Beyond Left and Right Handedness: A Practice-based Approach to Assessing and Analysing Handedness Dimensions and Types

Foreword
Acknowledgment
Introduction
Why this Book?
Terminology Used in the Book
Overview of the Book
Contents
Part I: Understanding Handedness: Theory and Research
	1: The Emergence of Handedness
		1.1	 Introduction
		1.2	 The Evolution of Handedness
			1.2.1	 Handedness as an Inherited Evolutionary Trait
			1.2.2	 Language and Gestures as Drivers for Hemispheric Lateralisation
			1.2.3	 Task Demand, Complexity and Efficiency as Influencing Factors
			1.2.4	 The Emergence of Tool Use as a Driver for Handedness Ontogenesis
		1.3	 Development of Individual Handedness
			1.3.1	 Cascade Theory on Handedness Development
			1.3.2	 Developmental Phases of Handedness
			1.3.3	 Early Handedness Development and Related Processes
				Early Manual Asymmetry
				Early Neuromotor Development and Bimanual Coordination
			1.3.4	 Influencing Factors on Early Handedness Development
			1.3.5	 Handedness Groups in Infants
		1.4	 Describing Handedness
			1.4.1	 Definition of Handedness
			1.4.2	 Classification of Handedness
			1.4.3	 Distribution of Handedness
		1.5	 Concluding Remarks
		References
	2: Neural Asymmetries
		2.1	 Introduction
		2.2	 Structural Asymmetries
			2.2.1	 Primary Motor Cortex
			2.2.2	 Corpus Callosum
				Callosal Size and Handedness
				Function of Corpus Callosum
				Corpus Callosum and Bimanual Role Differentiation
			2.2.3	 Cerebellum
			2.2.4	 Corticospinal Tract
		2.3	 Functional Asymmetries
			2.3.1	 Footedness
			2.3.2	 Sensory Dominance
			2.3.3	 Language and Handedness
		2.4	 Manual Asymmetries
			2.4.1	 Crossing the Body Midline
			2.4.2	 Bimanual Cooperation and Coordination
				Development of Bimanual Coordination
				Mirror Movements
				Bimanual Coupling and Decoupling
				Bimanual Motor Learning
		2.5	 Concluding Remarks
		References
	3: Co-determinants of Handedness
		3.1	 Introduction
		3.2	 Inheritance of Handedness and Motor Abilities
			3.2.1	 Inheritance of Handedness
				Distributions of Left Handedness
				Twin Studies
				Familial Left Handedness
				Genetic Theories
				Molecular Genetics
				Polygenetic Predisposition
			3.2.2	 Inheritance of Motor Abilities
		3.3	 Development of Motor Abilities
			3.3.1	 Foundations for Motor Skills
			3.3.2	 Motor Planning
		3.4	 Environmental Influences
			3.4.1	 Pre-, Peri- and Postnatal Circumstances
				Environmental Influences Before Birth
				Environmental Influences at Birth
				Environmental Influences After Birth
			3.4.2	 Sociocultural and Physical Influences with a Rightward Bias
		3.5	 Pathological Handedness
		3.6	 Developmental Delay and Disorders
			3.6.1	 Motor-Based Developmental Disorders
			3.6.2	 Sensory-Motor Abilities and Handedness
			3.6.3	 Crossing the Body Midline Avoidance
		3.7	 The Essence of Research Perspectives
			3.7.1	 Summarising Influencing Factors on Handedness Formation
			3.7.2	 Distinguishing Between Developmental Delay and Pathological Handedness
		3.8	 Proposing a Model of Co-determinants of Handedness
		3.9	 Concluding Remarks
		References
	4: Left Handedness
		4.1	 Introduction
		4.2	 Familial Left Handedness
		4.3	 Typical Differences Between Left Handers and Right Handers
		4.4	 Pathological Left Handedness
			4.4.1	 Research on Pathological Left Handedness and Disorders
		4.5	 Converted Left Handers
			4.5.1	 Influencing Factors on Handedness Conversion
				Handwriting with the Non-dominant Hand as the Key Indicator
				Degrees of Handedness
			4.5.2	 Comparing Converted Left Handers to Non-converted Left Handers
			4.5.3	 Potential Switching Repercussions
				Types of Switching Repercussions
				Individual Case Studies on Switching Repercussions
				Summarising Switching Repercussions for a Practice-Based Approach
			4.5.4	 Comparing Converted Left Handers to Familial Left Handers and Right Handers
				Functional Magnetic Resonance Imaging (fMRI)
				Preference and Proficiency
			4.5.5	 Reverting Switched Left Handedness
				Individual Case Studies on Reverting Switched Left Handedness
