Visial Fields - Research Paper Example

? Visual Fields Visual Fields Introduction Visual fields are generally referred to as fields of view, and can be defined as the spatial array of the visual sensations available for the observations in psychological experiments. Therefore, the field of view is the physical objects, and the sources of light found in the outside world, which impinge on the retina. The field of view consists of everything at a particular given time period, causes light to fall on the retina. These physical objects are referred to as inputs, which are processed by the visual system, and calculate the visual field as the output. Visual spatial resolution is influenced by variables such as optics, and neuronal filters within the visual cortex. Much information is not available how it is affected by the resolving power of attention, and a lot of confusion exists in visual neuroscience, and psychology in the usage of the terms; visual field, field of vision, stimulus field, and topographical brain maps. In order for a person to receive information from the environment, they make use of the sense such as eyes, nose, and ear. Most objects and occurrences of the natural environment produce light and sound energies, which are complimenting and are detectable by specialized visual and auditory sense organs. There exists certain locations in the human visual fields, such as north, south, east, and west, which perform better in the visual search, plus either audio sine or square wave. Performance in many visual discrimination abilities are better along the horizontal as compared to the vertical meridian, also known as Horizontal vertical Anisotropy(HVA), and also along the lower than upper vertical meridian, known as vertical meridian Asymmetry(VMA), plus intermittent performances at inter cardinal locations The discrimination ability and speed of processing information vary as a function of eccentricity and isoeccentric locations across the visual fields. This implies that performance is not uniform at isoeccentric locations Performance Fields The performance fields are egocentric and allocentric, in egocentric the performance shifts with a head tilt, while in allocentric performance field, the performance shifts with distracters tilt. The performance fields are pervasive in vision, and they affect a wide range of detection, discrimination, and localization tasks, which are mediated by contrast sensitivity and spatial resolution. The performance fields exhibits a characteristic shape for each stimulus orientation, and luminous levels, with either monocular or binocular viewing conditionality’s. The ego centric and allocentric spatial reference frames, provides a subjective view that the brain builds a unitary spatial map of the world. The reference frame can further be subdivided into two categories such as: egocentric, which is observer centered coordinates, and allocentric, which is environment centered coordinates. Critical analysis of Research The critical analysis of the research comments upon the suitability of the research design, effectiveness of the process of data collection, validity of the sampling approach, and appropriateness of the chosen research methodology upon the subject being studied. Many professionals within the fields of education, psychology, management, and other social sciences perform research, and apply statistics to analyze their results, with many more reading the results of various researches, and applying the results to the real world. It is very necessary to critically analyze research reports so as to determine if the methodologies and results are valid, and apply to you as a professional. Considering a critical review of the research; Corbett JE, Carasco M (2011) Visual Performance Fields: Frames of Reference. Journal. Pone, and Van der Burg E, Cass J, Olivers CNL, Theeuwes J, Alais D (2010), Efficient Visual Search from Synchronized Auditory Signals Requires Transient Audiovisual Events. Both researches tend to test if there are locations in the human visual fields that perform better and visual search in both audio sine and square waves. In the visual performance fields, studied the perceptual consequences of spatial reference frame dissociations, in an experiment to show that better performance at isocentric locations along the horizontal than the vertical meridian of the visual field. It hypotheses that performance based on egocentric coordinates , such as tilting the observers head should result in a corresponding shift in the associated performance fields., against an allocentric frame of reference , such as tilting the stimuli should shift performance fields. In the methodology, the observers viewed briefly presented radial arrays of eight suprathreshhold Gabors, at four cardinal and four forty five degrees inter cardinal locations, equidistant from fixation, and determined the clock wise against counter clockwise tilt of a target Gabor. The results showed that the overall performance fields shifted with the position of the head. Therefore the results of the first experiment supported the proposal that performance fields shift, and are specific in terms of egocentric coordinates. The second experiment used four observers, who participated in a two, one hour sessions on fixation shifts. The result from experiment two showed that for