scholarly journals The perception of color and material in naturalistic tasks

2018 ◽  
Author(s):  
David H. Brainard ◽  
Nicolas P. Cottaris ◽  
Ana Radonjić
Keyword(s):  
Visual Processing ◽  
Early Vision ◽  
Object Surface ◽  
Future Directions ◽  
Vision Science ◽  
Simple Mapping ◽  
Observer Model ◽  
Key Aspects ◽  
Natural Tasks ◽  
Perceived Color

AbstractPerceived object color and material properties help us to select and interact with objects. Because there is no simple mapping between the pattern of an object’s image on the retina and its physical reflectance, our perception of color and material are made more useful through sophisticated visual computations. A long-standing goal in vision science is to describe how these computations work, particularly as they act to stabilize perceived color and material against variation in scene factors extrinsic to object surface properties, such as the illumination. If we take seriously the notion that perceived color and material are useful because they help guide behavior in natural tasks, then we need experimental that measure and models that describe how they are used in such tasks. To this end, we have developed selection-based methods and accompanying perceptual models for studying perceived object color and material. This focused review highlights key aspects of our work. It includes a discussion of future directions and challenges, as well as an outline of a computational observer model that incorporates early, known, stages of visual processing and that clarifies how early vision shapes selection performance.

scholarly journals The perception of colour and material in naturalistic tasks

2018 ◽  
Vol 8 (4) ◽  
pp. 20180012 ◽  
Author(s):  
David H. Brainard ◽  
Nicolas P. Cottaris ◽  
Ana Radonjić
Keyword(s):  
Surface Properties ◽  
Visual Processing ◽  
Early Vision ◽  
Object Surface ◽  
Future Directions ◽  
Vision Science ◽  
Simple Mapping ◽  
Observer Model ◽  
Key Aspects ◽  
Natural Tasks

Perceived object colour and material help us to select and interact with objects. Because there is no simple mapping between the pattern of an object's image on the retina and its physical reflectance, our perceptions of colour and material are the result of sophisticated visual computations. A long-standing goal in vision science is to describe how these computations work, particularly as they act to stabilize perceived colour and material against variation in scene factors extrinsic to object surface properties, such as the illumination. If we take seriously the notion that perceived colour and material are useful because they help guide behaviour in natural tasks, then we need experiments that measure and models that describe how they are used in such tasks. To this end, we have developed selection-based methods and accompanying perceptual models for studying perceived object colour and material. This focused review highlights key aspects of our work. It includes a discussion of future directions and challenges, as well as an outline of a computational observer model that incorporates early, known, stages of visual processing and that clarifies how early vision shapes selection performance.

Cardiac interoception in neurological conditions and its relevance for dimensional approaches

2018 ◽  
Author(s):  
Adrián Yoris ◽  
Adolfo M. García ◽  
Paula Celeste Salamone ◽  
Lucas Sedeño ◽  
Indira García-Cordero ◽  
...  
Keyword(s):  
Potential Role ◽  
Neurocognitive Deficits ◽  
Future Directions ◽  
Treatment And Prevention ◽  
Neurological Conditions ◽  
Key Aspects ◽  
The Relationship ◽  
General Source ◽  
Neuropsychiatric Conditions

Dimensional and transdiagnostic approaches have revealed multiple cognitive/emotional alterations shared by several neuropsychiatric conditions. While this has been shown for externally triggered neurocognitive processes, the disruption of interoception across neurological disorders remains poorly understood. This chapter aims to fill this gap while proposing cardiac interoception as a potential common biomarker across disorders. It focuses on key aspects of interoception, such as the mechanisms underlying different interoceptive dimensions; the relationship among interoception, emotion, and social cognition; and the roles of different interoceptive pathways. It considers behavioral and brain evidence in the context of an experimental and clinical agenda to evaluate the potential role of interoception as a predictor of clinical outcomes, a marker of neurocognitive deficits across diseases, and a general source of insights for breakthroughs in the treatment and prevention of multiple disorders. Finally, future directions to improve the dimensional and transdiagnostic assessment of interoception are outlined.

