Lesson 4 - Physiology and Psychophysics Flashcards
What is the main finding of Franz Joseph Gall? When did he start his observations?
Childhood findings: his classmates who had large, bulging eyes were able to memorize verbal material
Adult Neuroanatomist Ambition: he found modularity and localization of brain functions
• Developed the 1st cohesive ideas about phrenology (empirically discovered)
How was phrenology first called?
• At first it was named Organology because it studied the organs of the brain
What technique did Gall use to decipher the magnitude of one’s faculties?
Used cranioscopy to decipher the magnitude of one’s faculties
• Carnioscopy: Faculties of the mind (acting upon and transforming information) are not equally developed among all people
• Well-developed: bump
• Underdeveloped: indent on skull
How many organs did the brain have according to Gall? How many were shared with other species?
Suggested that the brain was separated in 27 separate organs, each responsible for different functions of the mind
• 19 were shared with other species
• 8 were specific to humans
What was the work of Johann Gaspar Spurzheim about?
Saw organology as an opportunity to advance his career
Parted ways with Gall in 1813, and he developed phrenology
• Spurzheim became a popular writer and lecturer
• The public was interested in phrenology
• Mental muscle approach: if you are lacking in one area you can train it
Will be less and less scientifically proven, as more research will suggest that they were not correct
Who made a show from phrenology? How?
The Psychograph was patented in 1905 by Henry Lavery and was used in department stores and theatre lobbies during the great depression
• Measured skull size and indicated the person’s personality in 5 mins
How was phrenology introduced to the USA?
Came for the first time in the USA in 1820, with a lecture by John Collins Warren to the Massachusetts Medical Society Americans were interested in: • What works • What helps What is practical
Who made a business out of phrenology?
The Fowler brothers developped a successful business
• Provided phrenological consultations
• Sold busts for 1$ each
Summarize the work of Pierre Flourens about phrenology
Attempted to scientifically disprove phrenology in 1815
• Using Ablation/Extirpation (destroying parts of the brain to see the behavioural consequences resulting)
• Investigated localized functions in the brain
His findings were contrary to the phrenologists
Observations:
• Much of the brain works as a single unit
• The function that was lost to an ablation could be regained later in most cases
• Challenged Gall’s view that personality could be attributed to the size/shape of the brain
• Behaviours could be tested but not personality
• Never really saw different brain sizes, and if there were there was no incidence on the brain’s function
• Indents on the skull did not influence functions unless it was due to an accident
Describe the results of Flourens’ ablation studies
Ablation studies: Experiments with pigeons • Vestibular system removed impaired • Sense of balance • Spatial orientation • Coordinating movement with balance • Cerebellum removed • Muscular coordination • Sense of equilibrium • Medulla oblongata • Death of the animal • Mid Brain • Visual and auditory reflexes
Describe Paul Broca’s work with “Tan”
French Physician treating a man who was only capable of saying “Tan”
• Dissected his brain and found a lesion in the left hemisphere caused by neurosyphilis
Flourens was not entirely correct either
Clinical method:
• Observe someone with a brain disorder (since we cannot dissect live humans)
• Posthumous examination of brain structures allowed to detect damaged areas assumed to be responsible for the behavioural conditions that existed before the person died
What is Broca’s area?
Broca’s area
Region responsible for speech production
• Lesion: Broca’s aphasia
• Understands speech, but unable to respond intelligibly
What is craniometry? Who invented it?
Craniometry: determine the relationship between brain size and intelligence
• Larger = more intelligent
• Indicated that men are + intelligent than women
Paul Broca
What is Wernicke’s area?
