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Psych 1XX3 Textbook Notes

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Once you’re done, bold the topic of the chapter in RED so that it is easy for others to navigate through this document. Thanks. 1) developmental psychology - Maria Salman is done 2) evolutionary psychology pg 27-50 Pakeezah evolutionary psych 50-67 Shivani (inclusive fitness, parent offspring conflict and concluding thoughts) 3) neuroscience Saba 4) sensory systems pg 98-118 Ritchie 4) sensory systems 119-134 Supriya 5) sensory systems pg 135-145 - peter 6)psychological disorders - Harleen 7) psychological treatment -nadia (start -pg211) + zehra (211 to end) Chapter 1 Developmental Psychology This branch of psychology is concerned with the entire lifespan of human beings. However, much of the research encountered is childhood development only because so many enormous and fundamental changes are concentrated in this period of our lives. Research methods with the long view Developmental psychologists may rely on the experimental method less so because of the complexity of development so controlling for extraneous variables is incredibly difficult and maybe even impossible as well as the fact that developmental change may be because of the simultaneous action of a large number of variables. The quasi-experiment is a more commonly used research method in developmental psychology. This method deals with the fact that we frequently cannot manipulate variables like age or gender so what we can do is group subjects based on their existing level of that variable. But by doing this we are randomly assigning subjects to conditions and we cant really do the same cause and effect. Instead, what we can do is correlational techniques or simply taking the world as we find it rather than try and manipulate variables. There are two basic questions that can be asked about development: Descriptive or normative research asks questions about how things normally change from age to age. Analytic research asks about the processes and variables that are responsible for the changes in abilities and needs from age to age. In both cases, the passage of time is an important variable. One of the research designs we can use is longitudinal design which is where we compare development ar different ages by following the same group of people across time, this is like a within subjects design. The good thing about this study is that we eliminate extraneous variables but it is time consuming and costly. There is also practice effect and cohort effect where your are reflecting your cohort not universal. Physiological Development At conception sperm and egg fuse Genetic Transmission: The human genome consists of 30,000 or so genes – a complete set of which is present in every cell in our bodies. The link between genotypes and phenotypes is indirect because genes do not directly determine observable traits but it is more like each gene controlling the production of a particular protein or enzyme that in turn regulates a biochemical sequence within the developing organism determining the traits that get expressed. Genes guide the biochemical processes that lead to observable traits, but so do many other factors . Some traits are more genetically heritable than others but no characteristic is entirely determined by genes. The cascade gene model suggests that the SRY gene is only one gene amongst many interacting genes that produce the sex of the individual and that both male and female factors contribute. Additional factors also contribute to a human’s sex phenotype for example in androgen insensitivity syndrome males may appear outwardly female but have male reproductive organs. Prenatal Development Once we make a zygote it is undergoing rapid cell division Less than half of all fertilized eggs survive beyond the first two weeks of conception Ten days after conception, the zygote attaches to the uterine wall and its now an embryo The embryo is made up fo undifferentiated stem cells that will soon begin to differentiate After 6 weeks of gestation we have gonads that aren’t sexually differentiated yet. A week later testes make androgens and ovarian developmental factors make estrogens. After two months we have a one inch fetus By 7 months we have a 16 inch fetus that can reflex, cry, breathe, and swallow Postnatal Development Motor Development à Infancy and Childhood Human infants don’t have many motor skills Rooting reflex à close in on whatever mouth finds and will suck. Majority of individuals develop according to orderly sequence of genetically determined biological growth processes known as maturation As infants mature more complex motor skills develop and purposeless behaviours may be abandoned Babies stop grabbing at 3-4 months of age Voluntarily grasp at 5 months and can grasp with thumbs and forefingers at 12 months. Sequence of