Dynamics of Attention in Depth: Evidence from Multi-Element Tracking

Perception ◽  
10.1068/p3432 ◽  
2002 ◽  
Vol 31 (12) ◽  
pp. 1415-1437 ◽  
Author(s):  
Lavanya Viswanathan ◽  
Ennio Mingolla
Keyword(s):  
Binocular Disparity ◽  
Spatial Separation ◽  
Three Dimensions ◽  
Moving Targets ◽  
Improve Performance ◽  
Frontoparallel Plane ◽  
Surface Information ◽  
Depth Cues ◽  
Planar Surfaces ◽  
Improved Performance

We examined the allocation of attention in depth using a multi-element tracking paradigm. Observers were required to track a predefined subset of from two to eight elements in displays containing up to sixteen identical moving elements. We first show that depth cues, such as binocular disparity and occlusion through T-junctions, improve performance in a multi-element tracking task in the case where element boundaries are allowed to intersect in the depiction of motion in a single frontoparallel plane. We also show that the allocation of attention across two perceptually distinguishable planar surfaces, either frontoparallel or receding at a slanting angle and defined by coplanar elements, is easier than allocation of attention within a single surface. The same result was not found when attention was required to be deployed across items of two-color populations rather than across items of a single color. Our results suggest that, when surface information does not suffice to distinguish between targets and distractors that are embedded in these surfaces, division of attention across two surfaces aids in tracking moving targets. A final experiment with populations of elements moving within distinct volumes produced similar results, suggesting that spatial separation in three dimensions, rather than confinement to surfaces as such, may explain the improved performance for the two-surface case.

scholarly journals PSVIII-35 Late-Breaking Abstract: Administration of an appeasing substance at castration improves performance of pre-conditioned beef crossbred steers

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 347-348
Author(s):  
Kelsey Schubach ◽  
Bruno I Cappellozza ◽  
Marcos Renato Burim ◽  
André Velasco ◽  
Fernando Sagrado ◽  
...  
Keyword(s):  
Feed Efficiency ◽  
Minimum Distance ◽  
Descriptive Analysis ◽  
Bos Indicus ◽  
Experimental Unit ◽  
Water Restriction ◽  
Improve Performance ◽  
Treatment Groups ◽  
Improved Performance ◽  
To Receive

Abstract Alternatives that alleviate stress-related responses and improve performance of the beef cattle herd are imperative and deserve further investigation. In previous trials, administration of the bovine appeasing substance (BAS) has improved performance of newly-weaned and feedlot received beef animals, as well as reduced the risk of dark, firm, and dry (DFD) cuts in carcass obtained from Bos indicus cattle. Therefore, this study was designed to evaluate the effects of BAS administration at castration on pre-conditioning performance of crossbred beef animals. On day 0, 390 crossbred Angus × Nellore animals were ranked by initial shrunk BW (255 ± 21.1 kg) and assigned to receive or not (CON) 5 mL/head of BAS (SecureCattle; Nutricorp, Araras, SP, Brazil) immediately before castration. From d 0 to 30, animals within treatments were maintained in 2 feedot pens with a minimum distance (300 m) to avoid contact between treatment groups and received a grass hay-based diet (70:30 roughage:concentrate ratio) ad libitum. On day 30, animals were individually weighed following 16 hours of feed and water restriction. Hence, a descriptive analysis was performed to evaluate pen dry matter intake (DMI) and feed efficiency (FE). Animal was considered the experimental unit and all data were analyzed using the PROC MIXED procedure of SAS (version 9.4; SAS Inst. Inc., Cary, NC). Bovine appeasing substance administration at castration improved ADG and BW change (P < 0.0001) compared with CON cohorts (0.983 vs. 1.155 kg/d and 29.5 vs. 34.6 kg for ADG and BW change, respectively). Total DMI was similar among treatments when reported as kg/d (6.70 vs. 6.75 kg) or % of BW (2.48 vs. 2.48%), whereas FE was dramatically improved in BAS-administered animals (146 vs. 172 g/kg for CON and BAS, respectively). In summary, BAS administration improved performance of crossbred beef animals for 30 days post-castration.

