title: Ageing, Motion Perception and the Compensation for Eye Movements

authors: Rawley, Kirstyn Michelle

subjects: ageing

abstract: Smooth pursuit over a textured background introduces full-field motion to the retinal image in the direction opposing the eye movement. If this motion is not correctly attributed to the eye movement, it can be falsely perceived as motion in the world (Haarmeier, Thier, Repnow & Petersen, 1997). In order to correctly attribute retinal motion, the visual system must compensate for the effects of eye movements on the retinal image in motion perception. Visual motion perception is important for safely navigating the environment and has been linked to difficulties experienced by older adults while driving (Conlon & Herkes, 2008; Raghuram & Lakshminarayanan, 2006) and walking (Cavanaugh, 2002). The experiments reported in this thesis were devised in order to examine the effects of ageing on the perception of illusory motion during eye movements and therefore on the ability to compensate for eye movements in motion perception. The perception of motion during smooth pursuit eye movements was assessed in adults ranging in age from 17 to 79 years. The computer based task required participants to respond to the speed and direction of motion of a large-field random dot pattern while following a moving target dot with the eyes. For this task, a magnitude estimation tool was especially designed based on the direction response method of Bennett, Sekuler and Sekuler (2007). During the experimental session an eye tracker recorded the participant's eye movements. For the purposes of analysis, four groups were defined by age. It was found that the smooth pursuit of adults from ~40 years of age was slower than that of the younger age groups. With stationary eyes, the oldest age group ranging in age from 60 to 79 years tended to overestimate the speed of the dot pattern as compared to younger observers. This tendency decreased at higher background speeds. Eye movements appeared to affect the perception of the dot field's motion more in the group of participants ranging in age from 40 to 54 years than in the younger age groups. This also seemed to be the case for participants aged over 60 when viewing horizontal motion but not vertical motion. The results of this study suggest that older observers may be less able to compensate for the effects of eye movements on the retinal image. This could potentially affect their ability to safely and confidently navigate the environment.

text: Ageing, Motion Perception and the Compensation for Eye Movements Smooth pursuit over a textured background introduces full-field motion to the retinal image in the direction opposing the eye movement. If this motion is not correctly attributed to the eye movement, it can be falsely perceived as motion in the world (Haarmeier, Thier, Repnow & Petersen, 1997). In order to correctly attribute retinal motion, the visual system must compensate for the effects of eye movements on the retinal image in motion perception. Visual motion perception is important for safely navigating the environment and has been linked to difficulties experienced by older adults while driving (Conlon & Herkes, 2008; Raghuram & Lakshminarayanan, 2006) and walking (Cavanaugh, 2002). The experiments reported in this thesis were devised in order to examine the effects of ageing on the perception of illusory motion during eye movements and therefore on the ability to compensate for eye movements in motion perception. The perception of motion during smooth pursuit eye movements was assessed in adults ranging in age from 17 to 79 years. The computer based task required participants to respond to the speed and direction of motion of a large-field random dot pattern while following a moving target dot with the eyes. For this task, a magnitude estimation tool was especially designed based on the direction response method of Bennett, Sekuler and Sekuler (2007). During the experimental session an eye tracker recorded the participant's eye movements. For the purposes of analysis, four groups were defined by age. It was found that the smooth pursuit of adults from ~40 years of age was slower than that of the younger age groups. With stationary eyes, the oldest age group ranging in age from 60 to 79 years tended to overestimate the speed of the dot pattern as compared to younger observers. This tendency decreased at higher background speeds. Eye movements appeared to affect the perception of the dot field's motion more in the group of participants ranging in age from 40 to 54 years than in the younger age groups. This also seemed to be the case for participants aged over 60 when viewing horizontal motion but not vertical motion. The results of this study suggest that older observers may be less able to compensate for the effects of eye movements on the retinal image. This could potentially affect their ability to safely and confidently navigate the environment.