most motor skills is universal Babies roll before they can sit unsupported, and crawl on all fours before they can walk. 90% of babies can walk by the time they are 15 months old. Once gross motor movements are mastered, baby can now focus on more fine motor skills. By age 2, a toddler can pull, push and dump objects. He can also pull of hats and socks, turn pages, scribble, stack, feed, toss or roll a ball, open cabinets, and walk backwards. By 3 and 4 we have developed most of the skills toss and catch, walk in a straightline….. By age 5 we can hop and jump, use a fork, dress, somersault…etc. By middle childhood most children are as coordinates as adults and continue to work on ther most important task: physical growth Physiological Development in Adolescence Adolescence begins with the onset of puberty à the period of sexual maturation during which a person can become capable of reproduction Puberty marks the second major hormonally driven set of physical changes in the human body ---first being in utero Puberty starts from signal of hypothalamus to pituitary gland. Pituitary gland releases gonadotrophic hormones Gonadotrophic hormones influence reproduction by stimulating dramatic growth and maturation of the reproductive organs and external genitalia In males onset of puberty is marked by increase in testosterone, enlargement of testes and penis, lengthening of vocal cords, body hair, and the ability to ejaculate. In females estrogen is released by the ovaries and stimulates the growth of breasts, widening of hips, growth of pubic and underarm hair, and beginning of menstruation Physiological Development in Middle Adulthood Physical abilities peak in mid twenties and then decline Decline that happens in reaction time, muscular strength, and cardiac output is more gradual. Aging leads to a decline in fertility because of decrease in the production of sex hormones. Females have this decline more where pregnancy changes decrease at 35 and menopause at around 50 Men experience a gradual decline in sperm count, speed of ejaculation, and erection strength Libido decreases with age because of decrease of testosterone Physiological Development in Older Adulthood Many physical abilities decline à the amount and intensity of physical activity that can be tolerated, fighting off life threatening diseases, immunosenescence (decline in immune function). Age related bad stuff can be fought off with moderate exercise à it can increase immune function, protect from chronic diseases, and reaction speed while driving, and then decrease general chances of mortality. Neural Development Prenatal Development of the Nervous System - nervous system starts developing about 3 weeks after conception with the formation of primitive neural tissue, known as neural plate. - Neural plate folds and closes to become neural tube – leads to development of brain and spinal cor - Lined with neural stem cells that give rise to cells of nervous system - Forebrain, midbrain, and hindbrain are visible after 28 days - Brain looks human 100 days after conception the sulc and gyri are formed after 7 months. Effect of Prenatal Environment Nutrition Proper formation of the neural tube is critical for development Neural tube defects are most common birth defect. If the tube fails to seal in the head end of embryo -à anencephaly, failure to develop cerebral cortex à fatal If tube fails to seal lower end à spina bifida à part of the spinal cord develops outside the spine. Can be symptomless to highly diabling -à paralysis and sensory loss Neural tube defects can be greaty reduced if mother consumes folic acid prior to conception Teratogens à an agent or factor that causes malfunction of an embryo Can affect at any poin during pregnancy The earlier a fetus is exposed, the more harmful For ex. Alcohol Fetal alcohol syndrome (FAS) --- alcohol enters fetal blood supply Severe maternal stress à depression Flu -à schizo Sensory Experience - The sensations experienced by the fetus drive the early development of complex sensory systems. - At birth, visual system is relatively immature - Foundations for a visual system develop even though womb is fairly devoid of visual stiulation - Prior to receiving visual information, neural pathways in the developing visual system are restructured and are higly organized - This occurs because of spontaneous patterned acitivty in the retina that helps to strengthen and organize the connectivity of the visual system. - Audtition is fairly mature at birth - Primary auditory components such as the cochlea have developed to near adult levels. - Sound of blood flowing, heathbeat etc. womb is very loud - External sounds are also audible to the fetus - Fetus receives chemical sensory information in the womb - Prenatal flavor experiences help drive post natal flavor experiences. Post natal Development of the Nervous system: Infancy and childhood Brain