title: Investigation into factors affecting perceptual stability of the world during smooth pursuit eye movements

authors: Boer, Alexandra (Sasha)

subjects: perceptual stability

abstract: During pursuit eye movement, a stationary background projected on the retina shifts in the direction opposite to that of the eye movement. This complicates the perception of objects because during an eye movement the retinal and head-centric motions differ. Nevertheless, our visual system is somehow able to compensate for the added eye motion so that the world is perceived as stable. The eye movement compensation is traditionally assumed to consist of a combination of a retinal motion signal and an extra-retinal estimate of eye velocity (Von Holst & Mittelstaedt, 1950; Sperry, 1950).  This view has been expanded upon by a number of researchers in the last few decades with the introduction of vector addition-like models. However, it is not well known how closely the eye movement compensation mechanism follows the rules of vector algebra. Evidence for the presence of a signal coming from the moving eye has come from a variety of neurophysiological and perceptual research on the cortical Medial Superior Temporal (MST) area in primates. 

Previous studies have shown that the spatio-temporal structure of the background plays an important role in the perceptual accuracy of the velocity of a moving object in the visual field. Background characteristics have been shown to influence not only the retinal signal, but also the extra-retinal signal to some degree. The current thesis provides new information on factors that affect the degree of compensation for retinal motion during smooth pursuit eye movement. The findings are based on several experiments that were designed to use a range of pursuit target and stimulus dot velocities across different backgrounds and stimulus exposure times, in order to reveal details about how the retinal and extra-retinal signals are combined. Participants were asked to determine the direction of a moving stimulus by rotating an arrow on the screen. In a separate experiment, participants were also asked to assess the speed of a stimulus using a magnitude estimation task. A linear vector model was developed to separate the retinal and extra-retinal signal contribution to the overall compensation. This model was used to assess the degree of perceptual stability across different visual conditions. Generally, the data indicate that the perceived stimulus motion is well predicted by a vector subtraction mechanism postulated to be occurring in the human brain. However, in situations where there is weak visual stimulation, participants’ estimates of motion are less accurate and tend to follow the retinal image motion. In the current thesis I identify how the type of background, directions of eye movements, and stimulus velocities relative to the eye movements affected participants’ perceptual performance. Based on the data and the model fitting, it was concluded that the visual system appears to utilize the eye-movement related signal differentially depending on the retinal motion content.

text: Investigation into factors affecting perceptual stability of the world during smooth pursuit eye movements During pursuit eye movement, a stationary background projected on the retina shifts in the direction opposite to that of the eye movement. This complicates the perception of objects because during an eye movement the retinal and head-centric motions differ. Nevertheless, our visual system is somehow able to compensate for the added eye motion so that the world is perceived as stable. The eye movement compensation is traditionally assumed to consist of a combination of a retinal motion signal and an extra-retinal estimate of eye velocity (Von Holst & Mittelstaedt, 1950; Sperry, 1950).  This view has been expanded upon by a number of researchers in the last few decades with the introduction of vector addition-like models. However, it is not well known how closely the eye movement compensation mechanism follows the rules of vector algebra. Evidence for the presence of a signal coming from the moving eye has come from a variety of neurophysiological and perceptual research on the cortical Medial Superior Temporal (MST) area in primates. 

Previous studies have shown that the spatio-temporal structure of the background plays an important role in the perceptual accuracy of the velocity of a moving object in the visual field. Background characteristics have been shown to influence not only the retinal signal, but also the extra-retinal signal to some degree. The current thesis provides new information on factors that affect the degree of compensation for retinal motion during smooth pursuit eye movement. The findings are based on several experiments that were designed to use a range of pursuit target and stimulus dot velocities across different backgrounds and stimulus exposure times, in order to reveal details about how the retinal and extra-retinal signals are combined. Participants were asked to determine the direction of a moving stimulus by rotating an arrow on the screen. In a separate experiment, participants were also asked to assess the speed of a stimulus using a magnitude estimation task. A linear vector model was developed to separate the retinal and extra-retinal signal contribution to the overall compensation. This model was used to assess the degree of perceptual stability across different visual conditions. Generally, the data indicate that the perceived stimulus motion is well predicted by a vector subtraction mechanism postulated to be occurring in the human brain. However, in situations where there is weak visual stimulation, participants’ estimates of motion are less accurate and tend to follow the retinal image motion. In the current thesis I identify how the type of background, directions of eye movements, and stimulus velocities relative to the eye movements affected participants’ perceptual performance. Based on the data and the model fitting, it was concluded that the visual system appears to utilize the eye-movement related signal differentially depending on the retinal motion content.