scholarly journals Abutting Objects Warp the Three-Dimensional Curvature of Modally Completing Surfaces

i-Perception ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 204166952090355 ◽  
Author(s):  
Peter U. Tse
Keyword(s):  
Visual Processing ◽  
Binocular Disparity ◽  
Three Dimensional ◽  
Surface Curvature ◽  
Amodal Completion ◽  
Three Dimensions ◽  
Curved Surfaces ◽  
Open Surface ◽  
Modal Completion

Binocular disparity can give rise to the perception of open surfaces or closed curved surfaces (volumes) that appear to vary smoothly across discrete depths. Here I build on my recent papers by providing examples where modally completing surfaces not only fill in from one depth layer’s visible contours to another layer’s visible contours within virtual contours in an analog manner, but where modally completing surface curvature is altered by the interpolation of an abutting object perceived to be connected to or embedded within that modally completing surface. Seemingly minor changes in such an abutting object can flip the interpretation of distal regions, for example, turning a distant edge (where a surface ends) into rim (where a surface bends to occlude itself) or turning an open surface into a closed one. In general, the interpolated modal surface appears to deform, warp, or bend in three-dimensions to accommodate the abutting object. These demonstrations cannot be easily explained by existing models of visual processing or modal completion and drive home the implausibility of localistic accounts of modal or amodal completion that are based, for example, solely on extending contours in space until they meet behind an occluder or in front of “pacmen.” These demonstrations place new constraints on the holistic surface and volume generation processes that construct our experience of a three-dimensional world of surfaces and objects under normal viewing conditions.

The Role of Target Salience in Crowding

Perception ◽  
10.1068/p5206 ◽  
2005 ◽  
Vol 34 (7) ◽  
pp. 823-833 ◽  
Author(s):  
Fatima M Felisberti ◽  
Joshua A Solomon ◽  
Michael J Morgan
Keyword(s):  
Individual Differences ◽  
Spatial Separation ◽  
Orientation Discrimination ◽  
Crowding Effect ◽  
Improved Performance

We studied ‘crowding’ in the parafovea using orientation identification of a Gabor target as the task, and flanking Gabors on an isoeccentric circle as distractors. Orientation-discrimination thresholds were raised by nearby flanking distractors. This crowding effect was increased by the number of distractors and decreased by the spatial separation between target and distractors. Crowding was greatest when the target was in the centre of the distractor array and smallest when the target was on the edge of the array. A cue indicating the position of the target improved performance when the position was otherwise unknown and the spatial separation between target and distractors was large, but the cue had no significant effect when separation was small. Increasing the contrast of the target relative to the distractors reduced crowding, but targets of smaller contrast than that of the distractors are even harder to identify than those of the same contrast. Putting the target and distractors in different depth planes decreased crowding for some observers, but there were qualitative individual differences. A large (say, 45°) difference in orientation between target and distractors caused the target to ‘pop out’ in a presence/absence task, despite the evidence from other studies that crowding is still found in these conditions. We conclude that salience has, at best, modest effects on crowding.

The Effect of Two-Dimensional and Three-Dimensional Distance on Apparent Motion

Perception ◽  
1983 ◽  
Vol 12 (3) ◽  
pp. 305-312 ◽  
Author(s):  
Kathleen Mutch ◽  
Isabel M Smith ◽  
Albert Yonas
Keyword(s):  
Motion Perception ◽  
Apparent Motion ◽  
Three Dimensional ◽  
Spatial Separation ◽  
Three Dimensions ◽  
Correspondence Problem ◽  
Two Dimensional ◽  
Motion Display ◽  
Specific Concern ◽  
Actual Depth

