The Golf-Ball Illusion: Evidence for Top-down Processing in Weight Perception

Perception ◽  
1998 ◽  
Vol 27 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Robert R Ellis ◽  
Susan J Lederman
Keyword(s):  
Weight Perception ◽  
Equal Weight ◽  
Top Down ◽  
Low Level ◽  
Weight Difference ◽  
Sensory Cue ◽  
Weight Illusion ◽  
Primary Contribution ◽  
Weight Illusions

Theories of weight illusions have traditionally emphasised either the primary contribution of low-level sensory cues or the role of expectation based on knowledge and past experience. Current models of weight illusions lean quite strongly towards sensory-based interpretations. The current experiment raises a problem for such approaches by generating a weight illusion that is difficult to explain other than by the participants' knowledge. Golfers (who expect a weight difference between ball types) reliably judged practice golf balls to weigh more than real golf balls of the same weight. In contrast, non-golfers (who expect no weight difference between ball types) judged practice and real balls of equal weight to weigh the same. Furthermore, within the group of golfers, those who expected the weights of the two ball types to be the most discrepant prior to lifting tended to report the strongest illusions subsequent to lifting. Because there is no low-level sensory cue between ball types that on its own would signal a weight difference, the current finding suggests that there is a top-down component to weight perception that is based on experience with specific objects.

scholarly journals Effects of TMS over the anterior intraparietal area on anticipatory fingertip force scaling and the size-weight illusion

2020 ◽  
Author(s):  
Vonne van Polanen ◽  
Gavin Buckingham ◽  
Marco Davare
Keyword(s):  
Primary Motor Cortex ◽  
Weight Perception ◽  
Control Area ◽  
Equal Weight ◽  
Small Object ◽  
Object Size ◽  
Neural Underpinnings ◽  
Weight Illusion ◽  
Force Scaling

ABSTRACTIn skilled object lifting, fingertip forces need to be carefully scaled to object weight, which can be inferred from object properties, such as size or material. This anticipatory force scaling ensures smooth and efficient lifting movements. However, even with accurate motor plans, weight perception can still be biased. In the size-weight illusion, objects of different size but equal weight are perceived to differ in heaviness, with the small object perceived to be heavier than the large object. The neural underpinnings of the size-weight illusion and anticipatory force scaling to object size are largely unknown. In this study, we hypothesized a possible role of the anterior intraparietal cortex (aIPS) in predictive force scaling and the size-weight illusion, which we investigated by applying continuous theta burst stimulation (cTBS) prior to participants lifting objects designed to induce the size-weight illusion. Participants received cTBS over aIPS, the primary motor cortex (control area), or sham stimulation. We found no evidence that aIPS stimulation affected the size-weight illusion. Small effects were, however, found on anticipatory force scaling, where grip force was less tuned to object size during initial lifts. These findings suggest that, while aIPS might be peripherally involved in sensorimotor prediction, other brain areas underpin the processes that mediate the size-weight illusion.

Virtual Weight Illusion: Weight Perception of Virtual Objects Using Weight Illusions

2021 ◽  
Author(s):  
Akihiro Maehigashi ◽  
Akira Sasada ◽  
Miki Matsumuro ◽  
Fumihisa Shibata ◽  
Asako Kimura ◽  
...  
Keyword(s):  
Weight Perception ◽  
Virtual Objects ◽  
Weight Illusion ◽  
Weight Illusions

scholarly journals Investigating the Role of Haptic and Visual Perception in the Material-Weight Illusion

2020 ◽  
Author(s):  
Caitlin Elisabeth Naylor ◽  
Michael Proulx ◽  
Gavin Buckingham
Keyword(s):  
Virtual Reality ◽  
Visual Perception ◽  
Prior Experience ◽  
Visual Material ◽  
Optimal Integration ◽  
Weight Illusion ◽  
Weight Illusions

Weight illusions provide a compelling demonstration that prior experience affects perception. Here we investigated how the expectation-inducing modality affected the Material-Weight Illusion (MWI), where dense-looking objects feel lighter than less dense-looking objects. Participants lifted equally-weighted polystyrene, cork, and granite cubes whilst viewing computer-generated images of the cubes in virtual reality (VR). The representation of the object in VR was manipulated to create four illusion-inducing sensory conditions: visual differences only, haptic differences only, congruent visual-haptic differences, and incongruent visual-haptic material differences. Although an MWI was induced in all conditions, whereby the polystyrene object was reported to feel heavier than the granite object, the strength of the MWI differed across conditions, with haptic material cues having a stronger influence on perceived heaviness than visual material cues. These results are consistent with optimal integration theories of multi-modal perception, highlighting that perception reflects individual cues’ reliability and relevance in specific contexts.

scholarly journals You won’t believe what this guy is doing with the potato: The ObjAct stimulus-set depicting human actions on congruent and incongruent objects

2021 ◽  
Author(s):  
Yarden Shir ◽  
Naphtali Abudarham ◽  
Liad Mudrik
Keyword(s):  
Visual Complexity ◽  
Real Life ◽  
Top Down ◽  
Object Processing ◽  
Human Actions ◽  
Low Level ◽  
Stimulus Set ◽  
Characterization Procedure ◽  
Online Sources