Development: Synaptic Development - first few months à rapid increase in number of synapses - increase in synaptic density increases throughout much of first year of life. - After one year and until about ten years synapses decrease via synaptic pruning Brain Development: Role of Experience - increase and decrease of synapses during development is thought to be necessary for sensory development. - If an individual is born without a certain sense than brain can make extra connections where it would have otherwise been pruned - Rats raised in an environment with more sensory stimulation are better at problem solving tasks. --- increasingly complex neurons with more dendritic space. Experience Expectant/ Experience Dependant - Receiving input from both eyes is experience expectant - Whether or not visual system and connections and structures develop typically is experience dependant. - Amblyopia – lazy eye where even if cataract is removed, vision is still disrupted. Brain Development: Implications for sensory development Vision - visual acuity of newborn 40 x worse than adult b/c of immature retina - between birth and 6 months there is a five fold increase in acuity, slow improvement to adult levels by 6 years of age - newbrons are colourblind, by 2 months they can see red, and by 3 months they can distinguish green and blue. Audition - the auditory system makes up for its lack of exposure to high frequencies by improving rapidly upon post natal experience. Olfaction - our olfactory system has innate sensitivities and preferences. Brain Development: Sensitive Periods - early life does seem to be a time of greater sensitivity to change but the period of sensitivity does not end but rather tails of gradually and so critical periods are more accurately called sensitice periods. Development of the Nervous System : Adolescence - another wave of synapse production and pruning - greatest changes occur in frontal lobe à responsible for self control, judgements, emotions, an d organization Development of the Nervous System: Adulthood - when neurons are created --- neurogenesis ( for a long time it was thought that this only happens in childhood) - adults can experience too however in discrete regions or in response to injury - plasticity can help adapt to change - use it or lose it Cognitive Development Infancy and Childhood: - Piaget saud that childrens thinking is different than adults and development involved major age related changes in intellectual capabilities Modern perspective on cognitive development: - human cognitive abilities unfold universally - development is more continuous than suggeste - infants are capable of more than what we give them credit for Adolescence - inkcrease in power of reason, reasoning is often self focused. Adulthood: - cognitive abilities can decline with afe - Fluid intelligence à speed and efficiency of intellectual processing ß slow down at 30s - Accumulated knowledge ß crystallised inteeligence , remains relatively stable over time and may even ncrease - Decline in fluid inteelifence is subject to individual Aging and memory: à variable à working and episodic memory is better in youngones but implicit memory is better in old ones --- required to recall meanfingul thigns 2 - Evolutionary Psychology: · Study of mind and behavior as a branch of evolutionary biology. · The Wedekind experiment on shirts worn by men: o Men wore odorless shirts 2 consecutive nights. When women smelled it, they liked the ones with which were genetically dissimilar while disliked the odor of genetically similar ones. o Women taking contraceptives, however, liked the ones with similar genetic makeup. o Couples who have similar genotype have an elevated likelihood of producing offspring with a weaker immune system. o Taking contraceptives puts women in an infertile psycho-physiological state in which their preferences no longer reflect the evolved strategy. · Concept of evolution : phylogeny is a pattern of divergence of species from common ancestors. · In darwin’s Galapagos finches: 1977 drought left only hard seeds behind leading to the survival of birds with larger beaks only as smaller birds couldn’t find softer seeds that were abundant before. · The theory of evolution by NS – 3 points: variation within natural populations o Offspring tend to resemble their parents o Young are produced in excess à more breeders · Adaptations : Daphnia à food for fish. o Phototactic – when the sun is visible in the sky, they stay closer to depths (don’t be seen) if there is a predator around but otherwise, closer to surface for nutrition. o Youngs born near the time when there were no predators – responded less to light in presence of predator fish. § Offspring born during the predator time – more sensitive to light o In such case, when no threat of predation: daphnia with phototactic genes less likely to survive during fish presence