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Studying Cognition
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Studying Cognition

What is Cognitive Psychology?

Overview of Cognitive Psychology

  • The lecture continues from the previous class, focusing on cognitive psychology's subject matter and its various inputs from different psychological schools.
  • Discussion centers on understanding mental events and processing, emphasizing the role of cognition in studying how the mind operates.

Methods of Studying Cognition

  • Early cognitive psychology relied heavily on information processing theory, which focused on mental mechanisms without considering brain involvement.
  • Information processing theory examines how mental activities are generated through specific processes and structures.

The Role of the Brain in Cognitive Psychology

Importance of Brain Study

  • Emphasizes that understanding dissociations and associations in cognitive processes requires including brain studies to identify active areas during cognitive tasks.
  • New approaches in cognitive psychology integrate brain area studies with traditional methods like information processing and artificial intelligence.

Multiple Methods for Comprehensive Understanding

  • Acknowledges that each method for studying cognition has limitations; combining them can provide a more complete picture.
  • Using multiple methods allows researchers to leverage strengths from one approach to compensate for weaknesses in another, enhancing overall understanding.

Dissociation and Association in Cognitive Processes

Defining Key Concepts

  • Dissociation refers to situations where activation occurs in one brain area for a task but not another, helping identify which tasks require specific mental processes.

Example: Working Memory Model

  • Introduces Allen Bradley's concept of working memory, highlighting the central executive's role in managing auditory and visual inputs separately.
  • Discusses experiments designed to determine if different types of input (auditory vs. visual) activate distinct brain areas or share common processes.

Understanding Cognitive Processes through Dissociation and Association

The Role of Allen Bradley's Research

  • Allen Bradley conducted studies to explore brain functions by isolating visual input, revealing that auditory processing remained intact despite visual task overload.
  • His experiments aimed to determine if visual input overload affects auditory processing, suggesting dissociative processes in working memory for different sensory inputs.
  • Subjects struggled with visual tasks under heavy cognitive load but could still retrieve auditory information effectively, indicating distinct processing pathways for vision and hearing.

Importance of Dissociation in Cognition

  • The concept of dissociation is crucial in cognitive studies as it helps identify which brain processes are similar yet operate via different mechanisms.
  • Research on spatial representations showed that different brain regions can encode similar spatial information, highlighting the complexity of cognitive functions.
  • Understanding how various processes converge or diverge from specific tasks aids in pinpointing the specificity of cognitive operations.

Methods for Studying Cognition

Behavioral Methods

  • Four primary methods exist for studying cognition: behavioral methods, correlation neural methods, causal methods, and modeling approaches (including box models and neural networks).

Observational Insights

  • Behavioral methods focus on observable behaviors like reaction times and accuracy during mental events to infer underlying cognitive processes.

Accuracy Method

  • The accuracy method assesses retrieval effectiveness through tasks like item recall; it provides objective insights into mental processing efficiency.
  • Limitations include ceiling effects (tasks too easy leading to high scores with little insight into processing mechanisms) and floor effects (tasks too difficult resulting in no correct responses).

Response Time Method

  • This method measures the time taken for responses; it's objective and useful for understanding both conscious and unconscious processing mechanisms.
  • However, it faces challenges such as experimental expectancy effects where researchers' biases may influence subject behavior during experiments.

Cognitive Processing Methods

Behavioral Methods in Cognitive Research

  • The third method discussed is the judgment method, where participants use a scale (7, 8, or 9 points) to rate their cognitive processing of items. This method is cost-effective and captures subjects' reactions.
  • Participants can express their feelings on a judgment scale, but there are challenges as they may not understand how to use the scale effectively.
  • Another behavioral method is protocol collection, which requires subjects to verbalize their thought processes during tasks, such as counting. This provides insight into mental steps involved in cognitive tasks.
  • The protocol method reveals basic steps in mental processing but struggles with complex tasks where individuals may lack awareness of their cognitive processes.

