A cardinal role of selective visual attention is to serve our action by selecting all the relevant information. One task that has been applied extensively to explore attention is visual search for a target among distractors. Given the extensive practice of human observers with visual search, and its ecological relevance, one could expect a high level of efficiency when performing visual search tasks. Indeed, a prominent in the literature Ideal Observer model (Najemnik & Geisler, 2005, 2008) suggests, that human visual system is extremely efficient, in that every eye movement during visual search is executed to the locations that could be expected to yield maximum information; similarly to the Ideal Observer, humans require the minimum number of eye moments possible to find the target (Najemnik & Geisler, 2005, 2008). The present programme of research tests the prediction of the Ideal Observer model (Najemnik & Geisler, 2005, 2008) against a simpler, but similarly effective stochastic selection model (Clarke, Green, Chantler, & Hunt, 2016), by examining human visual search strategies under normal viewing conditions, and conditions that simulate visual field deficit. Across nine experiments, I observed strikingly inefficient search behaviour that speaks against the assumptions of the Ideal Observer model. Although on the surface these cumulative results appear to be in line with the random process of fixation selection (Clarke et al., 2016), such conclusion appears to be valid only for the observed group results. The individual observer's data that was carefully documented in each of the experiments did not allow such a conclusion. The individual observers' data showed full spectrum of search strategies, with some observers being extremely efficient, some being average searchers, and others applying a very inefficient strategy. The large individual differences between participants suggest that the fixation selection process is neither optimal nor random, but rather idiosyncratic.

Hindi and Urdu are two branches of the same language sometimes known as Hindustani. They are divided by orthography and geography but when spoken are sometimes indistinguishable. Both have contributed loanwords that have now been completely assimilated into the language. The question of how the eye behaves during Hindi reading when it encounters Urdu loanwords has not been focused on extensively in prior research. The main purpose of this thesis is to document the eye behavior during reading Sanskrit-based words and Urdu loanwords in Hindi. We place fifteen word pairs consisting of one target Hindi Sanskrit-based word and its Urdu loanword equivalent in different sentences. Native Hindi speakers participate to read Hindi sentences containing either Urdu loanwords or the Sanskrit root word in Hindi. To quantify the differences in reading Hindi and Urdu loanwords in Devanagari (Hindi script) sentences we use an eye tracking methodology, which is used to measure eye movements of a participant during reading. We discover very distinctive eye behavior during reading of Urdu loanwords in comparison to reading Hindi Sanskrit-based words. Analysis also shows an interaction in eye behavior due to language and frequency.

There is evidence to suggest that people from different cultures have different cognitive processing styles. For example, by measuring the eye movements of American and Chinese students when viewing pictures, Chua, Boland, and Nisbett (2005) found that American students fixated more on the focal object, whereas Chinese students fixated more on the background. In a subsequent object-recognition task, the Chinese students were less likely to correctly recognize old objects presented in new backgrounds than Americans did. This study used a similar scene-viewing task to investigate whether aging modulates these cultural differences in cognitive processing style. Like Chua et al., we found that young Chinese students spent longer fixating the background than did their Western counterparts. However, we failed to replicate the accompanying memory bias observed by Chua et al. Our strongest finding was that maintaining the original background facilitated memory for objects in young participants of both cultures but not for older participants. This result suggests that older adults had poorer memory for background details and/or had poorer integration of object and background.

Research applying eye-tracking to usability testing is increasing in popularity. A great deal of data can be obtained with eye-tracking, but there is little guidance as to how eye-movement data can be used in software usability testing. In the current study, users’ eye-movements were recorded while they completed a series of tasks on one of three e-commerce websites specializing in educational toys. Four main research questions were addressed in this study: (1) Are eye-tracking measures correlated with the more traditional measures of website usability (e.g., success, time on task, number of pages visited); (2) Are eye-tracking measures sensitive to differences in task difficulty; (3) Are eye-tracking measures sensitive to differences in site usability; and (4) How does the design of a website drive user eye-movements? Traditional usability performance measures consisted of time on task, number of pages visited, and perceived task difficulty. Eye-tracking measures included the number of fixations, total dwell time, and average fixation duration. In general, all these measures were found to be highly correlated with one another, with the exception of average fixation duration. The two groups of measures generally agreed on differences in task difficulty; tasks showing high scores on one variable (e.g., time on task) showed high results on other measures (e.g., number of fixations). Similar agreement among measures was observed in comparisons of the sites on each task. The unique contributions of eye-tracking to usability testing were best realized in qualitative examinations of eye-tracking data in relation to specific areas of interest (AOIs) on site pages, which demonstrated this to be a useful tool in understanding how aspects of design may drive users’ visual exploration of a web page. / Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Psychology. / "May 2005."

