Welcome to the Biological Area Core Studies!
Welcome! In this section of the OCR H569 specification, we dive into the fascinating world of the Biological Area. Have you ever wondered why you can resist a slice of chocolate cake when you are on a health kick, how your brain navigates a bustling city, or what happens if the two halves of your brain cannot speak to one another? Biological psychologists believe that every thought, feeling, and action has a physical, biological root.
Don't worry if brain biology seems intimidating at first. We will break down every concept step by step, look at the classic and contemporary studies, and highlight all the common exam pitfalls so you can ace your exam!
---1. Foundations of the Biological Area
Core Assumptions
The biological area operates on two foundational principles:
1. All psychological experiences are biological: Everything psychological (thoughts, emotions, and behaviour) has a physical origin rooted in biological mechanisms such as brain structures, neural networks, genetics, and neurochemistry (neurotransmitters and hormones).
2. Scientific and controlled methodology: Psychology should be studied scientifically using objective, controlled, and laboratory-based methods such as MRI (Magnetic Resonance Imaging), fMRI (functional Magnetic Resonance Imaging), and tachistoscopic presentations.
Quick Review: Think of the brain as the hardware of a computer. If you want to understand how a software program (behaviour) runs, you need to understand the computer chips and circuits (biology) executing it!
---2. Theme 1: Regions of the Brain
This theme looks at how specific jobs are assigned to specific parts of the brain (known as localisation of function) and how the two hemispheres interact (known as lateralisation).
Classic Study: Sperry (1968) — Hemisphere deconnection and unity in conscious awareness
Background & Aim:
In a typical human brain, the left and right cerebral hemispheres communicate instantly via a thick band of nerve fibres called the corpus callosum. To reduce severe, life-threatening epileptic seizures, some patients undergo surgery to cut this bridge (a commissurotomy). Sperry wanted to examine the behavioural and cognitive effects of this hemispheric disconnection and test how specialised each hemisphere is.
Sample:
11 split-brain patients who had undergone a full commissurotomy to treat severe epilepsy.
Apparatus & Procedure:
Sperry used a tachistoscope (a special projector/display device) to present visual stimuli to participants.
Participants sat facing a screen with a central fixation point. Images or words were flashed to either the Left Visual Field (LVF) or the Right Visual Field (RVF) for exactly 0.1 seconds (100 ms).
Why 0.1 seconds? This speed is too fast for the eye to move, ensuring the image only enters the intended visual field!
Understanding the Wiring (Contralateral Control):
• Right Visual Field (RVF) \(\rightarrow\) Sent to the Left Hemisphere (LH) \(\rightarrow\) Controls the Right hand and contains Language Centres (speech and writing).
• Left Visual Field (LVF) \(\rightarrow\) Sent to the Right Hemisphere (RH) \(\rightarrow\) Controls the Left hand and is Non-verbal / Silent (handles visuo-spatial tasks).
Key Findings:
1. Visual Tests:
• When a word/image was flashed to the RVF, the patient could easily name it out loud and write it down with their right hand.
• When a word/image was flashed to the LVF, the patient said they saw "nothing" or just a flash of light. However, they could easily reach out with their left hand and pick up or point to the correct object from behind a screen!
2. Dual Visual Presentation:
• If two words were flashed simultaneously (for example, "TEA" to the LVF and "CUP" to the RVF), the patient verbally said "CUP" (processed by the speaking Left Hemisphere), but their left hand reached out and picked up a tea-related item / spoon (controlled by the silent Right Hemisphere).
3. Tactile (Touch) Tests:
• An object placed in the right hand could be named verbally.
• An object placed in the left hand could not be named out loud, but could be identified and retrieved from a bag by touch using the left hand.
Conclusions:
Each hemisphere has separate memories, perceptions, and functions. The Left Hemisphere is dominant for language, speech, and analytical tasks, while the Right Hemisphere is non-verbal, capable of silent comprehension, spatial processing, and non-verbal recognition.
Common Examiner Pitfall to Avoid (Sperry):
Do not say: "The left eye connects to the right brain and the right eye connects to the left brain."
Correct fact: Both eyes see both visual fields! It is the Left Visual Field (LVF) of both eyes that projects to the Right Hemisphere, and the Right Visual Field (RVF) of both eyes that projects to the Left Hemisphere.
Key Takeaway for Sperry: The Left Hemisphere talks; the Right Hemisphere points!
---Contemporary Study: Casey et al. (2011) — Behavioral and neural correlates of delay of gratification 40 years later
Background & Aim:
Can your ability to resist temptation as a 4-year-old predict how your brain works when you are in your 40s? Casey et al. tracked participants who originally completed the famous Stanford Marshmallow Test to investigate if self-control is a stable personality trait over 40 years, and to identify the underlying brain mechanisms involved in impulse control.