year: 2011

title: Work-family responsibilities and support for women academics in Pakistan

authors: Imran, Romana

abstract: Globally women have a long history of negotiating between public and private life.  While each individual woman undertakes such negotiation, all women’s lives are already shaped by historical, political, religious and cultural forces.  This study focused on contemporary academic women in Pakistan and their experiences of negotiation between professional and family responsibilities – in an Islamic nation, shaped by an imperial history. In particular it investigated both the possibilities and limitations of family and institutional support as women worked to fulfil both work and family responsibilities.  
This qualitative study employed semi-structured interviews, with individuals from three groups:  women academics, husbands of women academics, and heads of department of two Pakistani universities. The data from these interviews were then read alongside selected theory, to produce accounts of the visible and invisible discourses shaping the positions available to women as they navigate family and career responsibilities.  The study’s findings show that patriarchal traditions that position men as breadwinners and women as homemakers are disturbed when women take up career opportunities in academia, at the same time as patriarchal gender practices rob women of opportunities they have earned, as in examples of a woman giving up a job offer in favour of her husband, or giving an academic husband financial support for publication. As a further example of contesting discourses, the study identifies that academic women are expected to be productive on the terms of  globalised neo-liberal education at the same time as a traditional school curriculum and teaching practices position educated women - parhi likihi- as responsible for the basics of their children’s learning within the home.  Academic women are caught in the tension between the expectations of globalised tertiary education and the reality of the limited material resources in universities in a developing country.  The analysis of women academics’ accounts of family support includes few but significant examples of disturbing and resisting patriarchal gender practices, in ways that the thesis argues contribute to a “democracy to come”.   However, for the most part, the narratives of support include women academics’ husbands’ limited contributions and stories of women academics’ struggles, compromises and sacrifices of their own career progression for their husbands’ careers.  The thesis argues that identifying the possibilities of questioning and undoing patriarchal gender practices and producing alternative discursive practices might open up possibilities for gender justice within family and academic institutions.

text: Work-family responsibilities and support for women academics in Pakistan Globally women have a long history of negotiating between public and private life.  While each individual woman undertakes such negotiation, all women’s lives are already shaped by historical, political, religious and cultural forces.  This study focused on contemporary academic women in Pakistan and their experiences of negotiation between professional and family responsibilities – in an Islamic nation, shaped by an imperial history. In particular it investigated both the possibilities and limitations of family and institutional support as women worked to fulfil both work and family responsibilities.  
This qualitative study employed semi-structured interviews, with individuals from three groups:  women academics, husbands of women academics, and heads of department of two Pakistani universities. The data from these interviews were then read alongside selected theory, to produce accounts of the visible and invisible discourses shaping the positions available to women as they navigate family and career responsibilities.  The study’s findings show that patriarchal traditions that position men as breadwinners and women as homemakers are disturbed when women take up career opportunities in academia, at the same time as patriarchal gender practices rob women of opportunities they have earned, as in examples of a woman giving up a job offer in favour of her husband, or giving an academic husband financial support for publication. As a further example of contesting discourses, the study identifies that academic women are expected to be productive on the terms of  globalised neo-liberal education at the same time as a traditional school curriculum and teaching practices position educated women - parhi likihi- as responsible for the basics of their children’s learning within the home.  Academic women are caught in the tension between the expectations of globalised tertiary education and the reality of the limited material resources in universities in a developing country.  The analysis of women academics’ accounts of family support includes few but significant examples of disturbing and resisting patriarchal gender practices, in ways that the thesis argues contribute to a “democracy to come”.   However, for the most part, the narratives of support include women academics’ husbands’ limited contributions and stories of women academics’ struggles, compromises and sacrifices of their own career progression for their husbands’ careers.  The thesis argues that identifying the possibilities of questioning and undoing patriarchal gender practices and producing alternative discursive practices might open up possibilities for gender justice within family and academic institutions.

year: 2023

title: Faith, politics and reconciliation: the Roman Catholic Church, New Zealand Maori and indigenous Australians

authors: O'Sullivan, Dominic

abstract: The Roman Catholic Church claims from Jesus Christ a mission to teach consistently religious ideals in accordance with its understanding of God’s constant truth. These ideals include the belief that human creation in the image and likeness of God establishes rights to dignity, to culture, to religious freedom, to self-determination and a share in the common good. These ideals form the basis of the unique contribution to human affairs which the Church claims it can make. Although these are religious goals for the Church, they require political realisation, which means that the Church cannot but be alert to the formation of alliances of common intellectual aspiration around concrete political issues so that secular expression and context can be given to the magisterium (the Church’s body of teaching). At the same time the Catholic hierarchy is conscious of a need for caution in how it responds to political events lest that religious mission be compromised by a perception of it as a partisan political lobby group, thus lessening its capacity to make its unique contribution to human affairs. 