than without those genes. · Adaptation: our traits serve specific functions which increase our reproductivity overtime. · Functionality: adaptations are efficient as they lead to fitness but their purpose is harder to identify. · Functions of adaptations are inferred from their operations. o Falling from a height: human beings are more cautious when walking around heights not to fall, or else it will lead to death àweaker survival. · Adaptations aren’t perfect! Just work best in the given environment. · Mate choice and sexual jealousy · Sexual selection: form of NS o Competition among individuals of once sex over (intrasexual) access to the other sex and competition to capture other’s interest (intersexual) · Mate choice: liberty to chose who to mate with depending on the level of attractiveness o Male are more tempted to mate than females o Costly to female interms of time, energy, nurturing, feeding, without any males help whatsoever. o Men prefer younger women – because they can reproduce more. o Women prefer older men – someone who can take care of the child financially, and has fewer desires to mate with someone else. o Quality = fluctuating symmetry e.g. walking upright. Both legs the same length. Symmetry decreases overtime. o Healthier indv: 1 - can pass on healthier genes that increase survival o 2 – make better long-term mates as they stay around longer to help and support. o Women with lower hip2waist ratio are more fertile o Masculinity and femininity are cues to fertility and quality of an indv. o ovulating women tend to have stronger preferences for facial masculinity o short term preferences change during menstruation and shift to talent, physique, etc. but long term preferences remain unchanged. o Cuckoldry: longterm mate is lead to believe that another man’s children are his own o Infidelity (possibility that one parent has been tricked into caring for a non- genetic offspring): when 2 sexes are in danger of the other enjoying sexual intercourse with someone else outside their relationship or having a romantic relationship. o Men more prone to sexual jealousy while women more prone to romantic jealousy! · Kinship and Human affairs : · Social behavior: actions that affect the actor and the audience. · Eusocial behavior – found mostly in insects, bees, etc. minority reproduces and majority are sterile. (selfless genes?) only in species where repro indivs mate monogamously = only one mate = high +ve relatedness among progeny · Genetic relatedness (r): probability that the recipient does in fact carry copies of the gene promoting the helping behavior. · When 2 indivs are more likely than chance to be carrying similar genes – positively related. r >0 · Less likely than chance to carry the same genes (more likely to carry rival genes) = negatively related r <0 · Inclusive fitness theory: a way for accounting for evolution of social behavior by measuring the success of a gene promoting the behavior via its effects on its bearers and the recipients. Indirect(to the relative/recipient) and direct(to the actor) fitness. · Inclusive fitness : · Eusocial = r>0, +ve relatedness, one mate, monogamy. (Phenomenon found in organisms mating monogamously leading to high relatedness among the progeny) · B >c (benefits of helping are large relative to the costs) · In terms of homicide, we care more for kins and close relatives than for strangers as it increases our genetic pool. Individuals are also discriminative with respect to recepient of their affections. ● Family Violence: genetic relatedness is a predictor of co-operation as well as conflict. Victims and killers co residing (family) are more likely to be non genetic relatives than genetic relatives. ● homicides involving co-killers are more likely to involve genetic relatives than non genetic relatives. ● Step relatives: step children residing with step parents are more likely to be abused and ignored due to their decreased reproductive value to step parents. · Infanticide – killing of infants by parents · Filicide – killing of offpsrings. Decreases as they age. · Patricide: killing of parents by kids due to extrinsic factors. · Individuals are far more likely to kill their spouses and children who are genetically dissimilar. · Collaborating on a homicide is also done if 2 people are genetically similar. · Social Darwinism (Herbert spencer responsible – social darwinism’s claims are wrong): arose out of beliefs that NS was the survival of the fittest. o What is natural is not what is good, it is just what it is. o Successful genes are successful because they have survived. · Eugenics – practice that promotes the selection of desired traits through advanced tech and elimination of the undesirable ones e.g. genetic testing. · But, we cannot define undesirable traits. · Kin recognition : · Psychological mechanism that organism have to help determine how closely related they are