title: Disrupting working memory to reduce verbal-analytical engagement in motor performance: Squeezing in a tiresome new approach to implicit motor learning!

authors: Hoskens, Merel Cornelie Janna

subjects: Implicit motor learning

abstract: Implicit motor learning paradigms aim to minimise verbal-analytical engagement during motor performance. Some do this by suppressing working memory activity during practice. This reduces the ability of the learner to use, manipulate and store task-related information via mental processes, such as hypothesis testing. Implicit motor learning paradigms that suppress working memory indirectly are not always effective, because individual differences, such as motivation, can override their efficiency. The aim of this thesis was to investigate whether two more direct methods, cognitive fatigue and hand contractions, are viable tools with which to suppress working memory activity during motor practice, and whether they cause reduced verbal-analytical engagement in motor performance.
Chapter 2 investigated whether a computer-based cognitive fatigue task suppressed working memory activity during a golf putting task. Behavioural measures of verbal-analytical engagement were employed to test whether the cognitive fatigue task reduced hypothesis testing during the subsequent golf putting task. Results revealed that the computer-based cognitive fatigue task promoted cognitive fatigue, but was not sufficient to cause reduced hypothesis testing compared to a non-fatigue group.
In Chapter 3, a cognitive fatigue task with greater emphasis on motor control was therefore designed. It was first established whether the task caused cognitive fatigue and if working memory functions were disrupted. Subsequently, it was established whether the cognitive fatigue task reduced hypothesis testing during performance of a novel shuffleboard task, using behavioural measures, including self-report and assessment of technique changes. Additionally, verbal-analytical engagement in motor planning was gauged, using electroencephalography (EEG) to assess alpha power over the left temporal verbal-analytical (T7) site plus connectivity between the T7 and Fz (motor planning mid-frontal) sites. The results revealed that the motor-specific cognitive fatigue manipulation caused increased, rather than decreased, verbal-analytical engagement in motor performance, compared to a no fatigue control condition.
Chapter 4 examined whether hand contraction protocols influenced cognitive processes during motor performance, by using EEG to gauge verbal-analytical engagement during motor planning (i.e., T7-Fz connectivity) following a left-hand, right-hand or no hand-contraction protocol. The findings revealed that left-hand contractions, which are thought to activate the less verbal right hemisphere and deactivate the more verbal left hemisphere, caused reduced verbal-analytical engagement in motor planning, compared to the other protocols. Furthermore, right-hand contractions caused higher levels of verbal-analytical engagement in motor planning. Consequently, Chapter 5 investigated whether left-hand contractions promoted implicit motor learning. Participants practiced a motor task following regular bouts of left-hand contractions, right-hand contractions or no hand-contractions. Behavioral measures were used to gauge the extent to which verbal-analytical engagement was curtailed or encouraged. The results revealed no evidence that left-hand contractions promoted implicit motor learning, and both left-hand and right-hand contractions caused worse performance than no hand-contractions during a post-practice test phase.
Working memory performance was disrupted by both the cognitive fatigue and hand contraction protocols; however, predicted decrements in verbal-analytical engagement did not occur, and implicit motor learning was not promoted. The findings of this thesis reveal the complexity of the interrelationships between working memory, verbal-analytical processes and brain activity during motor learning. Future directions for research are considered.

text: Disrupting working memory to reduce verbal-analytical engagement in motor performance: Squeezing in a tiresome new approach to implicit motor learning! Implicit motor learning paradigms aim to minimise verbal-analytical engagement during motor performance. Some do this by suppressing working memory activity during practice. This reduces the ability of the learner to use, manipulate and store task-related information via mental processes, such as hypothesis testing. Implicit motor learning paradigms that suppress working memory indirectly are not always effective, because individual differences, such as motivation, can override their efficiency. The aim of this thesis was to investigate whether two more direct methods, cognitive fatigue and hand contractions, are viable tools with which to suppress working memory activity during motor practice, and whether they cause reduced verbal-analytical engagement in motor performance.
Chapter 2 investigated whether a computer-based cognitive fatigue task suppressed working memory activity during a golf putting task. Behavioural measures of verbal-analytical engagement were employed to test whether the cognitive fatigue task reduced hypothesis testing during the subsequent golf putting task. Results revealed that the computer-based cognitive fatigue task promoted cognitive fatigue, but was not sufficient to cause reduced hypothesis testing compared to a non-fatigue group.
In Chapter 3, a cognitive fatigue task with greater emphasis on motor control was therefore designed. It was first established whether the task caused cognitive fatigue and if working memory functions were disrupted. Subsequently, it was established whether the cognitive fatigue task reduced hypothesis testing during performance of a novel shuffleboard task, using behavioural measures, including self-report and assessment of technique changes. Additionally, verbal-analytical engagement in motor planning was gauged, using electroencephalography (EEG) to assess alpha power over the left temporal verbal-analytical (T7) site plus connectivity between the T7 and Fz (motor planning mid-frontal) sites. The results revealed that the motor-specific cognitive fatigue manipulation caused increased, rather than decreased, verbal-analytical engagement in motor performance, compared to a no fatigue control condition.
Chapter 4 examined whether hand contraction protocols influenced cognitive processes during motor performance, by using EEG to gauge verbal-analytical engagement during motor planning (i.e., T7-Fz connectivity) following a left-hand, right-hand or no hand-contraction protocol. The findings revealed that left-hand contractions, which are thought to activate the less verbal right hemisphere and deactivate the more verbal left hemisphere, caused reduced verbal-analytical engagement in motor planning, compared to the other protocols. Furthermore, right-hand contractions caused higher levels of verbal-analytical engagement in motor planning. Consequently, Chapter 5 investigated whether left-hand contractions promoted implicit motor learning. Participants practiced a motor task following regular bouts of left-hand contractions, right-hand contractions or no hand-contractions. Behavioral measures were used to gauge the extent to which verbal-analytical engagement was curtailed or encouraged. The results revealed no evidence that left-hand contractions promoted implicit motor learning, and both left-hand and right-hand contractions caused worse performance than no hand-contractions during a post-practice test phase.
Working memory performance was disrupted by both the cognitive fatigue and hand contraction protocols; however, predicted decrements in verbal-analytical engagement did not occur, and implicit motor learning was not promoted. The findings of this thesis reveal the complexity of the interrelationships between working memory, verbal-analytical processes and brain activity during motor learning. Future directions for research are considered.