There is evidence to suggest that people from different cultures have different cognitive processing styles. For example, by measuring the eye movements of American and Chinese students when viewing pictures, Chua, Boland, and Nisbett (2005) found that American students fixated more on the focal object, whereas Chinese students fixated more on the background. In a subsequent object-recognition task, the Chinese students were less likely to correctly recognize old objects presented in new backgrounds than Americans did. This study used a similar scene-viewing task to investigate whether aging modulates these cultural differences in cognitive processing style. Like Chua et al., we found that young Chinese students spent longer fixating the background than did their Western counterparts. However, we failed to replicate the accompanying memory bias observed by Chua et al. Our strongest finding was that maintaining the original background facilitated memory for objects in young participants of both cultures but not for older participants. This result suggests that older adults had poorer memory for background details and/or had poorer integration of object and background.

The time-course of the attentional bias to threat in women and men was examined in order to clarify the validity of the "vigilant-avoidant hypothesis" and extend findings with spider pictures (Rinck and Becker, 2006) to other ecologically valid stimuli. Two hundred thirty-one (104 men, 127 women) participants pre-selected for high and low trait anxiety completed a battery of mood measures and viewed a series of slides with competing angry versus friendly faces. For a subset of these participants (54 men, 50 women), fixations and gaze durations were recorded via an eye tracker. All participants completed a face recognition task and provided copy and live measures of digit ratio (2D:4D), a putative marker of prenatal androgen exposure. Consistent with results from Rinck and Becker (2006), it was predicted that highly anxious individuals would show a vigilant-avoidant pattern toward angry faces while lesser anxious individuals would attend equally to angry and friendly faces over time. In addition, it was hypothesized that the vigilant-avoidant pattern would be stronger in highly anxious women. For secondary hypotheses, it was expected that digit ratio would correlate positively with trait anxiety and that attentional patterns for threat would differ between those with low and high digit ratio. Results did not support a heightened threat bias in high anxious versus low anxious individuals. Both groups showed an early bias for the angry female face during the first 1500 ms of presentation and a general avoidance for the angry male face over the course of 60 s. Although no association was found between trait anxiety and digit ratio, there was a negative correlation between reports of obsessive-compulsive symptoms and live left hand digit ratio in men. Moreover, early attentional patterns for angry faces appeared to differ between women with low and high digit ratio, suggesting that prenatal androgen action may lead to cognitive biases associated with the development and maintenance of anxiety.

The ability of the human eye to change its overall refractive power so that people can focus on objects both far and near is termed accommodation. Research into how the eye automatically changes its accommodation, demands an instrument capable of tracking the accommodation with fine resolution and adequate corner frequency. An instrument capable of tracking the ocular accommodation is called an optometer. Reports of earlier optometers show that optometers using the older Scheiner principlecan have the required precision and dynamics required to track the micro fluctuations accommodation. However optometers using the Scheiner principle require precise alignment to the patient’s pupil to be maintained throughout the measurement time. Previous optometers have used the radiation reflected from the patient’s cornea (calledthe corneal reflection) to initially align the optical axis of the optometer to the centre of the patient’s pupil. Since the Scheiner principle optometer uses radiant energy reflected from the patient’s retina to make a refractive measurement, the idea of using this same radiant energy for patient alignment is investigated. Earlier optometers have blocked the corneal reflection from reaching the photodetectors for the retinal reflection using a small fixed light stop. Since it is not possible to use a fixed light stop if the retinal reflection is used for alignment, the feasibility of using crossed linear polarizers is experimentally evaluated. The results showed that about78% of the radiant energy reflected from the front lens of an artificial eye could be eliminated using crossed linear polarizers. Whether the Scheiner principle measurement of refraction of an artificial eye could be done with 78% of the front lens (corneal) reflection removed was investigated. The results were not conclusive. There was not a measureable indication of when the refraction of the experimental optometer matched that of the artificial eye. The experimental optometer system attempts to use a servo controlled mirror system to move the optical axis of the optometer so that it coincides with the optical axis of an artificial eye. The design, development and testing of the mirror system is described. The mirror system enables the optometer to perform a two dimensional scan over the pupil plane of the patient’s eye or an artificial eye. During the scanning, the total radiant power reflected can be measured. For the optometer to be aligned using radiation reflected from the retina, a scan of the pupil plane of should reveal the pupil boundaries. This was experimentally demonstrated to work. Unfortunately time limitations did not permit further development of an automatic eye alignment and tracking system.

