176 research outputs found
Negative Results in Computer Vision: A Perspective
A negative result is when the outcome of an experiment or a model is not what
is expected or when a hypothesis does not hold. Despite being often overlooked
in the scientific community, negative results are results and they carry value.
While this topic has been extensively discussed in other fields such as social
sciences and biosciences, less attention has been paid to it in the computer
vision community. The unique characteristics of computer vision, particularly
its experimental aspect, call for a special treatment of this matter. In this
paper, I will address what makes negative results important, how they should be
disseminated and incentivized, and what lessons can be learned from cognitive
vision research in this regard. Further, I will discuss issues such as computer
vision and human vision interaction, experimental design and statistical
hypothesis testing, explanatory versus predictive modeling, performance
evaluation, model comparison, as well as computer vision research culture
Investigation of sequence processing: A cognitive and computational neuroscience perspective
Serial order processing or sequence processing underlies
many human activities such as speech, language, skill
learning, planning, problem-solving, etc. Investigating
the neural bases of sequence processing enables us to
understand serial order in cognition and also helps in
building intelligent devices. In this article, we review
various cognitive issues related to sequence processing
with examples. Experimental results that give evidence
for the involvement of various brain areas will be described.
Finally, a theoretical approach based on statistical
models and reinforcement learning paradigm is
presented. These theoretical ideas are useful for studying
sequence learning in a principled way. This article
also suggests a two-way process diagram integrating
experimentation (cognitive neuroscience) and theory/
computational modelling (computational neuroscience).
This integrated framework is useful not only in the present
study of serial order, but also for understanding
many cognitive processes
Active Sensing as Bayes-Optimal Sequential Decision Making
Sensory inference under conditions of uncertainty is a major problem in both
machine learning and computational neuroscience. An important but poorly
understood aspect of sensory processing is the role of active sensing. Here, we
present a Bayes-optimal inference and control framework for active sensing,
C-DAC (Context-Dependent Active Controller). Unlike previously proposed
algorithms that optimize abstract statistical objectives such as information
maximization (Infomax) [Butko & Movellan, 2010] or one-step look-ahead accuracy
[Najemnik & Geisler, 2005], our active sensing model directly minimizes a
combination of behavioral costs, such as temporal delay, response error, and
effort. We simulate these algorithms on a simple visual search task to
illustrate scenarios in which context-sensitivity is particularly beneficial
and optimization with respect to generic statistical objectives particularly
inadequate. Motivated by the geometric properties of the C-DAC policy, we
present both parametric and non-parametric approximations, which retain
context-sensitivity while significantly reducing computational complexity.
These approximations enable us to investigate the more complex problem
involving peripheral vision, and we notice that the difference between C-DAC
and statistical policies becomes even more evident in this scenario.Comment: Scheduled to appear in UAI 201
Selection strategies in gaze interaction
This thesis deals with selection strategies in gaze interaction, specifically for a context where gaze is the sole input modality for users with severe motor impairments. The goal has been to contribute to the subfield of assistive technology where gaze interaction is necessary for the user to achieve autonomous communication and environmental control.
From a theoretical point of view research has been done on the physiology of the gaze, eye tracking technology, and a taxonomy of existing selection strategies has been developed.
Empirically two overall approaches have been taken. Firstly, end-user research has been conducted through interviews and observation. The capabilities, requirements, and wants of the end-user have been explored. Secondly, several applications have been developed to explore the selection strategy of single stroke gaze gestures (SSGG) and aspects of complex gaze gestures.
The main finding is that single stroke gaze gestures can successfully be used as a selection strategy. Some of the features of SSGG are: That horizontal single stroke gaze gestures are faster than vertical single stroke gaze gestures; That there is a significant difference in completion time depending on gesture length; That single stroke gaze gestures can be completed without visual feedback; That gaze tracking equipment has a significant effect on the completion times and error rates of single stroke gaze gestures; That there is not a significantly greater chance of making selection errors with single stroke gaze gestures compared with dwell selection.