Correlation and Neural Methods

  • The next approach involves correlation or neural methods, focusing on brain localization to explain cognitive processes. It examines how mental events are processed within the brain.
  • This method aims to correlate specific brain activity with mental events, allowing researchers to identify which areas of the brain are responsible for various cognitive functions.
  • A challenge arises when multiple brain areas activate simultaneously, complicating efforts to pinpoint specific regions linked to particular mental processes.
  • Correlation does not imply causation; just because two events occur together does not mean one causes the other. This limitation makes it difficult to establish direct relationships between brain activity and cognitive events.

Techniques for Studying Brain Activity

  • There are three primary techniques used within correlation neural methods: neurophysiological studies, transcranial magnetic stimulation, and drug studies that explore brain function related to cognition.
  • One significant issue with correlation methods is that while certain areas show synchronized activity, it doesn't confirm that one area influences another directly—making causal interpretations challenging.
  • The first technique mentioned is EEG (electroencephalography), which records electrical potentials from the scalp during mental activities, providing insights into real-time brain function associated with cognition.

Understanding EEG and Brain Activity

Changes in Neuronal Polarity

  • When mental activity occurs, changes in neuronal polarity lead to weak electrical currents that can be detected on the scalp surface by EEG sensors.
  • The baseline activity represents a state of no mental processing; deviations from this baseline indicate active mental processes.

Event-Related Potentials (ERPs)

  • ERPs are recorded following specific stimuli, capturing brain responses over time to understand cognitive processes.
  • The EEG captures patterns of brain activity from stimulus onset to response, revealing which areas are engaged during different tasks.

Brain Wave Patterns

  • Alpha activity (8-13 Hz) is common during relaxed states; as relaxation increases, amplitude rises while frequency decreases towards delta waves.
  • The P300 component appears 300 milliseconds after a novel stimulus, indicating the brain's response to new information.

Limitations and Advantages of EEG

  • While EEG has poor spatial resolution due to the conical structure of current flow in the brain, it excels in temporal resolution, detecting events within milliseconds.
  • The non-invasive nature and low cost of EEG make it accessible for various applications in cognitive psychology.

Comparing EEG with MEG and PET

Magnetoencephalography (MEG)

  • MEG captures magnetic rather than electrical activity from neurons, providing insights into auditory cortex functions with high spatial resolution under one centimeter.
  • Despite its advantages in spatial and temporal resolution, MEG systems are expensive and require sophisticated technology for operation.

Positron Emission Tomography (PET)

  • PET uses radioactive isotopes like oxygen-15 injected into the body to track blood flow changes associated with neural activity during cognitive tasks.

Understanding Brain Imaging Techniques

Overview of PET Scans

  • The use of the oxygen-15 isotope in Positron Emission Tomography (PET) is primarily for studying language processing areas in the brain.
  • PET scans have high spatial resolution (up to 1 cm) but poor temporal resolution, taking about 40 seconds to generate an image.
  • Although the radioactivity from oxygen-15 is low (comparable to what an airline pilot experiences in six months), it still poses some health risks.

MRI and fMRI Advancements

  • Magnetic Resonance Imaging (MRI) assesses structural integrity, while functional MRI (fMRI) measures blood oxygen levels during brain activity.
  • MRI operates on body magnets aligning with an external magnetic field, generating images based on how quickly atoms return to alignment after being disturbed by radio pulses.
  • fMRI compares oxygenated and deoxygenated blood flow in active brain regions, providing insights into which areas are engaged during specific tasks.

Resolution and Invasiveness Comparisons

  • Both MRI and fMRI offer excellent spatial resolution but have limited temporal resolution compared to EEG, which provides millisecond-level data.
  • While MRI techniques are less invasive since they do not require injections, their high purchase costs stem from the expensive electromagnets used.

Optical Imaging Method

  • A newer technique involves using lasers that penetrate the brain; analyzing returning light can indicate blood flow in specific areas.
  • This method currently has poor spatial resolution and takes several minutes for image formation; its invasiveness is medium due to laser application.

Causal Neural Methods in Cognition Studies

  • Causal neural methods explore cognitive functions by examining patients with localized brain damage, such as those affecting Broca's area responsible for speech.
  • By comparing speech-related tasks between affected individuals and healthy controls, researchers can infer the roles of specific brain regions.