Wernicke’s Area (10 yrs later)
Similar problem to Broca’s aphasia
• People were able to speak, but not to comprehend language
• Wernicke’s aphasia
Describe Phineas Gage’s case and what it allowed researchers to discover
Broca and Wernicke showed that although there is localization of function in certain regions, there is also some distribution
• A railroad accident will give researchers insight into the role of the frontal lobe and its connection with emotion and personality
• Phineas Gage was a foreman working on a railroad
• Iron rod exploded through his skull (left side)
• Survived but began acting differently
• Used profanity
• Unable to maintain a job or a relationship
• Difficult time making and following plans
• Became irritable
• Damage of the frontal lobe: specifically responsible for executive functioning (planning, emotional regulation, delaying gratification)
Describe Eduard Hitzig’s experiments with soldiers
Danish-Prussian war of 1863
• Eduard Hitzig worked with soldiers wounded in battle
• Soldiers had parts of their skull removed with exposed brain visible
• Applied wires from a battery to the cortex
• Observed involuntary reactions, twitching and screaming
Describe Gustave Fritsch’s work with Hitzig
In 1870 Gustave Fritsch joined Hitzig
They removed part of live dogs’ skulls to expose the cortex
• Electrical stimulation of the cortex revealed that:
• The cortex is not insensitive
• Muscular movements on the opposite side of the body are elicited, thus discovering the motor cortex and contra-laterality
• What would turn out later to be the sensory cortex was also discovered
Describe the work of David Ferrier, following Fritsch and Hitzig’s steps
David Ferrier (1843-1928)
Used similar methodology as Fristch and Hitzig
• Used non-human primates to produce a more articulate map of the cortex
• Able to provoke:
• Movement of one finger
• Twitch of an eyelid
What aspect of Descartes’ reflex action theory will be re-evaluated?
Descartes believed that bodies worked like machines and that the nerves were hollow tubes
• This perspective will be re-evaluated
• Is there no directionality/specificity?
Describe David Hartley’s work regarding associationism
Physician, became known as the father of associationism
Influenced by: Locke and Newton
• Mind/body connection contended that a physiological response was needed to engage the physical mind
• Synthesized Newton’s conception of nerve transmission (which stated that nerves were activated with vibration) with versions of empiricism
• Nerves are solid, not hollow
• When a vibration starts in the nerves, the law of inertia maintains it
• Nerve vibration was also responsible for the experience of pleasure and pain (hedonistic)
• Excessive vibration = pain, mild = pleasure
• Suggests that the law of association (associating actions with pleasure and pain) can be applied to behaviour to describe how involuntary behaviour can lead to voluntary behaviour
Describe the work of Luigi Galvani
Italian physician and physicists studied the electrical nature of nerve impulses
• Found that electricity could generate a muscular contraction (dead frog’s leg)
• Tried to replicate this finding multiple times by hanging frog legs on a copper wire during a thunderstorm or stimulating the muscles by touching the nerves with different metals
• Believed that animal tissue contained “animal electricity”
What is Hartley’s law of association?
• Suggests that the law of association (associating actions with pleasure and pain) can be applied to behaviour to describe how involuntary behaviour can lead to voluntary behaviour
Describe the contribution of Alessandro Volta on Galvani’s work
Proved that electricity did not emerge from the animal tissue itself, but from the effect produced by the contact of 2 different metals
What did Giovanni Aldini do with his uncle Galvani’s work?
Travelled around Europe to make crowds watch him apply electrical stimulation to dead animals (cows heads) (1802)
“Galvanized” the corpse of George Foster, a man who had been executed for murdering his wife and child
• Electroshocked the face and rectum, making the body twitch
• Inspired Mary Shelley to write Frankenstein
Summarize the Bell-Magendie Law’s main finding
Charles Bell 91774-1842) and François Magendie (1783-1855) demonstrated the sensory nerves enter the dorsal roots of the spinal cord and motor nerves emerge from the ventral roots
Nerve physiology can be divided into:
• Sensory functions
• Motor functions
What did Charles Bell contribute to the Bell-Magendie Law?
Stimulation of motor nerves - results in movement of muscle tissue
Dissection of dead animals could only give info on motor function, not sensory
What did François Magendie contribute to the Bell-Magendie Law
Used live puppies (to fill Bell’s gap)
Stimulation of anterior portion of spinal cord results in movement (motor neurons)
Stimulation of posterior results in pain (sensory neurons)
Johannes Müller expanded on the Bell-Magendie Law, how?
