Search results for "Special Relativity"
showing 10 items of 60 documents
Traffic Flow Variables Estimation: An Automated Procedure Based on Moving Observer Method. Potential Application for Autonomous Vehicles
2019
Abstract The estimation of traffic flow variables (flow, space mean speed and density) plays a fundamental role in highways planning and designing, as well as in traffic control strategies. Moving Observer Method (MOM) allows traffic surveys in a road, or in a road network. This paper proposes a novel automated procedure, called MOM-AP based on Moving Observer Method and Digital Image Processing (DIP) Technique able to automatically detect (without human observers) and calculate flow q, space mean speed vs and density k in case of stationary and homogeneous traffic conditions. In order to evaluate how reliable is the MOM-AP, an experiment has been carried out in a segment of one two-lane si…
Empiricism and Relationism Intertwined: Hume and Einstein’s Special Theory of Relativity
2016
Einstein acknowledged that his reading of Hume influenced the development of his special theory of relativity. In this article, I juxtapose Hume’s philosophy with Einstein’s philosophical analysis related to his special relativity. I argue that there are two common points to be found in their writings, namely an empiricist theory of ideas and concepts, and a relationist ontology regarding space and time. The main thesis of this article is that these two points are intertwined in Hume and Einstein.
Size invariance in visual number discrimination
1991
This study deals with the observer's ability to discriminate the numerosity of two random dot-patterns irrespective of their relative size. One of these two patterns was a reference one that was always composed of 32 dots randomly distributed within a K x K invisible square window (K = 1.92 degrees). The second one was the test pattern with one of the five magnifications (K = 0.64 degrees, 1.28 degrees, 1.92 degrees, 2.56 degrees, 3.20 degrees) and the relative number of dots varied on 11 levels (N = -15, -12, -9, -6, -3, 0, 3, 6, 9, 12, or 15 dots). The observer's task was to indicate which of the two patterns contained more dots. The results show that the stimulus size, as an irrelevant s…
The shape of personal space.
2019
The notion of a personal space surrounding one's ego-center is time-honored. However, few attempts have been made to measure the shape of this space. With increasing use of virtual environments, the question has arisen if real-world aspects, such as gender-effects or the shape of personal space, translate to virtual setups. We conducted two experiments, one with real people matched according to body height and level of acquaintance in a large laboratory setting, and one where subjects faced a virtual character, likewise matched to their body height. The first experiment also used a mannequin in place of the second human observer. The second experiment additionally manipulated the perspectiv…
A Slippery Slope: Estimated Slant of Hills Increases with Distance
2014
The slopes of hills tend to be greatly overestimated. Previous studies have found that slope estimates are significantly greater when estimated verbally than with a proprioceptive measure. It has yet to be determined whether these estimates are made for the entire extent of the slope, or whether the estimates in closest proximity are estimated using a different process. Since some parietal cortex neurons respond differently to objects within arm's reach, short-distance slope estimation may utilize these or analogous neurons. Alternatively, greater implied effort might make longer slopes seem steeper. We determined that both verbal and proprioceptive reports of slope are overestimates that …
Effects of symmetry, texture, and monocular viewing on geographical slant estimation.
2018
Hills often appear to be steeper than they are. The unusual magnitude of this error has prompted extensive experimentation. The judgment mode, such as verbal vs. action-based measures, the state of the observer - whether exhausted or well rested - all can influence perceived geographical slant. We hold that slant perception is inherently shaky as soon as the slope in question is no longer palpable, that is if it is outside our personal space. To make this point, we have added symmetry, texture, and depression to the list of factors that might modulate slant perception. When the frontal slope of a hill is to be judged, it appears steeper when the side slopes are steep. We have used model hil…
Role of sensorimotor areas in early detection of motor errors: An EEG and TMS study
2019
Abstract Action execution is prone to errors and, while engaged in interaction, our brain is tuned to detect deviations from what one expects from other’s action. Prior research has shown that Event-Related-Potentials (ERPs) are specifically modulated by the observation of action mistakes interfering with goal achievement. However, in complex and modular actions, embedded motor errors do not necessarily produce an immediate effect on the global goal. Here we dissociate embedded motor goals from global action goals by asking subjects to observe familiar but untrained knotting actions. During knotting an embedded motor error (i.e. the rope is inserted top-down instead of bottom-up during the …
Differentiating the differential rotation effect.
2011
As an observer views a picture from different viewing angles, objects in the picture appear to maintain their orientation relative to the observer. For instance, the eyes of a portrait appear to follow the observer as he or she views the image from different angles. We have explored this rotation effect, often called the Mona Lisa effect. We report three experiments that used portrait photographs to test variations of the Mona Lisa effect. The first experiment introduced picture displacements relative to the observer in directions beyond the horizontal plane. The Mona Lisa effect remained robust for vertical and/or diagonal observer displacements. The experiment also included conditions in …
For the mind's eye the world is two-dimensional.
2010
The nature of visual mental images is a topic that has puzzled neuroscientists, psychologists, and philosophers alike. On the one hand, mental images might preserve the 3-D properties of our perceptual world. On the other hand, they might be akin to 2-D pictures, such as photographs, paintings, or drawings. In the present study, 16 observers judged where real objects (Experiment 1) or photographs thereof (Experiment 2) were pointing. Both experiments contained a perception condition and an imagery condition. In Experiment 1, there was a significant difference between the pointing errors in the perception and the imagery conditions, whereas there was no such difference in Experiment 2. In im…
Allocentric time-to-contact and the devastating effect of perspective
2014
AbstractWith regard to impending object–object collisions, observers may use different sources of information to judge time to contact (tC). We introduced changes of the observer’s vantage point to test among three sets of hypotheses: (1) Observers may use a distance-divided-by-velocity algorithm or, alternatively, elaborated τ-formulae, all of which give exact tC information; (2) observers may use simple τ-formulae (i.e., formulae of the type: visual angle divided by its own first temporal derivative); (3) observers may capitalize on non-τ variables. Hypotheses (2) and (3) imply specific patterns of errors. We presented animated, impending collisions between a moving object and a stationar…