to others. · Maternal-perinatal[around time of childbirth]-association – cue that the infant is their sibling if the mother takes care of it in the same household. · Co-residence duration gives younger siblings time to familiarize themselves with the older siblings. the longer they live together, the more likely they are to be related. · Incest aversion – aversion to mating with close relatives · Future couples reared together(in israel, communties called kibuttz) are less likely to have a successful relationship. as they grow up, they learn that they are not necessarily corelated with each other but they virtually never marry anyone from the same community as they take co residence as a kinship cue. · Those who have older-opp sex siblings, co-rez duration predicted their aversion to incest while those who had younger opp-sex siblings had a general aversion. · We find resembling opp-sex faces less sexually attractive than non resembling faces. Another cue will be PHONOTYPIC SIMILARITY(physical resemblence) i.e. more genetically close 2 individuals are, the more likely they tend to resemble each other. This is mostly because of the same genes and moreobver they are also reared in the similar environment and circumstances. · Parent-offspring conflict : · The policy that maximizes parental fitness differs from the one that maximizes siblings fitness. o If both siblings were to get equal share, it will increase both sibling’s fitness equally o If one was to get more than the other, it will decrease the parents possibility to increase their genetic pool in terms of reproduction because the other might get starved of the resources. o Second scenario decreases the overall probability of parents fitness. so according to the parent’s perspective, its most beneficial to divide the resources equally because it would increases the progeny’s fitness and parent itself will have most fitness in this case. ○ Nonetheless, children (progeny members) will always want to monopolize the resources because if their sibling is getting more fit, its not as much beneficial to them as it would be if they themselves were getting the resources. · Theory approves that NS acts on dependent young in such a way as to make them seek a little larger share of parentally controlled resources than the parent is selected to provide. · Maternal-fetal interaction is unstable because the fixation of each novel maternal or fetal adaptation creates a selection pressure on the other party to evolve counter-adaptations. Why doesn’t altruism exist here? ● An Evolutionary arms race: - Triver’s theory tell us that NS acts on dependent young in such a way that it make them seek a little bit bit larger share of parentally controlled resources than the parent is selected to provide. Offspring’s genes select to extract more parental resources than is optimal for parental fitness. ● Concluding thoughts: - Personality psych needs evolutionary theory to explain the diverse traits (which are largely heritable) , this demand analysis of NS. Abnormal psych needs evolutionary theory as well because we cant understand pathologies with confidence untill we understand what attributes are adaptations. Chapter 3: Neuroscience - Humans do not have direct experience of the world around them. - Our experiences in the world are actually a result of a series of events in the central nervous system which were set in motion by the stimuli in the environment. - Two types of questions should be asked about brain: o Structural o Functional - The brain and the spinal cord make the central nervous system (CNS). - The remaining nerve tissues in our body make the peripheral nervous system (PNS). - Brain weighs 3.0-3.5 pounds. Makes up 2% of body weight. Burns roughly 20% of our oxygen intake when we are at rest. - Each of the 100 billion neurons form synapses with other neurons resulting a thousand trillion different connections. - Neurons contain organelles. - Brain needs to be examined at different levels because too detailed examination may lead to loss of the big picture. Consciousness and awareness: - Rene Descartes believed that the seat of the soul was in the pineal gland and it affected control of body through the nerves. - Fundamental idea: it’s impossible for the mental state of a person to change without some physical change in his brain. Epilepsy and the Split Brain: - In severe epilepsy: seizure-causing activity begins in one hemisphere of the brain and spreads quickly the other hemisphere over the corpus callosum. - Corpus callosotomies were performed in the past to reduce the severity of the seizure. But this led to adverse effects on brain’s normal function. Divisions of the Nervous System: - Brain weighs about 1.3 kg in an adult and is within the skull - Spinal cord is within the vertebral column. - Types of fibres: o Efferent fibers: carry information from CNS to periphery of the