimulation (cTBS) of the primary motor cortex on the acquisition of new words while modulating the learning environment and the motor response during the learning process. Following cTBS of the primary motor cortex or control conditions (sham and active control cTBS), the subjects (n = 96) completed a novel word learning task, which involved associating visually presented objects with spoken word forms using a virtual reality (VR) or conventional computer monitor environment. In each environment, the subjects were exposed to eight novel words embedded into questions about visual stimulus properties in order to prompt novel associations. Responses to these questions could be performed either by distal or by proximal hand movements. The outcome of the word acquisition was measured using a free recall task immediately after the training and on the next day. The results showed significant differences in the success of recalling new words immediately after the learning session and on the next day only in those subjects who received cTBS of the primary motor cortex; furthermore, this effect was specific to proximal movements in both learning environments. The results suggest that the motor cortex is directly involved in acquiring novel vocabulary during active interaction with the learning material.

Seeing the forest or the tree depends on personality: Evidence from process communication model during global/local visual search task.

In everyday life, we are continuously confronted with multiple levels of visual information processes (e.g., global information, the forest, and local information, the tree) and we must select information that has to be processed. In the present study, we investigated the relation between personality and the ability to process global and local visual information. Global precedence phenomenon was assessed by a standard global/local visual search task used in many visuo-spatial precedent studies, and the 77 participants were also presented with the standard Process Communication Model (PCM) questionnaire. Results suggest that the ability to process global and local properties of visual stimuli varied according to the Base type of participants. Even if four among six Base types (Thinker, Persister, Harmonizer and Promoter) presented a classical global visual precedence, the two other Base types (Rebel and Imaginer) presented only an effect of distractors and an effect of global advantage, respectively. Taken together, these results evidenced that each human being does not equally perceive the "forest" (global information) and the "tree" (local information). Even if objectively presented with similar visual stimuli, individual responses differ according to the Base, an inter-individual variability that could be taken into account during daily life situations.

Role of Rostral Superior Colliculus in Gaze Stabilization during Visual Fixation.

Visual fixation (i.e., holding gaze on a specific visual object or location of interest) has been shown to be influenced by activity in the rostral pole of the intermediate layers of the superior colliculus (SCi)-a sensory-motor integration nucleus in the midbrain involved in visual fixation and saccadic eye movement generation. Neurons in the rostral SCi discharge tonically during visual fixation and pause during saccades to locations beyond their foveal visual-sensory or saccadic-motor response fields. Injection of muscimol to deactivate rostral SCi neurons also leads to an increase in fixation instability. However, the precise role of rostral SCi activity for controlling visual fixation has not been established and is actively debated. Here, we address whether this activity reflects signals related to task demands (i.e., maintaining visual fixation) or foveal visual stimulus properties. Two non-human primates performed an oculomotor task that required fixation of a central fixation point (FP) of varying luminance at the start of each trial. During this fixation period, we measured fixational saccades (≤ 2° of the FP, including microsaccades) and fixation-error saccades (> 2° from the FP) in combination with activity from the rostral SCi. Fixation of the lowest FP luminance increased the latency (onset time relative to initial FP foveation) for both fixational and fixation-error saccades. Fifty percent of the rostral SCi neurons exhibited activity that opposed the change in FP luminance and correlated with delayed fixational saccades and increased fixation-error saccades. Twenty-two percent of rostral SCi neurons exhibited activity that followed the change in FP luminance and correlated with earlier fixational saccades and decreased fixation-error saccades. This suggests the rostral SCi contains both sensory-driven and task-related motor signals related to foveal sensory stimuli and visual fixation. This evidence supports a role for the rostral SCi in gaze stabilization and can help inform artificial computational models of vision.

Supplemental Material for Pervasive Failure to Report Properties of Visual Stimuli in Experimental Research in Psychology and Neuroscience: Two Metascientific Studies

Supplemental Material for Pervasive Failure to Report Properties of Visual Stimuli in Experimental Research in Psychology and Neuroscience: Two Metascientific Studies

Cortical VIP neurons locally control the gain but globally control the coherence of gamma band rhythms

Gamma band synchronization can facilitate local and long-range neural communication. In the primary visual cortex, visual stimulus properties within a specific location determine local synchronization strength, while the match of stimulus properties between distant locations controls long-range synchronization. The neural basis for the differential control of local and global gamma band synchronization is unknown. Combining electrophysiology, optogenetics, and computational modeling, we found that VIP disinhibitory interneurons in mouse cortex linearly scale gamma power locally without changing its stimulus tuning. Conversely, they suppress long-range synchronization when two regions process non-matched stimuli, tuning gamma coherence globally. Modeling shows that like-to-like connectivity across space and specific VIP→SST inhibition capture these opposing effects. VIP neurons thus differentially impact local and global properties of gamma rhythms depending on visual stimulus statistics. They may thereby construct gamma-band filters for spatially extended but continuous image features, such as contours, facilitating the downstream generation of coherent visual percepts.