The Second Vatican Council reaffirmed that the Church’s religious objectives do not exist in isolation from the political order because human law, which is developed through the secular political process, should conform to the religious natural law. Prior to the Council’s reaffirmation the Australian and New Zealand Churches generally, but not exclusively, understated or misunderstood this relationship and became impotent in challenging secular objectives inconsistent with religious aspiration. In contrast when the Church has accepted the relationship, as it has since the Second Vatican Council, it has positioned itself to identify opportunities to give secular context and expression to religious thought. Such opportunities increased from the 1960s onwards as political developments in both Australia and New Zealand saw a secular questioning of racism and a broadening of the parameters of secular political debate to the extent that established Catholic thought was shifted from the fringes to the widening mainstream of public opinion on indigenous policy. 

Although the Second Vatican Council required attention to the relationship between religious ends and political means, the changing secular environment was a significant factor in encouraging public advocacy in support of indigenous aspiration, which peaked in Australia in the 1990s with substantial Church interest in the native title debate and with the Church playing a leading role in the entrenchment of reconciliation - a religious concept - on the Australian political landscape. In New Zealand there has been an equal but less vocal interest in reconciliation because the political process itself established the Treaty of Waitangi as a political context for reconciliation and a context around which the Church has been able to focus its interest in the advancement of Maori aspiration. Yet, while the Treaty of Waitangi and the associated bicultural discourse have provided contexts for the expression of religious principle, they have also detracted from the Church’s use of its own magisterium as the moral authority for the articulation of its aspirations for Maori.

text: Faith, politics and reconciliation: the Roman Catholic Church, New Zealand Maori and indigenous Australians The Roman Catholic Church claims from Jesus Christ a mission to teach consistently religious ideals in accordance with its understanding of God’s constant truth. These ideals include the belief that human creation in the image and likeness of God establishes rights to dignity, to culture, to religious freedom, to self-determination and a share in the common good. These ideals form the basis of the unique contribution to human affairs which the Church claims it can make. Although these are religious goals for the Church, they require political realisation, which means that the Church cannot but be alert to the formation of alliances of common intellectual aspiration around concrete political issues so that secular expression and context can be given to the magisterium (the Church’s body of teaching). At the same time the Catholic hierarchy is conscious of a need for caution in how it responds to political events lest that religious mission be compromised by a perception of it as a partisan political lobby group, thus lessening its capacity to make its unique contribution to human affairs. 

The Second Vatican Council reaffirmed that the Church’s religious objectives do not exist in isolation from the political order because human law, which is developed through the secular political process, should conform to the religious natural law. Prior to the Council’s reaffirmation the Australian and New Zealand Churches generally, but not exclusively, understated or misunderstood this relationship and became impotent in challenging secular objectives inconsistent with religious aspiration. In contrast when the Church has accepted the relationship, as it has since the Second Vatican Council, it has positioned itself to identify opportunities to give secular context and expression to religious thought. Such opportunities increased from the 1960s onwards as political developments in both Australia and New Zealand saw a secular questioning of racism and a broadening of the parameters of secular political debate to the extent that established Catholic thought was shifted from the fringes to the widening mainstream of public opinion on indigenous policy. 

Although the Second Vatican Council required attention to the relationship between religious ends and political means, the changing secular environment was a significant factor in encouraging public advocacy in support of indigenous aspiration, which peaked in Australia in the 1990s with substantial Church interest in the native title debate and with the Church playing a leading role in the entrenchment of reconciliation - a religious concept - on the Australian political landscape. In New Zealand there has been an equal but less vocal interest in reconciliation because the political process itself established the Treaty of Waitangi as a political context for reconciliation and a context around which the Church has been able to focus its interest in the advancement of Maori aspiration. Yet, while the Treaty of Waitangi and the associated bicultural discourse have provided contexts for the expression of religious principle, they have also detracted from the Church’s use of its own magisterium as the moral authority for the articulation of its aspirations for Maori.

year: 2003