Visual illusions affect planning but not control

It has been suggested that goal-directed actions performed under full vision are immune to certain visual illusions, while movements relying on perception-based visual information are deceived by them (Milner & Goodale, 1995). Consequently, pointing movements should be deceived by visual illusions when a delay is introduced (memory demands) or when antipointing (spatial imagery) is required. In 2 experiments, participants performed either propointing or antipointing movements to different versions of the Müller-Lyer illusion in 2 vision conditions (open-loop vs. delay). Apart from open-loop propointing, all conditions should rely on perceptual processing and should therefore yield similarly illusion effects. While we observed illusion effects in all conditions, their magnitude varied in unexpected ways. Most surprisingly, introducing a delay seemed to reduce illusion effects in antipointing. We show that this decrease can be explained by the fact that pointing after delay is less responsive to physical size changes. After correcting for this, illusion effects in antipointing were similar in both vision conditions but still twice as large as in the delayed propointing task. Our findings highlight the necessity of employing a correction procedure when comparing illusion effects across tasks and do not conform well to the predictions derived from the perception-action model.

Visual illusions occur around us all the time, which present in nature and appear when you least expect it. It is well known that visual illusions can have a dramatic effect upon our visual perception of an object 's size and position. However, whether visual illusions have a similar influence on visual guided action or not, it remains the subject of much debate. The purpose of this study is to explore whether the visual information used to identify and categorize an object would be similar to the visual information used to plan and control visually guided movements directed toward that object. The outcome of this study will be helpful for designers to understand our visual information system and apply that knowledge to the design practice. In order to achieve the purpose of this study mentioned above, three visual illusions as the experiment's apparatus are applied to examine the relative effect of visual illusions on both the visual perceived center of an object and the position of a grasp on that object when a balanced lift is required. The results of the experiment show that (1) Illusions influence both the perceived and the grasped estimates of the center position, but the grasp center is more veridical; (2) Judd-illusion, one of the three visual illusions, has a bigger degree of effect than two other illusions on both the perceived and the grasped estimates of the center position; (3) By providing the participants with a mean to guide their visual perception of these illusions, the errors from the estimation of the center position can be significantly reduced.

Although the effect of visual illusions on overt actions has been an area of keen interest in motor performance, no study has yet examined whether illusions have similar or different effects on overt and imagined movements. Two experiments were conducted that compared the effects of an orientation illusion on an overt posture selection task and an imagined posture selection task. In Experiment 1 subjects were given a choice of grasping a bar with the thumb on the left side or right side of the bar. In Experiment 2 subjects were instructed to only imagine grasping the bar while remaining motionless. Subjects then reported which side of the bar their thumb had been placed in imagined grasping. Both the overt selection and imagined selection tasks were found to be sensitive to the orientation illusion, suggesting that similar visual information is used for overt and imagined movements, with both being sensitive to an orientation illusion. The results are discussed in terms of the visual processing and representation of real and imagined actions.

This study is about the expression types and characteristics of Trompe l`oeil in modern fashion. The study defines the concept of Trompe l`oeil, examines the Trompe l`oeil in the surrealist works from which the Trompe l`oeil derives from, and analyzes the works that have emerged since 2000. The study used a collection of magazines such as Vogue, Gap, Fashion News, and the Internet. According to the findings, the expression types of Trompe l`oeil in modern fashion were seen in the human body, the wearing style, the details, and accessory effects of clothes. The modern fashion design using the Trompe l`oeil based on such external expressions was characterized by the following: first, the fashion design destroyed the concept of common sense and expressed the purity of the human spirit by revealing the human body hidden in clothes from the combination of clothes and the human body with surrealism. Second, the details or accessories of clothes were printed or painted as if they existed. Pleasure was expressed by applying Trompe l`oeil to the wearing methods and forms of clothes through the optical illusion of materials or colors. Third, the effects of an optical illusion were displayed by transforming and distorting the wearing style and reversing the front, back, exterior and interior of clothes; this optical illusion characterized the deconstruction expressed through the transformation of ideas.