year: 2020

title: Clay minerals in South Australian Holocene basaltic volcanogenic soils and implications for halloysite genesis and structure

authors: Churchman, G. Jock

abstract: The clay mineralogical composition was determined of 8 soils formed from pyroclastic ejecta (tephra) from adjacent 5000-year old basaltic volcanoes at Mounts Gambier and Schank in South Australia. Both nanocrystalline (short-range order) and crystalline aluminosilicates and also Fe oxides and hydroxides were identified in the soils. Allophane generally occurred to a greater extent in the 4 soils derived from glass-rich Mt Schank tephra than in most of those from glass-poor Mt Gambier tephra. Ferrihydrite occurred along with allophane. Smectite, kaolinite, illite, and an interstratified kaolinite-smectite comprised the crystalline minerals in these soils. There was no evidence for halloysite. Unlike in New Zealand, decreased leaching resulted in Si-rich allophane, rather than halloysite, forming in place of the Al-rich form of the same mineral. This result may indicate that ferrous iron is an essential impurity in halloysite. It was likely absent from these soils because their high pH due to underlying calcareous rocks precludes its occurrence. The probable requirement of Fe(II) as an essential component of halloysites may have been overlooked because of oxidation consequent upon the inevitable drying of samples prior to analyses.

text: Clay minerals in South Australian Holocene basaltic volcanogenic soils and implications for halloysite genesis and structure The clay mineralogical composition was determined of 8 soils formed from pyroclastic ejecta (tephra) from adjacent 5000-year old basaltic volcanoes at Mounts Gambier and Schank in South Australia. Both nanocrystalline (short-range order) and crystalline aluminosilicates and also Fe oxides and hydroxides were identified in the soils. Allophane generally occurred to a greater extent in the 4 soils derived from glass-rich Mt Schank tephra than in most of those from glass-poor Mt Gambier tephra. Ferrihydrite occurred along with allophane. Smectite, kaolinite, illite, and an interstratified kaolinite-smectite comprised the crystalline minerals in these soils. There was no evidence for halloysite. Unlike in New Zealand, decreased leaching resulted in Si-rich allophane, rather than halloysite, forming in place of the Al-rich form of the same mineral. This result may indicate that ferrous iron is an essential impurity in halloysite. It was likely absent from these soils because their high pH due to underlying calcareous rocks precludes its occurrence. The probable requirement of Fe(II) as an essential component of halloysites may have been overlooked because of oxidation consequent upon the inevitable drying of samples prior to analyses.

year: 2014

title: Breaking the consensus: The politicisation of Maori affairs

authors: Barber, Keith

subjects: Tremewan

abstract: This article takes issue with the claim made by Tremewan (2005a) that the
New Zealand social sciences have been uncritical of neotraditionalist and
culturalist trends in social policy. It points out that at least since the 1980s
there has existed a significant body of social science literature critical of these trends. The article also takes issue with Tremewan’s attribution of increased political dissent in the area of Maori affairs to the culturalist ideological currents dominating social policy. The article provides an alternative explanation for this increase in political dissent by focusing upon the material conditions of existence and the opportunism of power-seeking politicians.

text: Breaking the consensus: The politicisation of Maori affairs This article takes issue with the claim made by Tremewan (2005a) that the
New Zealand social sciences have been uncritical of neotraditionalist and
culturalist trends in social policy. It points out that at least since the 1980s
there has existed a significant body of social science literature critical of these trends. The article also takes issue with Tremewan’s attribution of increased political dissent in the area of Maori affairs to the culturalist ideological currents dominating social policy. The article provides an alternative explanation for this increase in political dissent by focusing upon the material conditions of existence and the opportunism of power-seeking politicians.

year: 2006