Biological Theories and Perspectives
Chapter 1 Biological Theories and Perspectives
🧭 Overview
🧠 One-sentence thesis
Early philosophical debates about innate versus learned knowledge and physiological discoveries about brain localization laid the foundation for psychology to emerge as an experimental science focused on understanding how mental processes and adaptive behaviors promote survival.
📌 Key points (3–5)
- Philosophical roots: Psychology originated from debates between nativism (knowledge is innate/inherited) and empiricism (knowledge comes from experience), with dualism proposing that mind and body are separate but interact.
- Physiological breakthroughs: Brain research revealed that specific areas control particular functions (e.g., Broca's area for speech, frontal lobe for emotion regulation), weakening dualism and strengthening the mind-body connection.
- Structuralism vs. functionalism: Structuralism tried to break conscious experience into basic elements through introspection; functionalism emphasized the adaptive purpose of mental processes in natural settings.
- Evolutionary foundation: Darwin's natural selection and Galton's heredity research showed that both biological and behavioral adaptations are passed down to ensure survival and reproduction.
- Common confusion: Structuralism and functionalism both studied consciousness, but structuralism focused on what experiences are made of (elements), while functionalism focused on why they exist (adaptive function).
🏛️ Philosophical foundations of psychology
🏛️ From spirits to natural causes
- Ancient belief: Spirits or God controlled health and illness—health was a gift, illness a punishment.
- Hippocrates's shift: Introduced the idea that illness has natural causes requiring natural treatment, not exorcisms or charms.
- Proposed the four humors theory (bile, phlegm, blood) to explain physical and psychological traits.
- Established early medical ethics: "first, do no harm" (Hippocratic oath).
- Example: Instead of treating fever as divine punishment, Hippocrates looked for bodily imbalances.
🧠 Nativism: knowledge is innate
Nativism: The view that we are born with some knowledge because the life we lived before knew it (associated with Plato).
- Plato theorized life exists in a cycle (like reincarnation); knowledge from a previous life carries into the new mind.
- This implies certain types of knowledge are innate rather than learned.
- Don't confuse: Nativism is about inherited knowledge across lives, not just genetic traits.
📖 Philosophical empiricism: knowledge from experience
Philosophical empiricism: The theory that experiences create knowledge and learning occurs through observation (associated with Aristotle).
- Aristotle proposed the tabula rasa (blank slate): at birth, the mind has no knowledge.
- Knowledge is built entirely from sensory experiences and observation.
- Example: A child learns "hot" by touching a warm object, not by being born knowing it.
🔗 Dualism: mind and body interact
Dualism: The concept that the mind and body are distinct from each other but interact and influence each other bidirectionally (proposed by René Descartes).
- Descartes viewed the body as a machine governed by physics and chemistry.
- Mind = thought (mental element); body = movement, reproduction (physical element).
- He believed nerves were hollow tubes through which "animal spirits" flowed in response to external stimuli.
- Why it matters: Inspired exploration of the nervous system and how external stimuli influence the body.
🪞 John Locke: sensation and reflection
- Built on Descartes's doctrine of ideas and Aristotle's tabula rasa.
- Knowledge comes from:
- Sensations (raw sensory input).
- Reflections (meanings given to sensations based on past experiences).
- Reflection follows sensory experiences immediately and accumulates over time.
- Example: You taste a new fruit; you reflect on past fruit experiences to decide if you like it.
- Why perceptions vary: Tangible qualities (weight, dimension) are consistent; complex qualities (taste, smell, color) vary person-to-person because each person adds their own accumulated knowledge.
🧬 Physiology connects mind and body
🧬 Early brain mapping
- Johannes Müller (1801–1858): Sparked experimental research on the nervous system's role in behavior.
- Researchers discovered:
- Stimulating specific brain areas produces reflexive responses.
- Damaging a brain area leads to loss of response.
- Clinical brain research (autopsies, electrical stimulation) began in hospitals.
🧩 Franz Joseph Gall and phrenology
- Gall's contributions:
- Discovered white (myelinated) and gray (unmyelinated) matter.
- Showed nerve connections cross to the opposite side of the spinal cord.
- Proposed that larger brains = advanced mental abilities (early idea of atrophy).
- Asserted different brain areas are responsible for particular mental activities.
- Phrenology: The (failed) theory that skull bumps and dents reflect brain shape and mental abilities.
- Temporarily used to screen employees, assess intelligence, identify emotional problems.
- Discounted when researchers found skull shape ≠ brain shape, and brain maps were inaccurate.
- Don't confuse: Phrenology was wrong, but the core idea—brain localization—was correct.
🗣️ Language areas: Broca and Wernicke
| Area | Location | Function | Discoverer |
|---|---|---|---|
| Broca's area | Lower left frontal cortex | Producing spoken language | Paul Broca (1824–1880) |
| Wernicke's area | Left temporal cortex | Comprehending language | Carl Wernicke (1848–1905) |
- Broca's patient: Could understand language and use gestures but could not form words/sentences. Autopsy revealed a tumor in the lower left frontal cortex.
- Aphasia: Difficulty producing or comprehending language due to damage in Broca's or Wernicke's area.
- Example: Damage to Broca's area → person understands "close the door" but cannot say it aloud.
