IB Psychology HL and SL Notes

HL Biological Approach to Understanding Behavior: The Brain and Behaviour

Assumes behavior has physiological origins (e.g., brain structure, neurotransmitters, hormones).
Bidirectional relationship: biology affects behavior, and behavior can influence biology.

Limitations:
- No cause-effect due to lack of variable manipulation.
- Low generalizability (based on individuals).
- Cannot be replicated.
- Pre-accident data often based on unreliable memories.
Triangulation:
- Data: Multiple sources of data.
- Method: Multiple methods.
- Researcher: Multiple researchers increase reliability.
- Theory: Multiple perspectives (biological, cognitive, sociocultural).

Localization: Specific functions in specific brain areas (e.g., hippocampus = memory).
Distributive processing: Many areas work together for complex tasks.
Plasticity: Brain structure changes with experience (e.g., dendritic branching).
- Rosenzweig et al. (1972): Enriched rat environments = thicker cortex.
- Maguire et al. (2000): London taxi drivers = larger hippocampi.

Neurons: Send messages via action potentials.
Neurotransmitters: Chemical messengers across synapses.
Synaptic Plasticity:
- LTP: Repeated use strengthens synapse.
- Pruning: Unused synapses removed.
Excitatory (e.g., acetylcholine), Inhibitory (e.g., GABA).
Memory Link:
- GABA: Important for working memory.
- Acetylcholine: Memory in the hippocampus.

Hormones:
- Adrenaline: Emotional memory (Cahill & McGaugh).
- Cortisol: Stress response.
- Oxytocin: Social bonding.
Pheromones:
- May affect human behavior (e.g., AND, EST), but research is limited and inconclusive.

Epigenetics: Environment affects gene expression.
Twin Studies:
- MZ twins show higher concordance rates than DZ, but not 100%.
Key Studies:
- Kendler et al. (2006): Depression is ~38% heritable.
- Caspi et al. (2003): 5-HTT gene affects depression risk after stress.

Natural selection: Behaviors evolve to aid survival/reproduction.
Social Competition Hypothesis (Price, 1994):
- Depression may reduce conflict after social defeat.
Pathogen Host Defense Hypothesis (Raison & Miller, 2012):
- Depression may help avoid infection; linked to immune system/inflammation.

Used when human research would be unethical or impractical.
Benefits:
- Shorter life spans.
- Controlled environments.
Studies:
- Rogers & Kesner (2003): ACh and memory in rats.
- LeDoux (1994): Amygdala and fear.
- Harlow: Attachment in monkeys.
Ethics:
- Regulated by laws (e.g., Animal Welfare Act, EU Directive).
Implications:
- Human behavior shaped by gene-environment interactions (e.g., Caspi & Cases studies on aggression).

Schema Theory is central to cognitive psychology and explains how we organize and interpret information.
Schemas are mental frameworks derived from prior experiences, which help us process new information efficiently.
They also influence our behavior and memory.

These are mental representations of knowledge based on experience. When new information comes in, it is processed by comparing it to existing schemas.
This makes our interactions with the world more predictable but can lead to biases or errors in judgment.

A type of schema related to sequences of events, often learned through cultural interactions.
Scripts guide our behavior in familiar contexts, like how to behave in a restaurant or how to conduct a meeting.

Schema theory was developed by Frederic Bartlett, who suggested that memory is not a passive process like recording a video; instead, it's reconstructive.
We interpret and organize memories based on schemas, and sometimes, we fill in gaps in memory with information that fits our expectations.

Bartlett conducted studies to investigate how people remember stories, especially when the stories were culturally unfamiliar.
He found that participants tended to distort the stories to align with their own cultural schemas. The stories were often shortened, details were added, and elements were changed to fit the participants' cultural expectations.
This highlighted how memory is shaped by prior knowledge and expectations.

Schema theory helps explain how memory works through three main stages:

Encoding: The process of transforming sensory information into a form that can be stored in memory.
Storage: Creating a biological trace of the encoded information, which may be consolidated (made stable) or lost over time.
Retrieval: Using the stored information in thinking, problem-solving, and decision-making.

Schemas influence each stage of memory:

At encoding, schemas determine how we interpret and organize new information.
At storage, schemas help categorize and simplify information, making it easier to retrieve.
At retrieval, schemas shape the way we recall information, potentially leading to distortions if we fit new information into pre-existing mental frameworks.

Stores:
- Sensory Memory: Brief storage of sensory input.
- Short-Term Memory (STM): Limited capacity (7±2 items), short duration (18 seconds), requires rehearsal for transfer to LTM.
- Long-Term Memory (LTM): Unlimited capacity and duration, stores information for extended periods.
Processes:
- Encoding: Sensory information is encoded into STM.
- Rehearsal: Repeating info in STM to transfer it to LTM.
- Retrieval: Accessing stored info from LTM.
Research Support:
- Milner's HM case: Support for separate STM and LTM.
- Glanzer & Cunitz (1966): Primacy & Recency effects show separate stores for STM and LTM.