Individual Differences and Developmental Psychology (Edexcel A-Level Psychology): Revision Notes
Individual Differences and Developmental Psychology
Introduction
Research on memory typically focuses on general theories that apply to most people. However, memory performance varies considerably between individuals due to differences in processing abilities, life experiences, age, and various developmental or neurological conditions. Understanding these individual differences provides a more complete picture of how memory functions across different populations.
While general memory theories help us understand common patterns, examining individual differences reveals that memory is not a uniform process. Factors such as cognitive speed, developmental stage, and neurological conditions all contribute to the unique way each person's memory operates.
Individual differences in memory
Processing speed and capacity
Individuals differ in their processing speed - the rate at which they can encode and handle new information. You may observe this in everyday situations, such as when some students take longer to copy notes from the board than others. These differences arise from variations in processing speed and short-term memory capacity.
Processing speed affects how quickly information can be transferred from sensory input into short-term storage. Individuals with faster processing speeds can encode more information in the same timeframe compared to those with slower processing speeds.
Developmental Changes in Memory Capacity
Memory capacity also changes with age. Younger children possess shorter digit spans than older children, indicating that memory capacity increases throughout development. This developmental pattern will be explored further in the study by Sebastián and Hernández-Gil (2012), discussed later in relation to developmental psychology.
Schemas and autobiographical memory
Bartlett's reconstructive memory theory proposes that individuals possess relatively similar schemas, but these schemas are heavily shaped by personal experience. This experiential influence affects how we perceive and encode information. For instance, a teacher might perceive a cylindrical drawing as a writing implement (pen), whereas a child might interpret it as an arrow or drumstick. These experience-based perceptions influence how objects and events are remembered. Similarly, the development of schemas affects information recall over time.
Autobiographical memory refers to memory for personal events, functioning like episodic memory but specifically relating to one's own life experiences. This form of memory is inherently individual, as it represents a collection of personalised events unique to each person.
Research Study: Palombo et al. (2012) - Survey of Autobiographical Memory
Palombo and colleagues (2012) conducted a large-scale investigation involving 598 volunteer participants to examine individual differences in autobiographical memory. They developed the Survey of Autobiographical Memory (SAM) to assess these differences.
Method: The survey subdivided autobiographical memory into four distinct domains:
- Episodic memory: memory for events
- Semantic memory: memory for facts
- Spatial memory: memory for locations and navigation
- Prospective memory: imagination and planning for future events
The questionnaire comprised 102 items which participants rated on a five-point Likert Scale, allowing for quantitative analysis of self-reported memory performance across these domains.
Key Findings from Palombo et al. (2012):
- Individuals who scored high or low on episodic memory tended to show corresponding high or low scores on semantic memory, suggesting these two memory systems are interconnected
- Males scored higher on spatial memory tasks compared to females, consistent with broader research on spatial abilities
- Participants with depression scored lower on both episodic and semantic memory measures, suggesting mood disorders may negatively affect these memory systems
This survey provides useful insight into self-reported patterns of naturalistic memory that laboratory conditions cannot easily capture. It offers valuable data on individual differences in autobiographical memory that might otherwise be difficult to observe.
Evaluation:
However, the study's reliance on self-report introduces potential limitations. Participants may have made inaccurate assessments or appraisals of their own memory performance, lacking the insight to judge their memory abilities accurately. This methodological concern should be considered when interpreting the findings.
Developmental psychology in memory
Developmental psychology is the branch of psychology investigating changes that occur throughout the lifespan. It examines both typical and atypical development, including how and when children acquire language and skills, but also when development deviates from expected patterns. In memory research, developmental psychologists have investigated conditions such as dyslexia and Alzheimer's disease in both younger and older populations.
Dyslexia
Dyslexia is a reading disorder characterised by difficulty recognising and decoding written text at an age-appropriate level. Children with dyslexia find reading fluently and accurately difficult, despite possessing normal comprehension abilities. The condition affects between 3% and 6% of children (some estimates suggest as high as 10%), with higher prevalence in boys than girls.
Key Characteristics of Dyslexia:
The disorder is characterised by particular difficulty with phonology - the speech sounds of language - which is essential for reading. The first indication of dyslexia typically appears as difficulty learning letter sounds and names, suggesting problems associating written symbols with their corresponding speech sounds. This phonological deficit leads to subsequent spelling and reading difficulties.
Evidence for memory deficits in dyslexia
Children with dyslexia demonstrate poor verbal short-term memory. This is evidenced through the phonological similarity effect (difficulty remembering similar-sounding words) and the word length effect (difficulty remembering sequences of long words compared to short words). These findings suggest children with dyslexia possess impaired short-term memory for processing speech sounds.
Research Study: McDougall et al. (1994)
McDougall et al. (1994) investigated the relationship between reading ability and memory by dividing 90 children into three reading ability groups: poor readers, moderate readers, and good readers. They measured memory spans for words and reading rates.