🧠 Phineas Gage: frontal lobe and emotion
- 1848 accident: A 3-foot, 13-pound rod shot through Gage's lower left jaw and out the top of his head.
- Before: Quiet, well-mannered, conscientious, hard-working.
- After: Easily irritable, indecisive, irresponsible, struggled with rational decisions and emotion regulation.
- Discovery: First case showing the frontal lobe's role in emotional regulation, planning, and decision-making.
- Why it matters: Demonstrated that specific brain areas influence observable behaviors, weakening the dualism perspective.
🔬 Structuralism and functionalism
🔬 Structuralism: breaking down consciousness
Structuralism: The science focused on defining the mind-body connection as sensory threshold responses to external stimuli; aimed to identify the basic elements of conscious experience.
- Key figures: Wilhelm Wundt, Hermann von Helmholtz, Edward Titchener.
- Wilhelm Wundt (1832–1920):
- Taught the first formal university-level psychology class.
- Established the first academic psychology laboratory (1879).
- Focused on thoughts and feelings of conscious experiences.
- Hermann von Helmholtz (1821–1894): Created methods to test nerve impulses, explore thresholds, and measure reaction times.
- Edward Titchener (1867–1927): Developed methods to describe and measure conscious experiences; focused on identifying mental elements or qualities.
- Introspection: The method of having individuals narrate their perception of an experience.
- Example: Describing the experience of eating a crisp red apple in your own words.
- Why it failed: Interpretations of experiences were inconsistent; defining consciousness by elements proved impossible.
🌱 Functionalism: purpose of consciousness
Functionalism: The science asserting that each mental element has a functional role or purpose in experience; conscious experience promotes survival through learning and instinctive reactions.
- Key figures: William James, John Dewey, John James Rowland Angell.
- William James (1842–1910): Emphasized the individual interacting in the natural setting; consciousness is adaptive.
- John Dewey (1859–1952): Highlighted the effect of experience on the organism as a reaction to stimulus; focused on what is learned and how it influences future experiences.
- John James Rowland Angell (1869–1949): Proposed psychology should explore how the mind influences adaptive behaviors; emphasized the relationship between mental processes and adaptive behaviors as the individual interacts in the environment.
- Why Wundt and Titchener disagreed: Functionalism was not experimental psychology; it incorporated evolutionary themes.
- Don't confuse: Both studied consciousness, but structuralism = what (elements), functionalism = why (adaptive purpose).
🔄 Structuralism vs. functionalism comparison
| Aspect | Structuralism | Functionalism |
|---|---|---|
| Focus | Breaking experiences into basic elements | Purpose/function of mental processes |
| Method | Introspection, experimental | Observation in natural settings, less experimental |
| Goal | Identify mental qualities | Understand how mind promotes survival/adaptation |
| Outcome | Failed due to inconsistent interpretations | Established foundation for later schools of thought |
🧬 Evolutionary perspective
🧬 Natural selection and adaptation
Natural selection: The preservation of mental and behavioral adaptations that ensure survival of the organism and the species.
- Charles Darwin (1809–1882): Proposed that organisms adapt biologically and behaviorally to survive and reproduce.
- Adaptation examples:
- Changes in food consumption patterns to match availability.
- Changes in pigment color to blend into the environment.
- Adaptations that help survival and reproduction are passed to offspring through heredity.
- Sometimes adaptations lead to a new species entirely.
- Adaptation examples:
- Evolutionary psychology: Assumes human behavior is handed down through millions of years of natural selection.
- Behaviors harmful today (stress response, aggression, preference for high-fat foods) were once adaptive.
- Example: Quick stress response helped ancestors escape danger; aggression helped secure food and mates; high-fat preference provided calories when food was scarce.
🧬 Creationism vs. evolution
- Creationism: God created all living things.
- Darwin's challenge: Through adaptation to environmental demands, species evolved into distinctively new species.
- Darwin's research was detailed, scientific, and observational—widely accepted but also deeply rejected.
- Functional psychology adopted Darwin's observational methods and adaptation findings.
🧬 Francis Galton: heredity and eugenics
- Francis Galton (1822–1911): Explored heredity, especially in accomplished circles.
- Eugenics: The science proposing that people could evolve to their greatest potential by selective breeding.
- Attraction from evolutionary perspective:
- People are naturally attracted to genetic qualities that enable offspring to survive and reproduce.
- Universally attractive traits: Physical beauty, high testosterone, youth, fertility.
- Masculine features: Associated with testosterone and strength → increased mate selection and offspring survival.
- Feminine features: Immature features associated with estrogen, nurturing, fertility → desirable for reproduction.
- Shape preferences: Women prefer inverted triangle (broad shoulders, narrow waist); men prefer hourglass (broad shoulders, small waist, broad hips).
- Galton's contribution to psychology: Introduced scientific methods for quantifying and analyzing psychological traits (individual differences).
🧬 Why evolutionary psychology matters
- All conscious and unconscious sensations and responses are relevant to survival.
- Darwin: Organisms actively promote survival by adapting to environmental changes.
- Galton: Methodology for studying human behaviors scientifically.
- Example: Jealousy may aid reproduction by ensuring mate fidelity and offspring survival.