The problem of how the visual system matches corresponding inputs from one instant to the next to produce the perception of motion has been experimentally examined. The specific concern was whether this correspondence problem is solved prior to the interpretation of three-dimensional distance. Observers judged the degree of apparent motion between pairs of lights in a conflicting motion display. Spatial separation of the lights was varied in two and three dimensions in order to assess whether retinal distance, actual depth, or some combination of these provided critical information for correspondence. The results support Ullman's contention that only two-dimensional (retinal) distances are used in establishing correspondence in motion perception.

scholarly journals Stimulus Dependence of Disparity Coding in Primate Visual Area V4

2005 ◽  
Vol 93 (1) ◽  
pp. 620-626 ◽  
Author(s):  
Jay Hegdé ◽  
David C. Van Essen
Keyword(s):  
Binocular Disparity ◽  
Three Dimensional ◽  
Visual Area ◽  
Tuning Curves ◽  
Depth Cues ◽  
Area V4 ◽  
Random Dot Stereograms ◽  
Dimensional Shape ◽  
Visual Area V4 ◽  
Three Dimensional Shape

Disparity tuning in visual cortex has been shown using a variety of stimulus types that contain stereoscopic depth cues. It is not known whether different stimuli yield similar disparity tuning curves. We studied whether cells in visual area V4 of the macaque show similar disparity tuning profiles when the same set of disparity values were tested using bars or dynamic random dot stereograms, which are among the most commonly used stimuli for this purpose. In a majority of V4 cells (61%), the shape of the disparity tuning profile differed significantly for the two stimulus types. The two sets of stimuli yielded statistically indistinguishable disparity tuning profiles for only a small minority (6%) of V4 cells. These results indicate that disparity tuning in V4 is stimulus-dependent. Given the fact that bar stimuli contain two-dimensional (2-D) shape cues, and the random dot stereograms do not, our results also indicate that V4 cells represent 2-D shape and binocular disparity in an interdependent fashion, revealing an unexpected complexity in the analysis of depth and three-dimensional shape.

Effect of dietary energy content at different stages of growth on performance of intact male cattle

1976 ◽  
Vol 22 (2) ◽  
pp. 199-206 ◽  
Author(s):  
D. Levy ◽  
Z. Holzer ◽  
D. Ilan
Keyword(s):  
Energy Content ◽  
Live Weight ◽  
Carcass Composition ◽  
Dietary Energy ◽  
Constant Ratio ◽  
Improve Performance ◽  
Intact Male ◽  
Stages Of Growth ◽  
Improved Performance ◽  
Second Period

SUMMARYSix groups of Israeli-Friesian intact male calves were studied over growth periods of 200 to 300 kg, 300 to 400 kg, and 400 to 500 kg live weight. Different ratios (85: 15, 70: 30 and 50: 50) of concentrate to roughage were compared. Two groups received the same ratio (85: 15 or 70: 30) throughout the experiment. In the other groups, the proportion of concentrates was progressively increased or decreased.Live-weight gain in the first period ranged from 759 to 1013 g/day, i n the second period from 1095 to 1239 g/day and in the third period from 831 to 922 g/day. Overall rate of gain was highest in the groups receiving a constant ratio, regardless of the ratio used. Increasing the proportion of concentrates as the calves became heavier, which is common practice in Europe, did not improve performance and decreasing the proportion reduced performance. Only at 200 to 300 and at 400 to 500 kg live weight did a concentrate percentage higher than 50 result in improved performance.Dry-matter intake, relative to live weight, was higher with a ratio of 70: 30 than with one of 85: 15 or of 50: 50 in each period. Animals on a constant ratio of concentrates to roughage gave the most efficient conversion of feed energy to live weight.There were no significant differences in dressing percentage or in carcass composition.

scholarly journals Border-ownership-dependent tilt aftereffect for shape defined by binocular disparity and motion parallax

2018 ◽  
Author(s):  
Reuben Rideaux ◽  
William J Harrison
Keyword(s):  
Binocular Disparity ◽  
Motion Parallax ◽  
Neural Systems ◽  
Visual Object ◽  
Access To Information ◽  
Tilt Aftereffect ◽  
Critical Function ◽  
Depth Order ◽  
Depth Cues ◽  
Ground Segmentation