scholarly journals Minor hallucinations in Parkinson disease

Neurology ◽  
2019 ◽  
Vol 93 (6) ◽  
pp. 259-266 ◽  
Author(s):  
Abhishek Lenka ◽  
Javier Pagonabarraga ◽  
Pramod Kumar Pal ◽  
Helena Bejr-Kasem ◽  
Jaime Kulisvesky
Keyword(s):  
Parkinson Disease ◽  
Visual Processing ◽  
Brain Connectivity ◽  
Rem Sleep Behavior Disorder ◽  
Behavior Disorder ◽  
Future Directions ◽  
Sleep Behavior ◽  
Control Networks ◽  
Pubmed Search ◽  
Prognostic Implications

ObjectivePsychosis is one of the most debilitating complications of Parkinson disease (PD). Although research on PD psychosis has been focused on the study of well-structured visual hallucinations (VH), currently accepted National Institute of Neurological Disorders and Stroke–National Institute of Mental Health diagnostic criteria emphasize minor hallucinations (MH) as the most common psychotic phenomena in PD. The objective of this review is to comprehensively describe the clinical and research advances on the understanding of MH and to provide future directions for obtaining further insights into their potential major implications for PD management and prognosis.MethodsA PubMed search was done in November 2018 to identify articles on minor psychotic phenomena in PD.ResultsMH often precede the onset of well-structured VH and are associated with other nonmotor symptoms such as REM sleep behavior disorder and depression. The pattern of functional brain connectivity changes associated with MH involve visual-processing areas and attention control networks, which overlap with abnormalities described in patients with well-structured VH. The dysfunction of cortical networks in patients with MH may be an early indicator of a more widespread form of the disease.ConclusionAlthough called “minor,” MH may have major clinical and prognostic implications. Further research is needed to establish whether MH are associated with a higher risk of disabling psychotic complications, cognitive deterioration, or a more accelerated disease progression. Understanding the early neurobiological underpinnings of MH may provide the background for future studies to identify the progressive dysfunction of neural circuits leading to more severe forms of psychosis in PD.

Role of Feedback Connections in Central Visual Processing

2020 ◽  
Vol 6 (1) ◽  
pp. 313-334
Author(s):  
Farran Briggs
Keyword(s):  
Visual Processing ◽  
Physiological Response ◽  
Functional Role ◽  
Functional Roles ◽  
Vision Science ◽  
The Core ◽  
Feedback Circuits ◽  
Corticothalamic Feedback ◽  
Feedback Connections

The physiological response properties of neurons in the visual system are inherited mainly from feedforward inputs. Interestingly, feedback inputs often outnumber feedforward inputs. Although they are numerous, feedback connections are weaker, slower, and considered to be modulatory, in contrast to fast, high-efficacy feedforward connections. Accordingly, the functional role of feedback in visual processing has remained a fundamental mystery in vision science. At the core of this mystery are questions about whether feedback circuits regulate spatial receptive field properties versus temporal responses among target neurons, or whether feedback serves a more global role in arousal or attention. These proposed functions are not mutually exclusive, and there is compelling evidence to support multiple functional roles for feedback. In this review, the role of feedback in vision will be explored mainly from the perspective of corticothalamic feedback. Further generalized principles of feedback applicable to corticocortical connections will also be considered.

Pilots for change: exploring organisational change through distributed leadership

2014 ◽  
Vol 35 (2) ◽  
pp. 152-167 ◽  
Author(s):  
Steve Kempster ◽  
Malcolm Higgs ◽  
Tobias Wuerz
Keyword(s):  
Change Management ◽  
Distributed Leadership ◽  
Organisational Change ◽  
Change Leadership ◽  
Theoretical Argument ◽  
Future Directions ◽  
Content Type ◽  
Research Propositions ◽  
Key Aspects ◽  
Practical Implications

Purpose – Little is known about how and why pilots are useful in the context of organisational change. There has similarly been little attention to processes of distributed leadership in organisational change. The purpose of this paper is to develop a theoretical argument relating to how key aspects shaping organisational change can be addressed by distributed change leadership through the mechanism of pilots. Design/methodology/approach – The paper contribution is to review extant literature on change management and distributed leadership to build a model of distributed change leadership. Findings – The paper outlines how the model of distributed change leadership can be applied through a pilot strategy to help engender commitment and learning, as well as contextualising the change to cope with the complexities of the situation. Practical implications – The paper concludes with a discussion on the opportunities distributed leadership through pilots can bring to the effectiveness of organisational change interventions. The paper identifies a series of research propositions to help guide future directions for research. Finally the paper explores practical implications of the suggestions. Originality/value – There is an absence of discussion on distributed leadership within the context of change management. Further the mechanism of pilots shaped by distributed leadership has not been explored. This paper is intended to provide a stimulus for exploring this important area in terms of shaping thinking and designs for organisational change to enhance effectiveness.