Findings: The results showed poor readers had lower memory spans and slower reading rates compared to the other groups.
Explanation: The explanation for this pattern centres on phonological processing speed. Good readers can articulate words quickly, leading to more words being represented phonologically in short-term memory. Poor readers articulate words more slowly, resulting in fewer words being held in short-term memory. This inefficiency in phonological processing and storage may underlie dyslexia.
Research Study: Alloway et al. (2009)
Alloway et al. (2009) provided further evidence by examining children with dyslexia and their working memory capacity. They investigated 46 children aged 6-11 years with reading disabilities.
Findings: The study discovered short-term working memory deficits that could explain their reading difficulties. The children could not hold speech sounds in working memory for long enough to bind them together to form complete words. They lacked the working memory capacity to store syllables long enough to assemble them into fluent words.
Research Study: Smith-Spark et al. (2010)
Smith-Spark et al. (2010) extended this research to adults with dyslexia. They compared adults with dyslexia to a control group of non-dyslexic participants.
Findings: Adults with dyslexia had unimpaired spatial working memory but impaired verbal working memory compared to the control group. Their results indicate a specific deficit in the phonological loop component of working memory in dyslexic individuals.
Research evidence strongly suggests that children and adults with dyslexia experience an underlying cognitive impairment that leads to difficulties processing and storing verbal information in short-term memory.
Comorbidity Issues:
However, establishing the exact role of verbal memory in causing dyslexia remains difficult. People with dyslexia present a range of sensory impairments affecting both auditory and visual systems. Additionally, dyslexia is often comorbid (occurring alongside other conditions) with learning difficulties, attention deficit hyperactivity disorder (ADHD), and other specific learning impairments. This interaction between dyslexia and related difficulties makes isolating phonological issues as the sole cause of reading impairment challenging.
Alzheimer's disease
Alzheimer's disease is a progressive, degenerative neurological disorder associated with ageing. It affects approximately one in twenty people (5% of the population), although the risk of development increases with age. Alzheimer's is the most common form of dementia and typically occurs after 65 years of age, but can develop as early as 40 years old. The disease is characterised by memory loss, concentration difficulties, confusion, and mood changes that progressively worsen over time.
Effects on memory systems
Normal ageing processes result in some loss of general cognitive functioning, but Alzheimer's disease selectively impairs certain cognitive systems rather than causing global deterioration.
Pattern of Memory Impairment in Alzheimer's:
Initially, Alzheimer's deteriorates the memory system for new events and information, whilst older information remains preserved. The disease also affects working memory, and central executive functioning becomes impaired, making complex tasks more difficult to coordinate. Visuospatial processing also becomes impaired in Alzheimer's disease.
A major characteristic of Alzheimer's is the inability to recall autobiographical information from episodic memory. This affects both short-term and long-term memory recall. The extent of memory loss correlates with the depletion of brain matter, particularly in the hippocampus and temporal cortex. The greater the brain damage, the more substantial the impairment. Typically, this damage and the associated impairment increases as the disease progresses.
Executive Functioning Impairments:
Loss of executive functioning results in a lack of general coordination and difficulty with attention. This reflects the breakdown of central executive functioning that coordinates multiple cognitive processes.
Research Study: Baddeley et al. (2001)
Baddeley et al. (2001) conducted a series of attentional tests on individuals with Alzheimer's disease and control participants to examine attentional deficits.
Method: One test involved searching for the letter 'Z' among easy and difficult distractor letters (letters that either looked similar to Z or not). They also employed a dual task procedure requiring participants to complete two attentional tasks simultaneously.
Findings: Patients with Alzheimer's performed worse on the difficult distractor task compared to control participants, and their performance was even more impaired on the dual task condition.
Conclusion: These results suggest dual attentional tasks are specifically impaired by Alzheimer's disease, reflecting the breakdown of central executive functioning that coordinates multiple cognitive processes.
Remember!
Key Points to Remember:
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Individual differences in memory arise from variations in processing speed, capacity, and personal experiences that shape our schemas
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Autobiographical memory can be divided into four domains: episodic, semantic, spatial, and prospective memory. Research shows these domains are interconnected, with episodic and semantic memory performance correlating
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Dyslexia is characterised by phonological processing difficulties that affect verbal short-term memory and working memory, particularly the phonological loop. Multiple studies demonstrate that individuals with dyslexia struggle to hold and manipulate speech sounds in working memory
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Alzheimer's disease selectively impairs memory systems, initially affecting memory for new events (episodic memory) whilst preserving older memories. The disease progressively damages the hippocampus and temporal cortex, with greater damage associated with more severe impairment
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Both dyslexia and Alzheimer's disease demonstrate how memory impairments can be specific to certain systems (verbal vs spatial, new vs old information) rather than affecting all aspects of memory equally