ABSTRACTDiscerning objects from their surrounds (i.e., figure-ground segmentation) in a way that guides adaptive behaviours is a fundamental task of the brain. Neurophysiological work has revealed a class of cells in the macaque visual cortex that may be ideally suited to support this neural computation: border-ownership cells (Zhou, Friedman, & von der Heydt, 2000). These orientation-tuned cells appear to respond conditionally to the borders of objects. A behavioural correlate supporting the existence of these cells in humans was demonstrated using two-dimensional luminance defined objects (von der Heydt, Macuda, & Qiu, 2005). However, objects in our natural visual environments are often signalled by complex cues, such as motion and depth order. Thus, for border-ownership systems to effectively support figure-ground segmentation and object depth ordering, they must have access to information from multiple depth cues with strict depth order selectivity. Here we measure in humans (of both sexes) border-ownership-dependent tilt aftereffects after adapting to figures defined by either motion parallax or binocular disparity. We find that both depth cues produce a tilt aftereffect that is selective for figure-ground depth order. Further, we find the effects of adaptation are transferable between cues, suggesting that these systems may combine depth cues to reduce uncertainty (Bülthoff & Mallot, 1988). These results suggest that border-ownership mechanisms have strict depth order selectivity and access to multiple depth cues that are jointly encoded, providing compelling psychophysical support for their role in figure-ground segmentation in natural visual environments.SIGNIFICANCE STATEMENTSegmenting a visual object from its surrounds is a critical function that may be supported by “border-ownership” neural systems that conditionally respond to object borders. Psychophysical work indicates these systems are sensitive to objects defined by luminance contrast. To effectively support figure-ground segmentation, however, neural systems supporting border-ownership must have access to information from multiple depth cues and depth order selectivity. We measured border-ownership-dependent tilt aftereffects to figures defined by either motion parallax or binocular disparity and found aftereffects for both depth cues. These effects were transferable between cues, but selective for figure-ground depth order. Our results suggest that the neural systems supporting figure-ground segmentation have strict depth order selectivity and access to multiple depth cues that are jointly encoded.

scholarly journals AN OVERVIEW OF TIME-DOMAIN COMPUTATIONAL METHODS FOR AEROELASTIC INSTABILITIES OF MULTI-STAGE COMPRESSOR

2020 ◽  
Vol 4 ◽  
pp. 114-127
Author(s):  
Mehdi Vahdati ◽  
Fanzhou Zhao ◽  
Prathiban Sureshkumar
Keyword(s):  
Time Domain ◽  
Forced Response ◽  
Imperial College ◽  
Aeroelastic Stability ◽  
Improve Performance ◽  
Campbell Diagram ◽  
The Past ◽  
Multi Stage ◽  
Improved Performance ◽  
Turbine Design

Modern gas turbine design continues to move towards improved performance, reduced weight and reduced cost. As turbomachinery blade aerofoils are thinned to improve performance and reduce weight, aeroelastic issues such as flutter, forced response and stall driven vibrations become more predominant. Moreover, as the use of blisks (blade-integrated-disks) with very low mechanical damping becomes more common in modern compressor designs, accurate prediction of compressor aeroelastic stability in a multi-row environment becomes vital. This paper presents a review of aeroelasticity research carried out at Rolls-Royce Vibration University Technology Centre (VUTC) at Imperial College over the past 20 years. The aim is to summarise the unusual aeroelastic issues observed in multi-stage compressors into one document so that it can be used by other researchers in the field. Blade passing forced response is not addressed here as their existence can be detected by a Campbell diagram. The results presented here are based on numerical methods but where possible data from experiments are used to verify the numerical findings.

scholarly journals Optimization of connected component labelling

2006 ◽  
Author(s):  
Richard Beare
Keyword(s):  
Connected Component ◽  
Improve Performance ◽  
Improved Performance

The report details some modifications made to the ITK {} in an attempt to improve performance. Some interesting observations were made during this process. A new filter using a different algorithm to perform the same function is also described and improved performance demonstrated.

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