				Understanding Brain Plasticity for Handedness Conversion and Reversion
				Research on Training with Non-dominant Hand for Writing
				Practical Implications
		4.6	 Identifying Subgroups of Left Handedness
		4.7	 Concluding Remarks
		References
	5: Mixed Handedness
		5.1	 Introduction
		5.2	 Contextualising Mixed Handedness
			5.2.1	 Defining Mixed Handedness and Related Terms
			5.2.2	 Reasons for Normal Handedness Variability
		5.3	 Ambidexterity
		5.4	 Analysing Research Methodology on Mixed-Handedness Studies
			5.4.1	 Criteria for Analysing Research Methodologies on Mixed Handedness
			5.4.2	 Results of Pilot Study Analysing Methodology of Studies on Mixed Handedness
		5.5	 Research Findings on Mixed Handedness
			5.5.1	 Mixed Handedness as an “Advantage”
			5.5.2	 Mixed Handedness as a “Disadvantage”
			5.5.3	 Dealing with Contradictory Results of Studies on Mixed Handedness
		5.6	 Proposing an Explanatory Model on Mixed Handedness (D-CC Hypothesis)
		5.7	 Compiling Criteria for Differentiating Mixed Handedness
		5.8	 Concluding Remarks
		References
Synopsis of Part I
Part II: Assessment and Analysis: Research and Practice
	6: Assessing Handedness
		6.1	 Introduction
		6.2	 Assessing Handedness: Preference and Proficiency
			6.2.1	 Assessing Hand Preference
				Self-Assessment Questionnaires
				Observation of Performing Hand Preference Tasks
				Using the Writing Hand as an Indicator of Handedness
				Crossing the Midline or Contralateral Reaching
				Third-Party Assessment
			6.2.2	 Assessing Hand Proficiency
		6.3	 Measuring Handedness
			6.3.1	 Measuring Handedness on a Continuum
			6.3.2	 Measuring Handedness According to Categories
		6.4	 Overview of Commonly Used Tests and Procedures
		6.5	 Factors Influencing Handedness Assessment
			6.5.1	 Motor Abilities Influencing Handedness and Its Assessment
			6.5.2	 Task Characteristics Influencing Handedness Assessments
			6.5.3	 Specific Factors Influencing Handedness Assessment Outcomes
		6.6	 A Multidimensional Approach to Assessing Handedness
			6.6.1	 Learning Lessons from the Literature
			6.6.2	 Summarising Recommendations from the Literature
			6.6.3	 Formulating Guidelines for a Practice-Based Handedness Assessment
		6.7	 Concluding Remarks
		References
	7: Constructing a Multidimensional Assessment: The Handedness Profile 2003
		7.1	 Introduction
		7.2	 Research Studies Developing a Multidimensional Assessment
			7.2.1	 Study I: Assessment of the Extent of Handedness in 5-Year-Old Preschool Children
				Background
				Test Material
				Method
				Results and Discussion
				Conclusion
			7.2.2	 Study II: Comparing Handedness Variability in Different Age Groups
				Background
				Test Development
				Method
				Results and Discussion
				Conclusion
			7.2.3	 Study III: Comparing Existing and Modified Tests for Typically Developed 6-Year-Olds
				Background
				Test Development
				Method
				Results and Discussion
				Conclusion
			7.2.4	 Study IV: Constructing a Normative Basis for the Handedness Profile
				Background
				Method
				Results and Discussion
				Conclusion
			7.2.5	 Study V: Assessing Children with Unestablished Handedness
				Background
				Method
				Results and Discussion
				Conclusion
		7.3	 Validating the Handedness Profile
			7.3.1	 Practicability Study (2010)
			7.3.2	 Reliability Study (2013)
			7.3.3	 Comparing Left- and Right-Handed 4- to 7-Year-Old Children During Simultaneous Bimanual Circle Drawing (2013)
			7.3.4	 Features of Laterality in Preschool Children (2015)
			7.3.5	 Digitising the Handedness Profile: dig-TEMA Project (2015)
			7.3.6	 Comparing Manual and Digital Scoring of the Handedness Profile (2015)
			7.3.7	 Laterality Features and Handedness in Adults (2019)
			7.3.8	 Follow-Up Digitisation Study: manDAAD Project (2019)
		7.4	 Concluding Remarks
		References
	8: Developing the Handedness Profile 2018
		8.1	 Introduction
		8.2	 Overview of the Handedness Profile 2018
		8.3	 Multivariate Information Relating to Co-determinants of Handedness (Qualitative Data)
			8.3.1	 Parent Questionnaire
			8.3.2	 Checklists on Quality of Motor Performance