To live independently, older adults (OA) need to properly integrate sensory information from their environment to perform the activities of daily living (ADL). If a reliable relation between MSI and the performance of ADL can be shown, a measure of MSI may be used as an early diagnostic/predictive tool for ADL problems in individual OA. This thesis aims to develop this tool to allow clinicians developing personalized interventions to help OA maintain their quality of life and stay independent. We showed that aging influences sensory integration. We used an interception task with disappearing targets moving downwards on a screen while the background was moving horizontally creating an illusion of motion of the target. We added dual tasks to the baseline perturbing the proprioceptive and vestibular inputs or increasing the cognitive load. Overall, OA without any problem to perform ADL tend to have a larger effect of the illusion as compared to YA. However, OA with a range of ADL difficulties showed three different patterns of illusion effect: a (large) illusion effect (‘over integration’ pattern), a reverse illusion effect (‘dragged by the background’ pattern) and no illusion effect (‘minimal use of visual information’ pattern). We developed a transitional model of the aging process happening in our task. Our task alone can predict the results of ADL-related clinical pretests measuring issues in sensorimotor systems that contribute to postural control, ADL issues, functional change of transitional movements, survival rates and life expectancy. This thesis was a first step towards the development of a clinical tool that could assist the diagnosis of MSI issues in OA and predict the onset of problems in ADL.

Another Look at the Visual Illusion:The Effect of Muller-Lyer Illusion on Perception and Action

Visual size illusions have been shown to affect perceived object size but not the aperture of the hand when reaching to those same objects. Thus, vision for perception is said to be dissociated from vision for action. The present study examines the effect of visual-position and visual-shape illusions on both the visually perceived center of an object and the position of a grasp on that object when a balanced lift is required. The results for both experiments show that although the illusions influence both the perceived and the grasped estimates of the center position, the grasp position is more veridical. This partial dissociation is discussed in terms of its implications for streams of visual processing.

Mirror-induced visual illusion obtained through mirror therapy is widely used to facilitate motor recovery after stroke. Activation of primary motor cortex (M1) ipsilateral to the moving limb has been reported during mirror-induced visual illusion. However, the mechanism through which the mirror illusion elicits motor execution processes without movements observed in the mirrored limb remains unclear. This study aims to review evidence based on brain imaging studies for testing the hypothesis that neural processes associated with kinaesthetic motor imagery are attributed to ipsilateral M1 activation. Four electronic databases were searched. Studies on functional brain imaging, investigating the instant effects of mirror-induced visual illusion among stroke survivors and healthy participants were included. Thirty-five studies engaging 78 stroke survivors and 396 healthy participants were reviewed. Results of functional brain scans (n = 20) indicated that half of the studies (n = 10, 50%) reported significant changes in the activation of ipsilateral M1, which mediates motor preparation and execution. Other common neural substrates included primary somatosensory cortex (45%, kinaesthesia), precuneus (40%, image generation and self-processing operations) and cerebellum (20%, motor control). Similar patterns of ipsilateral M1 activations were observed in the two groups. These neural substrates mediated the generation, maintenance, and manipulation of motor-related images, which were the key processes in kinaesthetic motor imagery. Relationships in terms of shared neural substrates and mental processes between mirror-induced visual illusion and kinaesthetic motor imagery generate new evidence on the role of the latter in mirror therapy. Future studies should investigate the imagery processes in illusion training for post-stroke patients.

Visual illusions affect both movement planning and on-line control: A multiple cue position on bias and goal-directed action

ABSTRACTPreviously, we have shown that discrete and continuous rapid aiming tasks are governed by distinct visuomotor control mechanisms by assessing the combined visual illusion effects on the perceived and effective index of difficulty (ID). All participants were perceptually biased by the combined visual illusion before they performed the rapid aiming tasks. In the current study, the authors manipulated the order of performing perceptual and motor tasks to examine whether perceptual or motor experience with the illusory visual target would influence the subsequent perceived and effective ID in discrete and continuous tapping tasks. The results supported our hypothesis showing that perceptual experience with the illusory visual target in the discrete condition reduced the effective ID in the subsequent discrete tapping task, and motor experience with the illusory visual target in the continuous condition reduced the illusion effects on the perceived ID in the subsequent perceptual judgment task. The study demonstrates the coinfluence of perception and action, and suggests that perception and action influence one another with different magnitude depending on the spatial frame of reference used to perform the perceptuomotor task.