The effect of perceptual history on the interpretation of causality.

The ability to interpret spatiotemporal contingencies in terms of causal relationships plays a key role in human understanding of the external world. Indeed, the detection of such simple properties enables us to attribute causal attributes to interactions between objects. Here, we investigated the degree to which this perception of causality depends on recent experience, as has been found for other low-level properties of visual stimuli. Participants were shown launching sequences of colliding circles with varying collision lags and were asked to report their impression of causality. We found short-term attractive and long-term repulsive and attractive effects of perceptual history on the interpretation of causality. Stimuli directly following a causal impression were more likely to be judged as causal and vice versa. However, prior judgments on less recent (>5) trials biased current perception with both positive/attractive and negative/repulsive influences. We interpret these results in terms of two potential mechanisms: adaptive temporal binding windows and updating of internal representations of causality. Overall, these results demonstrate the important role of prior experience even for causality, a fundamental building block of how we understand our world.

Functional Coupling of the Locus Coeruleus Is Linked to Successful Cognitive Control.

The locus coeruleus (LC) is a brainstem structure that sends widespread efferent projections throughout the mammalian brain. The LC constitutes the major source of noradrenaline (NE), a modulatory neurotransmitter that is crucial for fundamental brain functions such as arousal, attention, and cognitive control. This role of the LC-NE is traditionally not believed to reflect functional influences on the frontoparietal network or the striatum, but recent advances in chemogenetic manipulations of the rodent brain have challenged this notion. However, demonstrations of LC-NE functional connectivity with these areas in the human brain are surprisingly sparse. Here, we close this gap. Using an established emotional stroop task, we directly compared trials requiring response conflict control with trials that did not require this, but were matched for visual stimulus properties, response modality, and controlled for pupil dilation differences across both trial types. We found that LC-NE functional coupling with the parietal cortex and regions of the striatum is substantially enhanced during trials requiring response conflict control. Crucially, the strength of this functional coupling was directly related to individual reaction time differences incurred by conflict resolution. Our data concur with recent rodent findings and highlight the importance of converging evidence between human and nonhuman neurophysiology to further understand the neural systems supporting adaptive and maladaptive behavior in health and disease.

Sensory representation of visual stimuli in the coupling of low-frequency phase to spike times.

Neural synchronization has been engaged in several brain mechanisms. Previous studies have shown that the interaction between the time of spiking activity and phase of local field potentials (LFPs) plays a key role in many cognitive functions. However, the potential role of this spike-LFP phase coupling (SPC) in neural coding is not fully understood. Here, we sought to investigate the role of this SPC for encoding the sensory properties of visual stimuli. To this end, we measured SPC strength in the preferred and anti-preferred motion directions of stimulus presented inside the receptive field of middle temporal (MT) neurons. We found a selective response in terms of SPC strength for different directions of motion. Remarkably, this selective function is inverted with respect to the spiking activity. In other words, the least SPC occurs for the preferred direction (based on the spike rate), and vice versa; the strongest SPC is induced in the anti-preferred direction. Altogether, these findings imply that the neural system may use spike-LFP phase coupling in the primate visual cortex to encode sensory information.

Estimating null and potent modes of feedforward communication in a computational model of cortical activity

Communication across anatomical areas of the brain is key to both sensory and motor processes. Dimensionality reduction approaches have shown that the covariation of activity across cortical areas follows well-delimited patterns. Some of these patterns fall within the "potent space" of neural interactions and generate downstream responses; other patterns fall within the "null space" and prevent the feedforward propagation of synaptic inputs. Despite growing evidence for the role of null space activity in visual processing as well as preparatory motor control, a mechanistic understanding of its neural origins is lacking. Here, we developed a mean-rate model that allowed for the systematic control of feedforward propagation by potent and null modes of interaction. In this model, altering the number of null modes led to no systematic changes in firing rates, pairwise correlations, or mean synaptic strengths across areas, making it difficult to characterize feedforward communication with common measures of functional connectivity. A novel measure termed the null ratio captured the proportion of null modes relayed from one area to another. Applied to simultaneous recordings of primate cortical areas V1 and V2 during image viewing, the null ratio revealed that feedforward interactions have a broad null space that may reflect properties of visual stimuli.

Population Models, Not Analyses, of Human Neuroscience Measurements.