Visual Function, Organization, and Development of the Mouse Superior Colliculus

2018 ◽  
Vol 4 (1) ◽  
pp. 239-262 ◽  
Author(s):  
Jianhua Cang ◽  
Elise Savier ◽  
Jad Barchini ◽  
Xiaorong Liu
Keyword(s):  
Superior Colliculus ◽  
Visual Processing ◽  
Great Promise ◽  
Visual Response ◽  
Visually Guided ◽  
Future Directions ◽  
Visual Center ◽  
Cell Type Specific ◽  
The Rich ◽  
Mouse Vision

The superior colliculus (SC) is the most prominent visual center in mice. Studies over the past decade have greatly advanced our understanding of the function, organization, and development of the mouse SC, which has rapidly become a popular model in vision research. These studies have described the diverse and cell-type-specific visual response properties in the mouse SC, revealed their laminar and topographic organizations, and linked the mouse SC and downstream pathways with visually guided behaviors. Here, we summarize these findings, compare them with the rich literature of SC studies in other species, and highlight important gaps and exciting future directions. Given its clear importance in mouse vision and the available modern neuroscience tools, the mouse SC holds great promise for understanding the cellular, circuit, and developmental mechanisms that underlie visual processing, sensorimotor transformation, and, ultimately, behavior.

scholarly journals Comparing Candidate Selection: A Feminist Institutionalist Approach

2016 ◽  
Vol 51 (3) ◽  
pp. 370-392 ◽  
Author(s):  
Elin Bjarnegård ◽  
Meryl Kenny
Keyword(s):  
Political Parties ◽  
Comparative Studies ◽  
Research Agenda ◽  
Selection Process ◽  
Institutional Context ◽  
Analytical Framework ◽  
Candidate Selection ◽  
Future Directions ◽  
Political Dominance ◽  
Key Aspects

This contribution evaluates the theoretical and methodological challenges of researching the gendered dynamics of candidate selection in comparative perspective. It argues that comparative studies should take into account not only the gendered nature of political parties and their wider institutional context, but must also investigate the informal aspects of the selection process and their gendered consequences. The article explores these dynamics by revisiting original in-depth research on the candidate selection process in two different settings – Thailand and Scotland. Using a common analytical framework, the article reflects on this work and points to two key aspects of the interaction between formal and informal rules – the gendered consequences of informal party recruitment and of local influence over candidate selection – which are critically important for understanding the continuity of male political dominance and female under-representation. The article concludes by outlining a research agenda for comparative work on gender, institutions and candidate selection and pointing to future directions for work in this area.

scholarly journals Test-retest reliability for common tasks in vision science

2021 ◽  
Author(s):  
Kait Clark ◽  
Kayley Birch-Hurst ◽  
Charlotte Rebecca Pennington ◽  
Austin C P Petrie ◽  
Joshua Lee ◽  
...  
Keyword(s):  
Individual Differences ◽  
Undergraduate Students ◽  
Visual Processing ◽  
Human Cognition ◽  
Cognitive Mechanisms ◽  
Retest Reliability ◽  
Vision Science ◽  
Intraclass Correlations ◽  
Low Levels ◽  
Test Retest Reliability