every cardinal direction of fixation shifts (N, S, E, And W), as compared to the average performance of each of the four observers, at every corresponding eight target locations to their average performance. Therefore, the results support the fact that performance fields are retinotopic against head centric in nature. The implications of the study on visual displays are have varied influence of egocentric and allocentric manipulations on visual perception to underscore the significance in understanding how spatial reference frames mediate visual performance fields. The typical shape of visual performance fields are affected by the position of the head, the environment, and the retinal image which are dissociated will not encourage the understanding of the design and interpretation of a range of vision studies (Enroth-Cugell, &, Robson, 1984). Present Research The present research hopes to test if there are certain locations in the human visual field such as n, north, s, south, e, east, and w, west, that perform better in visual search with either an audio sine or square wave. This is related to the previous research, in that it also hoes to study the visual performance fields, which tested the perceptual consequences of spatial reference frame dissociations (Campbell, &, Robson, 1968; Zannoli, Cass, Mamassian, Alais, 2012). Hypothesis The present research hypothesizes that transient auditory information has the ability to efficiently drive the visual search in the inequality domain Method Participants: 23 participants (19 female) in return for course credit All reported right hand dominance Stimulus: A fixation point was presented in the middle of the screen. On each trial 19 luminance modulating disks would appear, located equidistantly from fixation on an imaginary circle with a radius of 15 degrees of visual angle. The diameter of each disk subtended a visual angle of 0.5 degrees The luminance of each disk varied in time from a minimum of 0.1 to a maximum of 165 cd/m2. The modulation of each disk was periodic, with each modulation cycle equaling 1 second. Two modulation cycles were presented on each trial. Although each disk modulated in luminance at the same rate (1 cycle/second = 1Hz), each disk modulated at a different phase (i.e. each disk reached maximum and minimum luminance at a slightly different time). The phase difference between temporally adjacent disks was equivalent to 50ms. On each trial, therefore, the maximum luminance of individual disks occurred at 0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850 & 900 ms into the trial. On each trial each temporal phase was allocated randomly to each of the 19 possible spatial locations. The temporal luminance modulation profile of all elements on a given trial was either sinusoidal or square-wave. This was determined randomly from trial-to-trial. On each trial a 500Hz tone was presented, the intensity of which matched the modulation rate of the visual elements. The phase of the tone was uniquely synchronized with a single visual element. The particular temporal phase of the synchronized audio-visual event varied randomly from trial-to-trial. The synchronized visual element was presented 20 times at each location under both square-wave and sinusoidal modulation conditions (a total of 760 trials per subject). Procedure: Subjects instructed to maintain their fixation on a centrally presented fixation point. At the conclusion of each trial subjects were asked to report which one of the nineteen disks’ luminance modulations was synchronized with the tone. This was achieved by typing the number corresponding to that particular disk into a dialogue box using a standard computer keyboard. Apparatus: Dark room Mitsubishi Diamond Pro computer monitor (1024 x 768 pixel resolution running at 100 Hz refresh rate) PC running E-Prime software Standard computer keyboard Tone presented through Sennheiser headphones. Subjects were seated 80 cm from the computer monitor. Results Results and discussion The after effects sizes varied with the density, both the readaptation and no-readaptation conditions produced varied results on separate repeated-measure ANOVAs. For example the log (ratio) after effects scores of each density. The log (ratio) scores was relatively stable with readaptation F (3, 7) =0.625, ns, without readaptation: F (3, 4) =0.452, ns. The repeated measure of the ANOVAs of five observers tested on both the conditions shows that the mean of the aftereffect score is reliably high in the adaptation condition M=log (1.66), than in the no-readapation condition, where m= log(1.42), F(1,5) = 16.3, p < 0.05. both the conditions had had marked bias especially towards seeing all the lower fileds as very dense. It is important to note that there awas no baseline data coledcted on the observers. However, four observers tested without the adaptation had revealed that there is no reliable bias. Their mean PSE log (ratio) scores of the log (0.98) Figure 1: mean aftereffect sizes in Experiment 1 for sessions with readaptation preceding each measurement trial and for sessions without readaptation (N=5). Interocular transfer of the short-term density aftereffects The total aftereffect measured in the subject’s readapted eye. The M=log (1.67), was very large than the other eye without the readaptation, M=log (1.42), F (1, 6) =8.87, p Read More