Selectivity for many basic properties of visual stimuli, such as orientation, is thought to be organized at the scale of cortical columns, making it difficult or impossible to measure directly with noninvasive human neuroscience measurement. However, computational analyses of neuroimaging data have shown that selectivity for orientation can be recovered by considering the pattern of response across a region of cortex. This suggests that computational analyses can reveal representation encoded at a finer spatial scale than is implied by the spatial resolution limits of measurement techniques. This potentially opens up the possibility to study a much wider range of neural phenomena that are otherwise inaccessible through noninvasive measurement. However, as we review in this article, a large body of evidence suggests an alternative hypothesis to this superresolution account: that orientation information is available at the spatial scale of cortical maps and thus easily measurable at the spatial resolution of standard techniques. In fact, a population model shows that this orientation information need not even come from single-unit selectivity for orientation tuning, but instead can result from population selectivity for spatial frequency. Thus, a categorical error of interpretation can result whereby orientation selectivity can be confused with spatial frequency selectivity. This is similarly problematic for the interpretation of results from numerous studies of more complex representations and cognitive functions that have built upon the computational techniques used to reveal stimulus orientation. We suggest in this review that these interpretational ambiguities can be avoided by treating computational analyses as models of the neural processes that give rise to measurement. Building upon the modeling tradition in vision science using considerations of whether population models meet a set of core criteria is important for creating the foundation for a cumulative and replicable approach to making valid inferences from human neuroscience measurements.

To Name or Not to Name: Eye Movements and Semantic Processing in RAN and Reading.

This study examined the well-established relationship between rapid naming and reading. Rapid automatized naming (RAN) has long been demonstrated as a strong predictor of reading abilities. Despite extensive research spanning over 4 decades, the underlying mechanisms of these causes remain a subject of inquiry. The current study investigated the role of eye movements and semantic processing in defining the RAN-reading relationship. The participants in this study were 42 English-speaking undergraduate students at a British university. The materials included a word reading task, two conventional RAN tasks (object and digit), and two RAN-like categorization tasks (object and digit). The results obtained suggested the interdependence between rapid naming and semantic processing. Hierarchical multiple regression analyses revealed that oculomotor control remains an integral part of variability in RAN and reading performance. Taken together, our results suggest that RAN and reading measures are correlated because both require rapid and accurate retrieval of phonological representations, semantic properties of visual stimuli, and stable co-ordination of eye movements.

Pictorial low-level features in mental images: evidence from eye fixations.

It is known that eye movements during object imagery reflect areas visited during encoding. But will eye movements also reflect pictorial low-level features of imagined stimuli? In this paper, three experiments are reported in which we investigate whether low-level properties of mental images elicit specific eye movements. Based on the conceptualization of mental images as depictive representations, we expected low-level visual features to influence eye fixations during mental imagery, in the absence of a visual input. In a first experiment, twenty-five participants performed a visual imagery task with high vs. low spatial frequency and high vs. low contrast gratings. We found that both during visual perception and during mental imagery, first fixations were more often allocated to the low spatial frequency-high contrast grating, thus showing that eye fixations were influenced not only by physical properties of visual stimuli but also by its imagined counterpart. In a second experiment, twenty-two participants imagined high contrast and low contrast stimuli that they had not encoded before. Again, participants allocated more fixations to the high contrast mental images than to the low contrast mental images. In a third experiment, we ruled out task difficulty as confounding variable. Our results reveal that low-level visual features are represented in the mind's eye and thus, they contribute to the characterization of mental images in terms of how much perceptual information is re-instantiated during mental imagery.

Visual Functions of Primate Area V4.

Area V4-the focus of this review-is a mid-level processing stage along the ventral visual pathway of the macaque monkey. V4 is extensively interconnected with other visual cortical areas along the ventral and dorsal visual streams, with frontal cortical areas, and with several subcortical structures. Thus, it is well poised to play a broad and integrative role in visual perception and recognition-the functional domain of the ventral pathway. Neurophysiological studies in monkeys engaged in passive fixation and behavioral tasks suggest that V4 responses are dictated by tuning in a high-dimensional stimulus space defined by form, texture, color, depth, and other attributes of visual stimuli. This high-dimensional tuning may underlie the development of object-based representations in the visual cortex that are critical for tracking, recognizing, and interacting with objects. Neurophysiological and lesion studies also suggest that V4 responses are important for guiding perceptual decisions and higher-order behavior.

Visual recognition memory for scenes in aerial photographs: Exploring the role of expertise

Aerial photographs depict objects from an overhead position, which gives them several unusual visual characteristics that are challenging for viewers to perceive and memorize. However, even for untrained viewers, aerial photographs are still meaningful and rich with contextual information. Such visual stimulus properties are considered appropriate and important when testing for expertise effects in visual recognition memory. The current experiment investigated memory recognition in expert image analysts and untrained viewers using two types of aerial photographs. The experts were better than untrained viewers at recognizing both vertical aerial photographs, which is the domain of their expertise, and oblique aerial photographs. Thus, one notable finding is that the superior memory performance of experts is not limited to a domain of expertise but extends to a broader category of large-scale landscape scenes. Furthermore, the experts' recognition accuracy remained relatively stable throughout the experimental conditions, illustrating the ability to use semantic information over strictly visual information in memory processes.