Expanded on Bell-Magendie’s findings by demonstrating more specificity to sensory nerves
• Each of the 5 types of sensory nerves (5 senses) has its own energy and results in a characteristic sensation regardless of the stimulation that activated it (ex: rubbing eye hard makes us see flashes of light even though our eyes are closed)
• Therefore, each sensory system is maximally sensitive to a certain type of stimuli
• Eye - light waves
• Ears - Sound waves
• Touch - temperature/texture
• Taste and smell - chemicals
• Our senses being adequately stimulated allows us to bring all the stimuli together and creating an experience of the world
Was Müller an empiricist or rationalist?
Although Müller’s work was empirical, he underlined the importance of using reason and thought to make sense of the world
Briefly describe Hermann von Helmholtz’s contribution
One of the greatest scientists of the 19th century
• Prolific researcher in physics and physiology
• Instrumental contribution to psychology, specifically metabolism and vision
• Emphasized mechanism and determinism
• Fought against vitalism
• Assumed human sense organs functioned like machines
Explain Helmholtz’s principle of conservation of energy
Researched metabolic processes in frogs
Allowed him to extend the principle of conservation of energy to all living things
• Energy within a system:
• Is constant
• Cannot be added or subtractedCan be transformed from one thing to another (ex: energy taken in = energy expended by organism)
Explain Helmholtz’s materialist perspective
- Materialist perspective: extended Newton’s Law to living organisms
* By this perspective, nothing was unmeasurable
* Perceptions and interactions with the environment were physical
How did Holmholtz measure nerve conduction?
• Measured the response time after stimulating the nerve in different places
• Found that neural impulses travel at a rate of 90 feet per second
To measure the human nerve impulse, he measured the reaction time
• Reaction time: amount of time taken to respond to a specific stimulus
• The location of the stimulus made a difference in response time
• Closer to thigh = shorter response time
• Calculated that the rate was between 165 and 196 ft/sec (pretty slow - probably because he use reaction times to base his measures, which tend to be different between people)
Explain Helmholtz’s theory of perception
According to Helmholtz,
• Sensations = raw elements of experience
• Perceptions = assigned meaning to the sensation
• Transformation from sensation to perception requires unconscious inference of past experience
Suggested that most of Kant’s categories of thought could be explained by experience
We perceive space and time because we have experienced them
• Suggested that someone who had been blind all their life and were suddenly able to see would have to learn how to perceive
What is Helmholtz’s ophtalmoscope?
Machine which allows doctors and researchers to look at the retina
• Charles Babbage had come up with a similar design, but hadn’t publicized his findings, so von Helmoltz now gets the credit
Ophthalmoscope allowed access to the posterior portion of the eye
Describe Helmholtz’s trichromatic theory of colour
Suggested that there were 3 types of colour receptors corresponding to the 3 primary additive colours: red, green and blue
• Also known as Young-Helmholtz theory of colour
• Firing receptors in various combinations results in subjective colour experiences corresponding to various wavelengths of light
They used colour matching experiments where participants had to reproduce test colours using a set of given colours
• If the participants only had 2 colours, they could never match the actual test (needed 3)
Describe Helmholtz’s resonance theory of hearing
Proposed a resonance place theory of auditory perception:
• Pitches of sound are determined by where along the basilar membrane the most vibration is occurring in response to a sound vibration
The basilar membrane is made up of different sized hair cells
• Showed that these receptors are able to vibrate based on incoming sound - a certain frequency will cause the appropriate receptors to vibrate and hence we can experience the sound
Who challenged Helmholtz’s tri-chromatic theory?
Edwald Hering (1834-1918) • Proposed an alternative theory of colour vision • Noted that some colours do not blend - perception of yellow could not be explained by the mixing inputs from the 3 receptors discussed by Helmholtz
Describe Hering’s Opponent Process Theory
Hering suggested that there are receptors in the eye which a linked together
• They respond in an opponent process manner, red-green, blue-yellow, and black-white
Summary of Opponent Process Theory
When one of the receptors is fatigued, the opposing receptor will be engaged
• The pairings: red-green, blue-yellow, and black-white
• Activation of one inhibits the other
• Extended activation of one will cause the inhibited colour to activate when you move away from the original stimulus
Between Helmholtz and Hering, who was correct regarding vision?