year: 2010

title: The effects of reinforcement context on the effectiveness of social consequences

authors: Osborne, Morton John

subjects: real-time video recording

abstract: The current study analyses the classroom social context; the rate of teacher task talk with respect to social consequences (praise and reprimand), in relation to the rate of on-task and unwanted behaviour of a target student in the classroom. Teacher behaviour talk (talk related to student conduct), social talk (social, non-academic talk) and proximity to the target student are also assayed.  Teacher verbal behaviour was recorded towards whom it was addressed: to the whole class, to a target student, to other students, and analysed severally and combined (summed) in relation to student on-task and unwanted behaviour.  Data were obtained by continuous recording of classroom behaviour and collated in to 60 second intervals.  All correlations were calculated on seconds of occurrence of that behaviour per minute.  This allowed for lagging the independent variable relative to dependent variables to better reflect the subsequent nature of the independent variable, such as praise and reprimand, rather than assaying contiguous relationships alone.  Results indicated that teacher verbal behaviour directed toward the target student did not relate significantly with student on-task behaviour or student unwanted behaviour.  The teacher verbal behaviour that related most significantly with both student on-task behaviour and student unwanted behaviour was teacher task talk to the whole class, followed by teacher task talk to the whole class, to the target student and to other students combined.  Teacher reprimand and behaviour talk directed toward the target student did not relate significantly with student on-task or unwanted behaviour.  Teacher reprimand and behaviour talk to the whole class, to the target student and to other students combined was significantly related to the decrease in student unwanted behaviour and increase in on-task behaviour given lag analysis for those teachers maintaining a high (greater than 50% of available time) rate of task talk. For teachers that did not do so, teacher verbal behaviour did not maintain significant relationships with student on-task or unwanted behaviour.  Results for this lower rate of teacher task talk were characterized by variability both in student behaviour and teacher verbal behaviour.  A case study was conducted increasing the general rate of teacher task talk which supported the above findings.  These results indicate that there is substantial commonality between student behaviour within the classroom and that teacher talk to the whole class and combined (i.e. the sum of addressing the whole class, the target student and other students) is significantly more predictive of individual student behaviour than is teacher talk directed to a target student alone. Teacher social talk was significantly related to teacher reprimand and behaviour talk.  Teacher proximity to the target student was not significantly related to student on-task or unwanted behaviour. The findings are discussed in relation to previous research findings and teaching practice.

text: The effects of reinforcement context on the effectiveness of social consequences The current study analyses the classroom social context; the rate of teacher task talk with respect to social consequences (praise and reprimand), in relation to the rate of on-task and unwanted behaviour of a target student in the classroom. Teacher behaviour talk (talk related to student conduct), social talk (social, non-academic talk) and proximity to the target student are also assayed.  Teacher verbal behaviour was recorded towards whom it was addressed: to the whole class, to a target student, to other students, and analysed severally and combined (summed) in relation to student on-task and unwanted behaviour.  Data were obtained by continuous recording of classroom behaviour and collated in to 60 second intervals.  All correlations were calculated on seconds of occurrence of that behaviour per minute.  This allowed for lagging the independent variable relative to dependent variables to better reflect the subsequent nature of the independent variable, such as praise and reprimand, rather than assaying contiguous relationships alone.  Results indicated that teacher verbal behaviour directed toward the target student did not relate significantly with student on-task behaviour or student unwanted behaviour.  The teacher verbal behaviour that related most significantly with both student on-task behaviour and student unwanted behaviour was teacher task talk to the whole class, followed by teacher task talk to the whole class, to the target student and to other students combined.  Teacher reprimand and behaviour talk directed toward the target student did not relate significantly with student on-task or unwanted behaviour.  Teacher reprimand and behaviour talk to the whole class, to the target student and to other students combined was significantly related to the decrease in student unwanted behaviour and increase in on-task behaviour given lag analysis for those teachers maintaining a high (greater than 50% of available time) rate of task talk. For teachers that did not do so, teacher verbal behaviour did not maintain significant relationships with student on-task or unwanted behaviour.  Results for this lower rate of teacher task talk were characterized by variability both in student behaviour and teacher verbal behaviour.  A case study was conducted increasing the general rate of teacher task talk which supported the above findings.  These results indicate that there is substantial commonality between student behaviour within the classroom and that teacher talk to the whole class and combined (i.e. the sum of addressing the whole class, the target student and other students) is significantly more predictive of individual student behaviour than is teacher talk directed to a target student alone. Teacher social talk was significantly related to teacher reprimand and behaviour talk.  Teacher proximity to the target student was not significantly related to student on-task or unwanted behaviour. The findings are discussed in relation to previous research findings and teaching practice.

year: 2019

title: Social deprivation in New Zealand

authors: Harcourt, Brian James

subjects: Deprivation

abstract: The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

text: Social deprivation in New Zealand The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

year: 2019