Legibility Assessment of Visual Word Form Symbols for Visual Tests

For a reliable visual test, it is important to evaluate the legibility of the symbols, which depends on several factors. Previous studies have compared the legibility of Latin optotypes. This study developed a visual function test based on identification visual capacity for a Chinese reading population. The legibility of word symbols was assessed with three methods: (1) Identification of the contrast thresholds of the character sets, (2) patterns of confusion matrices obtained from analysis of the frequency of incorrect stimulus/response pairs, and (3) pixel ratios of bitmap images of Chinese characters. Then characters of similar legibility in each character set were selected. The contrast thresholds of the final five character sets and the Tumbling E and Landolt C optotypes were evaluated. No significant differences in contrast threshold were found among the five selected character sets (p > 0.05), but the contrast thresholds were significantly higher than those of the E and C optotypes. Our results indicate that combining multiple methods to include the influences of the properties of visual stimuli would be useful in investigating the legibility of visual word symbols.

Common Functional Brain States Encode both Perceived Emotion and the Psychophysiological Response to Affective Stimuli

Multivariate pattern analysis (MVPA) of functional magnetic resonance imaging (fMRI) data has critically advanced the neuroanatomical understanding of affect processing in the human brain. Central to these advancements is the brain state, a temporally-succinct fMRI-derived pattern of neural activation, which serves as a processing unit. Establishing the brain state’s central role in affect processing, however, requires that it predicts multiple independent measures of affect. We employed MVPA-based regression to predict the valence and arousal properties of visual stimuli sampled from the International Affective Picture System (IAPS) along with the corollary skin conductance response (SCR) for demographically diverse healthy human participants (n = 19). We found that brain states significantly predicted the normative valence and arousal scores of the stimuli as well as the attendant individual SCRs. In contrast, SCRs significantly predicted arousal only. The prediction effect size of the brain state was more than three times greater than that of SCR. Moreover, neuroanatomical analysis of the regression parameters found remarkable agreement with regions long-established by fMRI univariate analyses in the emotion processing literature. Finally, geometric analysis of these parameters also found that the neuroanatomical encodings of valence and arousal are orthogonal as originally posited by the circumplex model of dimensional emotion.

Logical Connectives Modulate Attention to Simulations Evoked by the Constituents They Link Together.

In previous studies investigating logical-connectives simulations, participants focused their attention on verifying truth-condition satisfaction for connective expressions describing visual stimuli (e.g., Dumitru, 2014; Dumitru and Joergensen, 2016). Here, we sought to replicate and extend the findings that conjunction and disjunction simulations are structured as one and two Gestalts, respectively, by using language – picture matching tasks where participants focused their attention exclusively on stimuli visuospatial properties. Three studies evaluated perceptual compatibility effects between visual displays varying stimuli direction, size, and orientation, and basic sentences featuring the logical connectives AND, OR, BUT, IF, ALTHOUGH, BECAUSE, and THEREFORE (e.g., “There is blue AND there is red”). Response times highlight correlations between the Gestalt arity of connective simulations and visual attention patterns, such that words referring to constituents in the same Gestalt were matched faster to visual stimuli displayed sequentially rather than alternatively, having the same size rather than different sizes, and being oriented along axes other than horizontal. The results also highlight attentional patterns orthogonal to Gestalt arity: visual stimuli corresponding to simulation constituents were processed faster when they appeared onscreen from left to right than from right to left, when they were emphasized or de-emphasized together (i.e., faster processing of all-small or all-large stimuli pairs), and when they formed a downward-oriented diagonal, which signals a simulation boundary. More generally, our findings suggest that logical connectives rapidly evoke simulations that trigger top-down attention patterns over the grouping and properties of visual stimuli corresponding to the constituents they link together.

Motion onset really does capture attention.

Several properties of visual stimuli have been shown to capture attention, one of which is the onset of motion. However, whether motion onset truly captures attention has been debated. It has been argued that motion onset only captured attention in previous studies because properties of the animated motion used in those experiments caused it to be "jerky" (i.e., there were gaps between successive images during animated motion). The present study sought to determine whether natural motion onset captures attention. Additionally, the present study further examined the circumstances under which animated motion onset, the only type of motion onset that can be produced on a computer display, does and does not capture attention. In Experiment 1, participants identified target letters in search arrays containing distinct animated motion types, either accompanied or unaccompanied by a new object. Animated motion onset captured attention, but not when the motion onset was accompanied by a new object, indicating that prior failures to replicate capture by animated motion onset were limited because a new object had always been included in the display. Experiment 2 employed natural motion rather than animated motion and found that participants were fastest at identifying motion-onset targets compared to other target types. These results provide further support for the claim that motion onset captures attention.