Understanding Cognitive Processes through Brain Damage and Stimulation

The Role of Brain Damage in Cognitive Studies

  • Research on brain damage involves comparing cognitive processes between individuals with specific brain injuries and those without. This helps to understand how different mental activities are processed.
  • For instance, individuals with deficits in processing nouns and verbs show no activity in the affected area, while healthy individuals exhibit distinct neural activity, indicating the area's role in language processing.

Advantages and Limitations of Studying Brain Damage

  • A key advantage of studying brain damage is testing theories about the causal roles of specific brain areas in distinct cognitive tasks; however, finding subjects with such damage is challenging.
  • Additionally, related areas may also be affected by damage, complicating the localization of cognitive functions to specific regions.

Transcranial Magnetic Stimulation (TMS)

  • TMS involves using a coil placed near a targeted brain area to temporarily inhibit its function. This method allows researchers to observe changes in cognitive activities associated with that area.
  • There are two types of TMS: single-pulse TMS provides immediate feedback after stimulus presentation, while repeated TMS delivers multiple pulses to induce longer-lasting inhibition.

Effects and Limitations of TMS

  • Repeated pulses can lead to neuronal fatigue, causing temporary non-firing states that inhibit activity. While this method has advantages similar to neurophysiological studies, it is limited to surface areas of the brain.
  • One limitation is that activation or disruption may affect not only the targeted area but also adjacent regions, making it difficult to attribute changes solely to one location.

Drug-Induced Disruption for Cognitive Study

  • Specific drugs can be used to inhibit certain brain areas during cognitive tasks. Comparing performance between drugged and non-drugged subjects reveals insights into mental processes involved.
  • An example includes administering a drug affecting adrenal function within the hippocampus; this leads to impaired memory task performance due to disrupted hippocampal function.

Modeling as a Method for Understanding Cognition

  • The final method discussed involves creating computer models that simulate underlying mental representations and processes responsible for various human performances.
  • Two primary types of models are process models—illustrating sequences from input to output—and neural network models—representing interconnected neuron-like structures mimicking cognitive functions.

Understanding the Process Model in Cognition

Overview of Steinberg's Experiment

  • The discussion revisits the structure-process trade-off from the previous class, focusing on Steinberg's example of studying cognitive comparisons.
  • Subjects were tasked with remembering a list of items, which were later tested through probes to assess memory retrieval.
  • Steinberg proposed that searching for a target item in memory occurs via a serial process, which can be modeled to explain this cognitive function.

Steps in the Serial Processing Model

  • The experiment involves encoding a probe after subjects memorize a list. They then determine if the probe is present in that list.
  • Each item in memory is compared sequentially with the probe; decisions are made based on whether representations match or differ.
  • The model illustrates that even after finding a match (e.g., comparing 'three' with 'three'), processing continues until all items are checked.

Limitations of Traditional Process Models

  • While effective at explaining cognitive processes during comparison tasks, traditional models do not account for neural mechanisms involved.
  • These models focus primarily on input-output sequences and neglect underlying brain structures and processes essential for cognition.

Introduction to Neural Network Models

  • To address limitations, neural network models were developed, incorporating interconnected units beyond simple input-output systems.
  • These networks include hidden units (akin to brain neurons), allowing for more complex processing of information.

Functionality of Neural Networks

  • A simple feed-forward network structure is described, where inputs are processed through multiple hidden layers before reaching output layers.
  • Neurons within these networks can exhibit either excitatory or inhibitory responses based on encoded environmental representations.

Benefits of Neural Network Models

  • This model elucidates neural codes responsible for outputs and distinguishes between mental representations and corresponding brain states involved in processing.

Methods of Studying Cognition

Overview of Cognitive Study Techniques

  • The session concludes with a recap of various methods used to study cognition, emphasizing the importance of using multiple approaches to gain a comprehensive understanding.
  • Different methods have unique benefits and limitations; utilizing them together allows for a more complete picture of cognitive processes.
  • Four primary techniques are discussed: behavioral techniques focusing on accuracy and response time, and advanced imaging methods like EEG, PET, MRI, and optical imaging that localize brain activity during mental processes.
  • Causal methods are introduced which disrupt specific brain areas believed to be active during certain events, providing insights into their functions.
  • Modeling techniques involve creating computer simulations that mimic brain processes, allowing researchers to explore outcomes without directly studying the brain itself.