body. o Afferent fibers: carry information to the CNS from periphery of the body. The Somatic and Autonomic Nervous Systems: - PNS is divided to two parts: o Somatic nervous system: Par that receives sensory information from the sensory organs and controls the voluntary movements of the muscles. o Autonomic nervous system: controls the things that happens outside of our conscious awareness and regulates the smooth muscles, the cardiac muscle, and allows for the glands to operate. Smooth muscle causes certain organs to contract. ANS is divided into two further parts: § Sympathetic division: involved with preparing the body for emergencies - “fight or flight” response. Increase in heart rate, dilation of the pupils, dilation of the internal structures of the lungs, inhibition of digestion and inhibition of the contraction of the bladder and the rectum. These results are general and cannot happen in isolation. Causes release of adrenaline from the adrenal gland. § Parasympathetic division: Opposite sympathetic. Slowing of heart, lowering bp, contraction of the pupils, increase in activity of the GI tract and secretion of digestive juices. The Neuron: - Contained in a volume of around 1400 ml in our brain. - A sort of cells such as a muscle or gland that are capable of receiving and responding to a nerve impulse are known as effectors. The Dendrite: - Dendrites bring together the impulses occurring across the many thousands of synapses to their final destination at the cell body. - Some neuron types have up to 200000 of these synapses but 100-10000 synapses per neuron is more typical. The Cell Body: - Small. Ranging from 4 microns up to 100 microns. - The axon exits the cell body from an elongated portion called axon hillock. The Axon: - White matter of the brain – myelinated axons - Trigeminal nerve: responsible for movement and sensation in the face and head contains about 150000 axonal info from skin, muscles and joints to the brain and another 10000 efferent fibers that control the muscles of the jaw and throat that allow us to bit, chew and swallow. Neuron Subtypes: - Sensory neurons: sensory information from the environment - Receptor cells: transduce the physical stimuli from outside into nerve impulses. - Effector neurons (motor neurons): activate muscles of the body, controlling movement. - Interneurons: between sensory and motor neurons. o Multipolar: multiple dendrites and only one axon. o Bipolar: only one dendrite and one axon. (usually sensory) o Unipolar: has a single process leaving the cell body which branches into dendrites and an axon. Relative Refractory Period: During hyperpolarization when the membrane is relatively difficult to excite and will not likely fire another action potential. Absolute refractory period: Sodium channels close and will not open again for a period of time. The Synapse: - Once the neurotransmitter has activated the receptors in the postsynaptic membrane, it must be prevented from triggering other unwanted effects at the postsynaptic site. Some neurotransmitters are inactivated by special enzymes that break them down into their constituent chemicals. Other neurotransmitters are reabsorbed into the pre- synaptic cell through reuptake. Astrocyte: a type of glial cell that send out processes that are wrapped around blood vessel in the brain or parts of the neuron. They transfer nutrients from the blood to the neuron when needed. Eloquent Cortex: consists of those areas where damage would lead to paralysis, loss of language ability or loss of sensory processing. Cerebrospinal Fluid: - Brain floats in CSF - Brain is only loosely attached to skull by filaments called arachnoid trabeculae. - CSF extends down to spinal cord. And into the centre of the brain through chambers known as ventricles. - 500 ml of fresh CSF is secreted into the ventricles every day. The Hindbrain: - Consists of two major divisions: o Myelencephelon : medulla o Metencephalon: cerebellum and pons. o Medulla, pons and midbrain are collectively referred to as the brainstem. The Midbrain: - Also known as mesencephalon - The cerebral aqueduct filled with CSF runs through the centre of the midbrain joining the third and fourth ventricles. The Forebrain: - Two major divisions: the telencephalon and diencephalon. - Telencephalon: consists of cerebral cortex. - Amygdala and hippocampus are known as limbic system. The Cerebral Cortex: - The two halves of cortex are separated by the medial longitudinal fissure. - The cortex is only about 3mm thick and differentiated into six layers. - Humans do not have the largest brains, dolphins and African elephants have bigger ones. - Some sub-cortical structures are known as the basal ganglia. - 200 million more neurons on the left side than the right. - About 25 percent of the cortex is dedicated to primary areas. - Areas outside of the primary projection areas are often termed association