			8.3.3	 General Observation Protocol
			8.3.4	 Laterality Profile
		8.4	 Multidimensional Subtests of the Handedness Profile (Quantitative Data)
			8.4.1	 Functional Hand Preference Test (FHPT)
			8.4.2	 Midline Crossing Test (MCT)
			8.4.3	 Trained Proficiency: Skill (Tracing and Dotting)
			8.4.4	 Untrained Proficiency: Ability (Hammering and Tapping)
			8.4.5	 Bimanual Proficiency: Bimanual Cooperation Test (BCT)
		8.5	 Tools for Analysis
			8.5.1	 Category Profile
			8.5.2	 Cluster Table with HP Stairs
		8.6	 Tools for Intervention
			8.6.1	 Differential Check
			8.6.2	 HP Axes
		8.7	 Scoring and Coding the Handedness Profile
			8.7.1	 Digitised Scoring Template
			8.7.2	 Handedness Code
		8.8	 Comparing the Handedness Profile to Other Handedness Assessments
		8.9	 Evaluation of the Handedness Profile by Trained Practitioners
			8.9.1	 Summary of Closed Questions
			8.9.2	 Perceived Benefits and Advantages of the Handedness Profile
			8.9.3	 Multidimensional Assessment, Comprehensiveness
			8.9.4	 Appropriateness for Children
			8.9.5	 Perceived Challenges and Recommendations Using the Handedness Profile
		8.10	 Concluding Remarks
		References
	9: Proposing an Architecture for a Handedness Typology
		9.1	 Introduction
		9.2	 Defining Six Dimensions of Handedness
		9.3	 Combining Multidimensional Handedness with Multivariate Co-Determinants
		9.4	 Identifying Distinct Handedness Groups from the Literature
		9.5	 Constructing Handedness Types and Variations Based on the Three Co-Determinants of Handedness
		9.6	 Specifying the Variations of the Handedness Types
		9.7	 Concluding Remarks
		Reference
	10: Interpreting Handedness Profiles Using the Handedness Typology
		10.1	 Introduction
		10.2	 Handedness Categories, Types and Variations
			10.2.1	 Interpreting Degree-Based Handedness Type (Inheritance) with D-Based Variations
				Description of D-Based Handedness Type
				The Relationship Between Degrees of Handedness and the D-Based Handedness Type
				The Relationship Between Motor Abilities and the D-Based Handedness Type
			10.2.2	 D-Based Variation Left Handedness (LH)
				Essentials from the Literature on Left Handedness (LH)
				Features of Left Handedness (LH)
				Prototypical Category Profile of Left Handedness (LH)
			10.2.3	 D-Based Variation Variable Left Handedness (VLH)
				Essentials from the Literature on Variable Left Handedness (VLH)
				Characteristics of Variable Left Handedness (VLH)
				Prototypical Category Profile of Variable Left Handedness (VLH)
			10.2.4	 D-Based Variation Right Handedness (RH)
				Essentials from the Literature on Right Handedness (RH)
				Characteristics of Explicit to Mild Right Handedness (RH)
				Prototypical Category Profile of Right Handedness (RH)
			10.2.5	 D-Based Variation Variable Right Handedness (VRH)
				Essentials from the Literature on Variable Right Handedness (VRH)
				Characteristics of Variable Right Handedness (VRH)
				Prototypical Category Profile of Variable Right Handedness (VRH)
			10.2.6	 D-Based Variation Ambidextrous Handedness (AH)
				Essentials from the Literature on Ambidexterity
				Characteristics of Ambidextrous Handedness
				Prototypical Profile of Ambidextrous Handedness
			10.2.7	 D-Based Variation Developmentally Delayed Handedness (DDH)
				Essentials from the Literature on Developmental Delay Affecting Handedness
				Characteristics of Developmentally Delayed Handedness (DDH)
				Prototypical Profile of Developmentally Delayed Handedness (DDH)
			10.2.8	 Interpreting Environment-Based Handedness Type with E-Based Variations
				Description of E-Based Handedness Type
				The Relationship Between Degrees of Handedness and the E-Based Handedness Type
				The Relationship Between Motor Abilities and the E-Based Handedness Type
			10.2.9	 E-Based Variation Converted Left Handedness (c-LH)
				Essentials from the Literature on Converted Left Handedness (c-LH)
				Characteristics of Converted Left Handedness (c-LH)
				Prototypical Category Profile of Converted Left Handedness (c-LH)
			10.2.10	 E-Based Variation Converted Right Handedness (c-RH)