AbstractPerception famously involves both bottom-up and top-down processes. The latter are influenced by our previous knowledge and expectations about the world. In recent years, many studies have focused on the role of expectations in perception in general, and in object processing in particular. Yet studying this question is not an easy feat, requiring—among other things—the creation and validation of appropriate stimuli. Here, we introduce the ObjAct stimulus-set of free-to-use, highly controlled real-life scenes, on which critical objects are pasted. All scenes depict human agents performing an action with an object that is either congruent or incongruent with the action. The focus on human actions yields highly constraining contexts, strengthening congruency effects. The stimuli were analyzed for low-level properties, using the SHINE toolbox to control for luminance and contrast, and using a deep convolutional neural network to mimic V1 processing and potentially discover other low-level factors that might differ between congruent and incongruent scenes. Two online validation studies (N = 500) were also conducted to assess the congruency manipulation and collect additional ratings of our images (e.g., arousal, likeability, visual complexity). We also provide full descriptions of the online sources from which all images were taken, as well as verbal descriptions of their content. Taken together, this extensive validation and characterization procedure makes the ObjAct stimulus-set highly informative and easy to use for future researchers in multiple fields, from object and scene processing, through top-down contextual effects, to the study of actions.

scholarly journals Perceiving and acting upon weight illusions in the absence of somatosensory information

2016 ◽  
Vol 115 (4) ◽  
pp. 1946-1953 ◽  
Author(s):  
Gavin Buckingham ◽  
Elizabeth Evgenia Michelakakis ◽  
Jonathan Cole
Keyword(s):  
Material Properties ◽  
Weight Perception ◽  
Visual Appearance ◽  
Fingertip Force ◽  
Object Weight ◽  
Somatosensory Information ◽  
Novel Objects ◽  
Weight Illusion ◽  
Fingertip Forces ◽  
Weight Illusions

When lifting novel objects, individuals' fingertip forces are influenced by a variety of cues such as volume and apparent material. This means that heavy-looking objects tend to be lifted with more force than lighter-looking objects, even when they weigh the same amount as one another. Expectations about object weight based on visual appearance also influence how heavy an object feels when it is lifted. For instance, in the “size-weight illusion,” small objects feel heavier than equally weighted large objects. Similarly, in the “material-weight illusion,” objects that seem to be made from light-looking materials feel heavier than objects of the same weight that appear to be made from heavy-looking materials. In this study, we investigated these perceptual and sensorimotor effects in IW, an individual with peripheral deafferentation (i.e., a loss of tactile and proprioception feedback). We examined his perceptions of heaviness and fingertip force application over repeated lifts of objects that varied in size or material properties. Despite being able to report real weight differences, IW did not appear to experience the size- or material-weight illusions. Furthermore, he showed no evidence of sensorimotor prediction based on size and material cues. The results are discussed in the context of forward models and their possible influence on weight perception and fingertip force control.

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

ROLE OF LIPID PROFILE IN OVARIAN CARCINOMA PATIENTS

2019 ◽  
Vol 3 (8) ◽  
Author(s):  
Dr. Manisha ◽  
Dr. Ruchi Jindal
Keyword(s):  
Ovarian Cancer ◽  
Lipid Profile ◽  
Cancer Patients ◽  
Ovarian Tumor ◽  
Ovarian Cancer Risk ◽  
Low Level ◽  
Medical College ◽  
Group I ◽  
History Of

Background: The term "ovarian cancer" includes several different types of cancer that  arise from cells of the ovary, most commonly, tumors arise from the epithelium or lining cells of the ovary.  Ovarian cancer risk is positively associated with higher consumption of dietary cholesterol and eggs, and inversely associated with a higher intake of vegetables. High consumption of fats may increase circulating estrogen levels, thus increasing the possibility of cell damage and proliferation that is responsible for cancerous growth. Material & Methods: The present study was conducted at Geetanjali Medical College and Hospital, Udaipur (Rajasthan). Total  100 cases (females) attending the obstetrics and gynecology department for some gynecological and other problem  were selected for this study between the age of 40-60 years, who were attending cancer centre at GEETANJALI MEDICAL COLLEGE AND  HOSPITAL, Udaipur (Rajasthan).                GROUP I: - It consisted of healthy females control subjects (n=50) .By routine examination and tests, we ensured that all the subjects were healthy and there were no signs and symptoms or history of ovarian tumor and diseases GROUP II: - It consisted of ovarian cancer females subjects (n=50) with a history of ovarian tumor. Results:   Higher level of cholesterol, LDL, VLDL and low level of HDL are found in ovarian cancer patients. Conclusion: The present study we highlights the importance and role of serum lipid profile in diagnosis, prognosis and recurrence of the disease. The study shows that serum level of cholesterol, LDL, VLDL was elevated in  patients of ovarian cancer while low level of HDL are found in ovarian cancer patients. Key words: lipid profile, ovarian cancer.

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