History of Nature-Nurture Debate

Plato Rationalist- serious contemplation can derive rational answers knowledge is innate gave rise to introspection Aristotle Empiricist- observe external causes of behavior gave rise to materialism- experience is the source of knowledge History of Nature-Nurture Debate

how does the “soul/mind” give rise to memory, sensation, movement, etc. where is the “soul/mind” located

Decartes (1596-1650) was a Rationalist Proponent of Dualism: body (material) and soul (immaterial) are independent Body acts according to laws of physics Soul cannot be studied (source of knowledge) mechanistic view (e.g., reflexes) pineal gland as the interface between soul and body “Mind-Body Problem”

Hobbes • Hobbes (1588-1679) was an Empiricist • Proponent of Monism: all we are can be explained by physical characteristics • Led to British Empiricists (18th Century)

British Empiricists • Supported method of observation to study mental processing • John Locke - “Tabula Rasa” • all thought can be explained in terms of sensory experience

Industrial Revolution • Asylums became “theatre” for the rich (e.g. Bedlam (Bethlem and Maudesley)) • Un-scientific treatments proposed e.g. • MHP is excess of blood, therefore • Blood letting • Other “treatments”: • Fright • Forced vomiting

Bedlam

Phrenology: Franz Gall (1758-1828)

cranioscopy

Mesmer • Magnets • "The workings of dilation and contraction of the vessels, on the liquor which they contain, is the cause of animal life."

Hyponosis

Towards Enlightenment:Humanitarianism and social revolution • Locke (late 1700’s) in UK proposed a “reasoning” argument for mental health problems • “madmen put wrong ideas together, and so make wrong propositions but argue reason right from them…” • Quaker movement in UK • started retreats for the vulnerable for rest and some mild work • Pinel (1745-1826) in France • In line with egalitarian ideals of the French Revolution, proposed a Social theory of vulnerability, e.g. • Those with MHP were normal people who should be approached with compassion, as their reasoning was affected by severe personal and social problems… • Added that institutionalising people “denying light and air” exacerbated their problems

Into the Victorian era • but social exclusion rather than humane interventions continued • J.S. Mill in 1859 warned of the danger to vulnerable people of being: • “in peril of a commission de lunatico, and of having their property taken away from them and given to their relatives” • Exacerbated by the Eugenic movement: • “Discredited theory ranked human groups with…white Europeans at the top and people dwelling in their conquered colonies at the bottom” SJ Gould • People with intellectual/physical disabilities or were mentally unwell were seen as “not fit” to fit in and, again, scapegoated • Fernauld “the feeble minded…[are] parasitic..never capable..most dangerous element in society”

Advances in understanding mental health (19c-20c) • A biological Approach: • Kraeplin (1856-1926) • Proposed chemical imbalance (e.g. in metabolism) as causal of MHP • Established systems of classification according to medical knowledge not social prejudice e.g. • E.g. dementia praecox (later schizophrenia) • Manic-depressive psychosis • Delusions & general paresis (general weakness) • Advances in identification and treatment made e.g. • syphilis is caused by germs, is transmitted, & can damage areas of brain, leading to delusions & general paresis • If treated early, does not lead to brain injury and MHP symptoms

Advances in understanding mental health (19c-20c) • A psychological Approach • “biological” symptoms of psychological distress (psychogenic) described by Neurologists and Physicians • Charcot (1825-1893) & Breuer (1842-1925) • A sub-group of adult patients with intermittent paralysis of limbs or loss of hearing could have episode triggered by precise discussion of early trauma • Foundations of psychoanalysis

Weber (1795-1878) • Weber studied perceptions of weight and tried to relate these to actual physical weight. • Weight is an objective physical property of objects. • The greater the weight, the greater the difference between a standard and comparison must be to be detectable. • Weber’s Law -- Just-noticeable difference (jnd) is a constant across sensory modalities.

Fechner (1801-1887) • Tried to relate physical properties to psychological sensations: • Related the objective to the subjective. • Fechner’s Law – each JND corresponds to one subjective unit of measure, with the relationship described mathematically. • Credited with founding psychophysics.

The Same Color?

Webber’s Law

Sensing the World Around Us • Absolute threshold • The smallest intensity of a stimulus that must be present for it to be detected

Contrast Sensitivity 0% 1% 2% 3% 4% Circle constant Background constant Just noticeable difference (JND) at 2%

Contrast Sensitivity 0% 1% 2% 3% 4% Backgrounddifferent thenboth halves Backgroundsame asright half Just noticeable difference (JND): 4% (top) and 2% (bottom)

Brightness versus intensity • standard light at fixed intensity • test light with adjustable intensity • adjust power of test until just begins to differ • just noticeable difference: JND

Brightness versus intensity Standard Test A just noticeable difference (JND) at 11W 1 W above standard

Forced-choice Response • A bit more rigorous • Q: brighter light on left or right?

Forced-choice Response • A bit more rigorous • Q: brighter light on left or right? • Analyse accuracy of response versus intensity of lights

Brightness depends on wavelength • Light 1: at one wavelength • Light 2: at different wavelength • Adjust power of second light until its brightness is the same as the first

Simultaneous brightness contrast:two squares of the same intensity

History of Nature-Nurture Debate