				Essentials from the Literature on Converted Right Handedness (c-RH)
				Characteristics of Converted Right Handedness (c-RH)
				Prototypical Category Profile of Converted Right Handedness (c-RH)
			10.2.11	 Interpreting Motor-Based Handedness Type and Variations
				Description of the M-Based Handedness Type
				The Relationship Between Degrees of Handedness and the M-Based Handedness Type
				The Relationship Between Motor Abilities and the M-Based Handedness Type
			10.2.12	 M-Based Variation Pathological Left Handedness (p-LH)
				Essentials from the Literature on Pathological Left Handedness (p-LH)
				Characteristics of Pathological Left Handedness (p-LH)
				Prototypical Category Profile of Pathological Left Handedness (p-LH)
			10.2.13	 M-Based Variation Pathological Right Handedness (p-RH)
				Essentials from the Literature on Pathological Right Handedness (p-RH)
				Characteristics of Pathological Right Handedness (p-RH)
				Prototypical Profile of Pathological Right Handedness (p-RH)
		10.3	 Comparing Similar Prototypical Category Profiles Between the Handedness Variations
		10.4	 Concluding Remarks
		References
Synopsis of Part II
Part III: Intervention and Case Studies: Implications for Practice
	11: Intervention Strategies for Atypical Handedness and Related Problems
		11.1	 Introduction
		11.2	 Contextualising Guidelines for Intervention
			11.2.1	 Client-Centred Approach
			11.2.2	 Bottom-Up and Top-Down Approaches
			11.2.3	 Communication and Education
		11.3	 Left/Right Handedness with Motor Deficiencies (D-Based Variations)
		11.4	 Variable Left (or Right) Handedness (D-Based Variations) with Motor Deficiencies
		11.5	 Developmentally Delayed Handedness (D-Based Variation)
			11.5.1	 Bottom-Up Approach
			11.5.2	 Top-Down Approach
			11.5.3	 Leon-Leftie Weeks
			11.5.4	 The Stamina Test
		11.6	 Pathological Left or Right Handedness (M-Based Variation)
		11.7	 Reverting Converted Left Handedness (E-Based Variation)
			11.7.1	 Reverting to the Inherently Dominant Hand
			11.7.2	 Refraining from Reversion Training
		11.8	 Concluding Remarks
		References
	12: Case Studies Using the Handedness Profile
		12.1	 Introduction
		12.2	 Zelda: Variable Left Hander without Motor Deficiencies
			12.2.1	 Background Information
			12.2.2	 Results of Handedness Profile
				Functional Hand Preference Test (FHPT)
				Ability (Untrained Proficiency): Hammering and Tapping
				Skill (Trained Proficiency): Tracing and Dotting
				Crossing the Body Midline
				Bimanual Cooperation
				Category Profile
			12.2.3	 Interpretation and Summary
			12.2.4	 Recommendations
		12.3	 David: Pathological Right Hander
			12.3.1	 Background Information
			12.3.2	 Results of Handedness Profile
				Functional Hand Preference Test (FHPT)
				Ability (Untrained Proficiency): Hammering and Tapping
				Skill (Trained Proficiency): Tracing and Dotting
				Crossing the Body Midline
				Bimanual Circle Drawing
				Category Profile
			12.3.3	 Interpretation and Summary
			12.3.4	 Recommendations
				Follow-Up
		12.4	 Bernard: Converted Left Hander with Motor Deficiencies
			12.4.1	 Background Information
			12.4.2	 Results of Handedness Profile
				Functional Hand Preference Test (FHPT)
				Ability (Untrained Proficiency): Hammering and Tapping
				Skill (Trained Proficiency): Tracing and Dotting
				Crossing the Body Midline
				Bimanual Circles
				Category Profile
			12.4.3	 Summary and Interpretation
			12.4.4	 Recommendations
				Follow-Up
		12.5	 Hugo: Variable Left Hander with an Affected Left Side and Subsequent Handedness Reshaping
			12.5.1	 Background Information
			12.5.2	 Results of Handedness Profile
				Functional Hand Preference Test (FHPT)
				Ability (Untrained Proficiency: Hammering and Tapping)
				Skill (Trained Proficiency): Tracing and Dotting
				Crossing over the Body Midline
				Bimanual Cooperation
				Category Profile
			12.5.3	 Interpretation and Summary
			12.5.4	 Recommendations
				Follow-Up
		12.6	 Concluding Remarks
		References
Synopsis of Part III
Reflections: Implications for Practice, Theory and Research
References
Glossary
Index