Abstract. Thermodynamic and dynamic sea ice thickness processes are affected by differing mechanisms in a changing climate. Independent observational datasets of each are essential for model validation and accurate projections of future sea ice conditions. Here, we present a monthly, Arctic-basin-wide, and 25 km resolution Eulerian estimation of thermodynamic and dynamic effects on wintertime sea ice thickness from 2010–2021. Estimates of thermodynamic growth rate are determined by coupling passive microwave-retrieved snow–ice interface temperatures to a simple sea ice thermodynamic model, total growth is calculated from a weekly Alfred Wegener Institute (AWI) European Space Agency (ESA) CryoSat-2 and Soil Moisture and Ocean Salinity (SMOS) combination product (CS2SMOS), and dynamic effects are calculated as their difference. The dynamic effects are further separated into advection and residual effects using a sea ice motion dataset. Our results show new detail in these fields and, when summed to a basin-wide or regional scale, are in line with previous studies. Across the Arctic, dynamic effects are negative and about one-fourth the magnitude of thermodynamic growth. Thermodynamic growth varies from less than 0.1 m per month in the central Arctic to greater than 0.3 m per month in the seasonal ice zones. High positive dynamic effects of greater than 0.1 m per month, twice that of thermodynamic growth or more in some areas, are found north of the Canadian Arctic Archipelago, where the Transpolar Drift and Beaufort Gyre deposit ice. Strong negative dynamic effects of less than −0.2 m per month are found where the Transpolar Drift originates, nearly equal to and opposite the thermodynamic effects in these regions. Monthly results compare well with a recent study of the dynamic and thermodynamic effects on sea ice thickness along the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) drift track during the winter of 2019–2020. Couplets of deformation and advection effects with opposite signs are common across the Arctic, with positive advection effects and negative deformation effects found in the Beaufort Sea and negative advection effects and positive deformation effects found in most other regions. The seasonal cycle shows residual deformation effects and overall dynamic effects increasing as the winter season progresses.

The Effect of Visual Illusion and Attention Instructions on Golf Putting Performance and Impact Learning in Children

Despite both domestic and overseas markets are depressed due to the global financial crisis - the apparel industry is no exception, the market for the outdoor wears including the hiking ones has been recording a high growth rate, making the outdoor wear a high growth industry. The purpose of this study was to provide some basic data useful to our outdoor businesses to help them respond to consumers` needs in the rapidly growing outdoor markets. For silhouettes, the point was given primarily to the oblique cutting to have it follow the human body curves and thereby, look natural and slim. Another point was given to the color schemes along the cutting lines, so that an effect of optical illusion could be created to make the wears look slim making use of lines and colors. On the other hand, in consideration of the rapidly changing weather conditions during hiking, the details were designed practically by setting appropriate hip lengths, using attachable/detachable hoods as well as applying the Velcro & rubber band-type set-in sleeves for the tail edges. As discussed above, the researcher analyzed the design elements for the outdoor wears and developed some sensuous designs meeting consumers` needs to help our outdoor wear businesses to expand their target base, while awakening them of the importance of the outdoor fashion.

<p class="MsoNormal" style="margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: Calibri, sans-serif; color: rgb(0, 0, 0); text-align: justify;"><span style="font-family: &quot;Times New Roman&quot;, serif;">Geometric-Optical Art yields an awareness of a mismatch of geometrical properties between an item in object space and its associated perception (Westheimer, 2008). Inspired by Geometric-Optical Art and the concept of perception, the goals of creating this design research were to a) utilize fabric color and textures to express the visual effect of optical illusions, and b) determine the feasibility of creating Optical Art motifs with textiles and garment patterns for making creative silhouettes. The whole design process was divided into three steps. The first step was creating motif patterns for laser cutting and digital textile print. The second step of the design process was textile manipulation, which mainly combined inspirational images and the created motif in the first step with the researched fabric modification methods to transform two-dimensional planar patterns into three-dimensional stereoscopic texture effects. The third step was implementation by the method of 2D-3D-2D.<o:p></o:p></span>

Visual illusions allow for strong tests of perceptual functioning. Perceptual impairments can produce superior task performance on certain tasks (i.e., more veridical perception), thereby avoiding generalized deficit confounds while tapping mechanisms that are largely outside of conscious control. Using a task based on the Ebbinghaus illusion, a perceptual phenomenon where the perceived size of a central target object is affected by the size of surrounding inducers, we tested hypotheses related to visual integration in deaf (n = 31) and hearing (n = 34) patients with schizophrenia. In past studies, psychiatrically healthy samples displayed increased visual integration relative to schizophrenia samples and thus were less able to correctly judge target sizes. Deafness, and especially the use of sign language, leads to heightened sensitivity to peripheral visual cues and increased sensitivity to visual context. Therefore, relative to hearing subjects, deaf subjects were expected to display increased context sensitivity (ie, a more normal illusion effect as evidenced by a decreased ability to correctly judge central target sizes). Confirming the hypothesis, deaf signers were significantly more sensitive to the illusion than nonsigning hearing patients. Moreover, an earlier age of sign language acquisition, higher levels of linguistic ability, and shorter illness duration were significantly related to increased context sensitivity. As predicted, disorganization was associated with reduced context sensitivity for all subjects. The primary implications of these data are that perceptual organization impairment in schizophrenia is plastic and that it is related to a broader failure in coordinating cognitive activity.