Research in perception and attention has typically sought to evaluate cognitive mechanisms according to the average response to a manipulation. Recently, there has been a shift toward appreciating the value of individual differences and the insight gained by exploring the impacts of between-participant variation on human cognition. However, a recent study suggests that many robust, well-established cognitive control tasks suffer from surprisingly low levels of test-retest reliability (Hedge et al., 2018b). We tested a large sample of undergraduate students (n = 160) in two sessions (separated by 1–3 weeks) on four commonly used tasks in vision science. We implemented measures that spanned the range of visual processing, including motion coherence (MoCo), useful field of view (UFOV), multiple-object tracking (MOT), and visual working memory (VWM). Intraclass correlations ranged from excellent to poor suggesting that some task measures are more suitable for assessing individual differences than others. VWM capacity (ICC = 0.89), MoCo threshold (ICC = 0.60), UFOV middle accuracy (ICC = 0.60) and UFOV outer accuracy (ICC = 0.74) showed good-to-excellent reliability. Other measures, namely the maximum number of items tracked in MOT (ICC = 0.41) and UFOV number accuracy (ICC = 0.48), showed moderate reliability; the MOT threshold (ICC = 0.36) and UFOV inner accuracy (ICC = 0.30) showed poor reliability. In this paper, we present these results alongside a summary of reliabilities estimated previously for other vision science tasks. We then offer useful recommendations for evaluating test-retest reliability when considering a task for use in evaluating individual differences.

scholarly journals Asymmetries around the visual field: From retina to cortex to behavior

2022 ◽  
Vol 18 (1) ◽  
pp. e1009771
Author(s):  
Eline R. Kupers ◽  
Noah C. Benson ◽  
Marisa Carrasco ◽  
Jonathan Winawer
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Polar Angle ◽  
Spatial Filtering ◽  
Orientation Discrimination ◽  
Support Vector ◽  
Additional Contribution ◽  
Full Account ◽  
Observer Model ◽  
Cone Density

Visual performance varies around the visual field. It is best near the fovea compared to the periphery, and at iso-eccentric locations it is best on the horizontal, intermediate on the lower, and poorest on the upper meridian. The fovea-to-periphery performance decline is linked to the decreases in cone density, retinal ganglion cell (RGC) density, and V1 cortical magnification factor (CMF) as eccentricity increases. The origins of polar angle asymmetries are not well understood. Optical quality and cone density vary across the retina, but recent computational modeling has shown that these factors can only account for a small percentage of behavior. Here, we investigate how visual processing beyond the cone photon absorptions contributes to polar angle asymmetries in performance. First, we quantify the extent of asymmetries in cone density, midget RGC density, and V1 CMF. We find that both polar angle asymmetries and eccentricity gradients increase from cones to mRGCs, and from mRGCs to cortex. Second, we extend our previously published computational observer model to quantify the contribution of phototransduction by the cones and spatial filtering by mRGCs to behavioral asymmetries. Starting with photons emitted by a visual display, the model simulates the effect of human optics, cone isomerizations, phototransduction, and mRGC spatial filtering. The model performs a forced choice orientation discrimination task on mRGC responses using a linear support vector machine classifier. The model shows that asymmetries in a decision maker’s performance across polar angle are greater when assessing the photocurrents than when assessing isomerizations and are greater still when assessing mRGC signals. Nonetheless, the polar angle asymmetries of the mRGC outputs are still considerably smaller than those observed from human performance. We conclude that cone isomerizations, phototransduction, and the spatial filtering properties of mRGCs contribute to polar angle performance differences, but that a full account of these differences will entail additional contribution from cortical representations.

scholarly journals Temporal vision: measures, mechanisms and meaning

2021 ◽  
Vol 224 (15) ◽  
Author(s):  
Kristian Donner
Keyword(s):  
Visual Processing ◽  
Early Vision ◽  
Hidden Variable ◽  
Light Pulses ◽  
Temporal Properties ◽  
Trade Offs ◽  
Natural Vision ◽  
Retinal Photoreceptors ◽  
Temporal Aspects ◽  
Temporal Vision

ABSTRACT Time is largely a hidden variable in vision. It is the condition for seeing interesting things such as spatial forms and patterns, colours and movements in the external world, and yet is not meant to be noticed in itself. Temporal aspects of visual processing have received comparatively little attention in research. Temporal properties have been made explicit mainly in measurements of resolution and integration in simple tasks such as detection of spatially homogeneous flicker or light pulses of varying duration. Only through a mechanistic understanding of their basis in retinal photoreceptors and circuits can such measures guide modelling of natural vision in different species and illuminate functional and evolutionary trade-offs. Temporal vision research would benefit from bridging traditions that speak different languages. Towards that goal, I here review studies from the fields of human psychophysics, retinal physiology and neuroethology, with a focus on fundamental constraints set by early vision.

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