The overall conclusion is that the future of gaze interaction should focus on developing multi-modal interactions for mono-modal input
Constructing the space of visual attention
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Page 180 blank. Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 168-171).This thesis explores the nature of a human experience in space through a primary inquiry into vision. This inquiry begins by questioning the existing methods and instruments employed to capture and represent a human experience of space. While existing qualitative and quantitative methods and instruments -- from "subjective" interviews to "objective" photographic documentation -- may lead to insight in the study of a human experience in space, we argue that they are inherently limited with respect to physiological realities. As one moves about the world, one believes to see the world as continuous and fully resolved. However, this is not how human vision is currently understood to function on a physiological level. If we want to understand how humans visually construct a space, then we must examine patterns of visual attention on a physiological level. In order to inquire into patterns of visual attention in three dimensional space, we need to develop new instruments and new methods of representation. The instruments we require, directly address the physiological realities of vision, and the methods of representation seek to situate the human subject within a space of their own construction. In order to achieve this goal we have developed PUPIL, a custom set of hardware and software instruments, that capture the subject's eye movements. Using PUPIL, we have conducted a series of trials from proof of concept -- demonstrating the capabilities of our instruments -- to critical inquiry of the relationship between a human subject and a space. We have developed software to visualize this unique spatial experience, and have posed open questions based on the initial findings of our trials. This thesis aims to contribute to spatial design disciplines, by providing a new way to capture and represent a human experience of space.by Moritz Philipp Kassner [and] William Rhoades Patera.S.M
The plasticity of human saccadic eye movements
The central purpose of this research has been to examine the possibility of the plasticity of individual saccadic parameters and to identify their patterns of covariation. Experiments using trial-by-trial feedback or continuous on-going feedback methods demonstrated that the saccadic generator can prolong the duration of a saccade above normal levels. However, slowed peak velocities were only evident with continuous feedback. The results showed that although continuous feedback was a more effective method for inducing modifications of saccade trajectories, the effects of trial-by-trial feedback schedules were enhanced by distributing the training over several days. The instructions to produce slow saccades caused a 'staircase' pattern of eye movements in which a continuous sequence of hypometric saccades was manifested. These saccades had latencies 400-600 msecs longer than normal visually controlled eye movements. Detailed measurements (chapter 4) of the latencies of the saccadic components indicated that each component was programmed independently. In chapter 5 the Gurevich claim that a saccade velocity depends only on the spatial magnitude of the saccade was tested by measuring saccades of equivalent amplitudes to targets which varied in movement duration and velocity. The accuracy of saccades but not their peak velocities or durations was sensitive to manipulations in the temporal characteristics of the target. Experiments in chapter 6 showed that the use of spatial signals in the aiming of a saccade can be systematically controlled. When subjects were trained for several days in a visual discrimination task the accuracy of the initial saccadic movement increased over time. The results of these experiments seriously question the Young and Stark (1963b) ballistic model and other formulations (Westheimer, 1954b, 1973; Yarbus, 1967) which assume that the saccadic system operates according to stereotyped mechanisms
On Multifractal Structure in Non-Representational Art
Multifractal analysis techniques are applied to patterns in several abstract
expressionist artworks, paintined by various artists. The analysis is carried
out on two distinct types of structures: the physical patterns formed by a
specific color (``blobs''), as well as patterns formed by the luminance
gradient between adjacent colors (``edges''). It is found that the analysis
method applied to ``blobs'' cannot distinguish between artists of the same
movement, yielding a multifractal spectrum of dimensions between about 1.5-1.8.
The method can distinguish between different types of images, however, as
demonstrated by studying a radically different type of art. The data suggests
that the ``edge'' method can distinguish between artists in the same movement,
and is proposed to represent a toy model of visual discrimination. A ``fractal
reconstruction'' analysis technique is also applied to the images, in order to
determine whether or not a specific signature can be extracted which might
serve as a type of fingerprint for the movement. However, these results are
vague and no direct conclusions may be drawn.Comment: 53 pp LaTeX, 10 figures (ps/eps
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