Sample:
A longitudinal sample originally tested at age 4.
• Experiment 1: 59 participants (32 high delayers, 27 low delayers; now in their 40s) completing a computerized Go/No-Go task.
• Experiment 2: 27 participants (from Experiment 1) scanned using fMRI while completing the Go/No-Go task.
Procedure:
Participants performed a Go/No-Go task where they were told to press a button when they saw a specific target face ("Go") and withhold their response when a non-target face appeared ("No-Go"):
• Cool Task: Neutral facial expressions (e.g., neutral male vs. neutral female faces).
• Hot Task: Emotional, alluring facial expressions (e.g., happy faces vs. fearful/neutral faces), where the happy face acted as the enticing "hot" stimulus.
Key Findings:
1. Behavioural Results: Both high and low delayers performed similarly on "cool" tasks. However, in the hot task, low delayers made significantly more false alarms (pressing the button by mistake on "No-Go" trials when shown happy faces).
2. Neural / fMRI Results:
• Inferior Frontal Gyrus (Prefrontal Cortex): Showed greater activation in high delayers when successfully inhibiting a response (practising cognitive self-control).
• Ventral Striatum (Reward/Limbic System): Showed significantly elevated activation in low delayers when responding to alluring "hot" stimuli (happy faces).
Conclusions:
Delay of gratification is a remarkably stable individual trait across the lifespan. Impulse control relies on a delicate balance: top-down cognitive control from the inferior frontal gyrus working to suppress the bottom-up reward cravings of the ventral striatum.
Memory Trick for Casey et al.:
• Inferior Frontal Gyrus = Inhibition & Focus (The "Brakes")
• Ventral Striatum = Very Sweet reward (The "Gas Pedal")
3. Theme 2: Brain Plasticity
Historically, scientists thought the adult brain was fixed and unchangeable. Brain plasticity (or neuroplasticity) is the brain's ability to physically reorganise its structure and neural pathways in response to learning, practice, and environmental demands.
Contemporary Study: Maguire et al. (2000) — Navigation-related structural change in the hippocampi of taxi drivers
Background & Aim:
To qualify as a licensed London taxi driver, candidates must master "The Knowledge" — memorising thousands of streets, landmarks, and routes over years of training. Maguire et al. wanted to investigate whether this intense spatial navigation training would lead to structural changes (plasticity) in the human hippocampus.
Sample:
• Experimental Group: 16 healthy, right-handed, licensed male London taxi drivers (licensed for at least \(1.5\) years).
• Control Group: 50 healthy, right-handed non-taxi-driver males selected from an MRI database (matched for age range).
Method & Analysis:
Participants underwent structural MRI scans. The scans were analysed using two techniques:
1. Voxel-Based Morphometry (VBM): An automated computer technique that measured overall grey matter volume across the whole brain.
2. Pixel Counting: A precise 2D cross-sectional area measurement of hippocampal slices, carried out by a researcher who was "blind" to whether the scan belonged to a taxi driver or a control.
Key Findings:
• Posterior Hippocampus: Taxi drivers had significantly greater grey matter volume in the posterior hippocampus (both left and right, but especially the right posterior) compared to controls.
• Anterior Hippocampus: Non-taxi controls had greater grey matter volume in the anterior hippocampus than taxi drivers.
• Correlational Analysis: There was a significant positive correlation between the amount of time spent working as a taxi driver and the volume of grey matter in the right posterior hippocampus.
Conclusions:
The posterior hippocampus stores mental representations and spatial cognitive maps of the environment. The adult human brain can alter its physical structure (demonstrating neuroplasticity) in response to environmental demands and learning.
Common Examiner Pitfall to Avoid (Maguire et al.):
1. Location matters: Never write that taxi drivers simply had "a larger hippocampus". Be specific! They had greater volume in the posterior (back) region, while controls had greater volume in the anterior (front) region.
2. Cause vs. Correlation: Be careful with causal claims! Because this is a natural/quasi-experiment, we cannot strictly prove navigation caused hippocampal growth, although the positive correlation with years on the job strongly supports the plasticity hypothesis.
Key Takeaway for Maguire et al.: Learning "The Knowledge" physically reshapes the posterior hippocampus!
---Summary Checklist for Revision
Before sitting your exam, make sure you can answer these questions with confidence:
• Can you explain what happens when an image is shown to the Left Visual Field vs. the Right Visual Field in a split-brain patient (Sperry)?
• Can you name the two brain regions identified in Casey et al. and describe their functions in self-control?
• Can you state the specific hippocampal region that showed increased grey matter in London taxi drivers (Maguire et al.)?
• Can you explain how both Casey et al. and Maguire et al. use brain scanning technologies (fMRI vs. structural MRI) to investigate human behaviour?