The ability of the human eye to change its overall refractive power so that people can focus on objects both far and near is termed accommodation. Research into how the eye automatically changes its accommodation, demands an instrument capable of tracking the accommodation with fine resolution and adequate corner frequency. An instrument capable of tracking the ocular accommodation is called an optometer. Reports of earlier optometers show that optometers using the older Scheiner principlecan have the required precision and dynamics required to track the micro fluctuations accommodation. However optometers using the Scheiner principle require precise alignment to the patient’s pupil to be maintained throughout the measurement time. Previous optometers have used the radiation reflected from the patient’s cornea (calledthe corneal reflection) to initially align the optical axis of the optometer to the centre of the patient’s pupil. Since the Scheiner principle optometer uses radiant energy reflected from the patient’s retina to make a refractive measurement, the idea of using this same radiant energy for patient alignment is investigated. Earlier optometers have blocked the corneal reflection from reaching the photodetectors for the retinal reflection using a small fixed light stop. Since it is not possible to use a fixed light stop if the retinal reflection is used for alignment, the feasibility of using crossed linear polarizers is experimentally evaluated. The results showed that about78% of the radiant energy reflected from the front lens of an artificial eye could be eliminated using crossed linear polarizers. Whether the Scheiner principle measurement of refraction of an artificial eye could be done with 78% of the front lens (corneal) reflection removed was investigated. The results were not conclusive. There was not a measureable indication of when the refraction of the experimental optometer matched that of the artificial eye. The experimental optometer system attempts to use a servo controlled mirror system to move the optical axis of the optometer so that it coincides with the optical axis of an artificial eye. The design, development and testing of the mirror system is described. The mirror system enables the optometer to perform a two dimensional scan over the pupil plane of the patient’s eye or an artificial eye. During the scanning, the total radiant power reflected can be measured. For the optometer to be aligned using radiation reflected from the retina, a scan of the pupil plane of should reveal the pupil boundaries. This was experimentally demonstrated to work. Unfortunately time limitations did not permit further development of an automatic eye alignment and tracking system.

Robotics have advanced to include highly anthropomorphic (human-like) entities. A novel eye-tracking paradigm was developed to assess infants’ sensitivity to communicative gestures by human and robotic informants. Infants from two age groups (5-9 months, n = 25; 10-15 months, n = 9) viewed a robotic or human informant pointing to locations where events would occur during experimental trials. Trials consisted of three phases: gesture, prediction, and event. Duration of looking (ms) to two areas of interest, target location and non-target location, was extracted. A series of paired t-tests revealed that only older infants in the human condition looked significantly longer to the target location during the prediction phase (p = .036). Future research is needed to tease apart what components of the robotic hand infants respond to differentially, and whether a robotic hand can be manipulated to increase infants’ sensitivity to social communication gestures executed by said robotic hand. / Includes bibliography. / Thesis (MA)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

archives@tulane.edu / Making eye contact is one of the earliest, most important forms of communication. Newborns are sensitive to adults’ gaze direction (Farroni, Massaccesi, Pividori, & Johnson, 2004), and by 4 months infants learn more about an object that an adult has looked at (Reid & Striano, 2005). Emotional facial expressions influence infants’ scanning of adults’ eyes (Shepard & Spence, 2012), which may affect their sensitivity to eye gaze cues. In two experiments, we examined the effects of silent dynamic emotional messages on 6-month-old infants’ scanning of face features, as well as their sensitivity to and learning from eye gaze cues. In Experiment 1, infants completed a gaze cueing task in which speakers delivered silent approving, comforting, prohibition, and neutral messages and then shifted their eye gaze to a peripheral target. Although infants showed increased attention to the eyes during prohibition and comforting messages, all infants showed enhanced gaze cueing in the context of approving messages. Moreover, female infants showed trend-level gaze cueing following approving messages, whereas male infants showed trend-level gaze cueing following neutral messages. In Experiment 2, a separate group of infants completed a similar gaze cueing task that included a visual paired comparison test phase to examine learning of the gaze-cued and non-cued targets, based on the hypothesis that increased sensitivity to gaze cues would enhance learning of the cued targets. As in Experiment 1, infants showed increased attention to the eyes during comforting messages. However, we did not find any reliable gaze cueing effects. Infants spent more time looking at test targets following approving messages but did not show evidence of enhanced learning of cued targets. Overall, findings from both experiments suggest that 6-month-olds are more responsive to gaze cues in the context of approving messages, underscoring the significance of positive infant-directed interactions to the development of early joint attention. We conclude by discussing clinical implications, limitations (including a relevant error in Experiment 2), and future directions. / 1 / Claire Frances Noonan