Who Was Correct?
• Helmholtz theory is correct at the retina level
• Neural processes further up the system work in Hering’s opponent process manner
Decribe the work of Christine Ladd-Franklin
Proposed a theory of colour vision (1892)
• Based on evolutionary theory and evolution of the physiology of the system
• Ability to perceive colour combinations evolved over time
• Achromatic vision (B&W) came first, then blue-yellow sensitivity, and finally red-green sensitivity
How did Johan Friedrich Herbart took Kant’s opinion about psychology needing to be mathematical further?
Took Kant’s opinion that psychology needed to be mathematical to be a true science
• Proposed that numbers could be assigned to psychological experiences of different intensities
• The study of these intensities and the resulting responses will be discussed in terms of psychophysics
Describe Herbart’s Psychic Mechanics
Believed that ideas had a force or energy of their own and the laws of association were not necessary to bind them
Ideas: had a force/energy of their own, attempt to gain expression in consciousness and compete with each other to do so
Apperceptive mass: group of compatible ideas that are in consciousness to which we are attending in a given moment; incompatible ideas outside the appecerptive mass will be repressed by the powers of the ideas in the mass
Limen: threshold between conscious and unconscious
Describe Ernst Heinrich Weber’s interests
Rise of experimental psychology
Interested in kinesthesis
• Ability to detect changes in body position and movements without relying on information from the 5 senses
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Describe Weber’s concept of 2-point sensitivity
Two-Point sensitivity
Investigated the sense of touch using a two-point caliper
• More sensitive region = closer the points of the caliper can be while still being detected as 2 individual points
• Insensitive = caliper needs to be far apart to be detected
Discovered that the sense of touch was constituted of 3 senses:
• Pressure
• Temperature
• Pain
Describe Weber’s concept of Just Noticeable Difference. How did he discover this?
Just Noticeable Difference (JND)
Smallest amount of change required to be detected as a change in stimulus
• Weight discrimination experiments
• Standard and comparison weight
• Were allowed to let their hands on the table or lift them
The weight of the standard stimulus influenced the JND
• Heavier standard stimulus = higher JND
Easier to detect difference when allowed to handle the weights vs when they had to keep their hands on the table
• JND is a constant fraction of the original weight of the stimulus
1/40 for the lifted weights and 1/30 for the non-lifted weights
Describe Weber’s law
the amount of change necessary to notice a difference is a constant fraction relating to the stimuli
• First quantitative law in psychology
• Clear method for investigating the relation between the body (stimulus) and the mind (sensation)
Describe Gustave Theodor Fechner’s interests
Physician, physicist and researcher
Interested in mind/body connection
• Added maths to Weber’s work
Goals:
• Measure perceptions in the same way we can measure temperature
• Solve the mind/body problem that was plaguing the times
Describe psychophysics
• Psychophysics: branch of study involving physical measurements and quantification of psychological phenomena
Describe Fechner’s threshold theory
To further elaborate on the ability to consciously perceive stimuli, Fechner would have to address:
• Detection issues: at what intensity a stimulus could be perceived
• The stimulus must reach a threshold before it is consciously detected
• Fechner assumed that the intensity started at 0 or undetectable
• Signal detection: presenting the stimulus at different intensities all the while asking if the participant could perceive it
Absolute Threshold: lowest intensity at which a stimulus can be detected
Signal is perceived at a certain intensity 50% of the time
Fechner was able to quantify this for different senses
Describe the 3 methods Fechner used to quantify the difference threshold (AKA JND)
- Method of Limits
A stimulus changes in ascending or descending order
• Contrast augments from 1% to 10% gradually, and researcher asks when a difference is noted
• Contrast can also be descending- Method of Constant Stimuli
Stimuli are shown in a randomized manner - Method of Adjustment
Allows the participant to be in charge of the change in intensity
- Method of Constant Stimuli