cortex. Chapter 4: Sensory Systems (Part 1 and 2) INTRODUCTION TO VISION · What are Sensory Systems? · Used to gather information from the outside world. · Simplified model of Vision: · Signal travels through optic nerve èLGN èSeparated into colour and movement info where It is processed separately · Sensory Systems have physical limitations · Example: Our visual systems respond to a narrow segment of electromagnetic spectrum, cannot see ultraviolet (very long wavelengths) or infrared (very short wavelengths) · These cannot be processed · Different for other species, birds like pigeons have more sensitive colour system for example. · There are blind spots in our visual fields, the brain processes this information about these areas, makes up what it believes should be there and is ‘pasted’ into our visual input. · These altercations that the brain makes of images are seen through illusions as well such as the Muller-Lyer Illusion. THE STIMULUS · Perceive light as an electromagnetic radiation that simulates photoreceptors · The ‘Visible Spectrum’ is the spectrum of wavelengths that our eyes are sensitive to. · This is approximately wavelengths of 360nm – 750nm · Characteristics of light are what determine the colours we perceive · Wavelength = Hue · Saturation + Brightness = Amplitude · Hue = physical dimension that corresponds most closely to wavelength of light, (simply, what we mean when we name a colour: blue, green, red etc..) · Saturation = purity of the colour, completely saturated colour is the truest version of that colour. Impure light (less saturated) è lots of wavelengths è grey colour · Brightness: = reflects the sum of responses of all photoreceptors, higher wavelength means brighter colour. THE EYE · External Layer is Sclera and Cornea · Sclera protects the eye · Cornea accounts for 80% of focusing power of the eye · Iris gives eye its colour, controls amount of light that enters eye · Lens responsible for almost the rest of the focusing power, accommodates itself (by bending) to bring images into focus. Flat lens for distant objects, rounder lens from muscle contractions for close distances. · Near sightedness / far sightedness is a result of and error where light being out of focus in front or behind the retina. (because of LENS) · Hyperopia (farsighted), can see far but not close distances. Result of image that falls BEHIND retina being blurred. · Myopia (nearsighted), can see near, but not far. Result of light being focused in FRONT of retina. · Length of eyeball, abnormal curvature of cornea, increased/decreased power of lens can also contribute to sight issues. · Retina: converts images to an electrical signal, also where rods and cones are found. · RODS: contain visual pigment that is highly sensitive delight and active during low light vision. Total loss of rods = only night blindness. · CONES: responsible for day vision, people who lose function in cones are legally blind · three types of cones, each sensitive to a different wavelength of light, as a result.. they are referred to as CHROMATIC · about 120 rods converge to a single ganglion cell, 6 cone to one ganglion cell. · 20 x more rods than cones, but in fovea, no rods are present. · Cones adapt faster in dark than rods because rod pigments are regenerated more slowly than cone pigment. · 1.5 million ganglion axons form optic nerve, run from back of eye through optic disk to the retina of the brain. · Since no photoreceptors in optic nerve, it is known as blindspot. IMAGE PROCESSING · Information from the right half of environment is processed in left half of brain and all information from the left half of environment is processed in right half of the brain. · LGN is major relay of all visual information allowing for conscious visual perception. · LGN contains six distinct layers of cells, each cell receives input from one eye and one of two types of ganglion cells (P or M). · P cells (parvocellular) convey info for colour, pattern , form, texture and depth. · M cells (magnocellular) convey information about movement. · Layers 1 and 2 receive input from M cells and 3-6 receive inputs from P cells. · Primary visual cortex is first part that is responsible of processing visual stimuli · The principal layer for visual inputs is Layer 4 · the visual system is organized into a number of functional modules that maintain a high level of organization. FEATURE DETECTORS · Hubel and Wiesel discovered the organization of primary visual cortex as they respond to bars of light. · Simple Cells respond to the bars of light · Complex cells are sensitive to the orientation of a bar as well as movement · Hypercomplex cells are sensitive to orientation, movement and length of a bar. FUNCTIONAL MODELS OF VISUAL CORTEX · Referred to as columnar organization · Cells above or below tend to share same properties EXTRA STRIATE CORTEX · Can be defined into two major streams · Dorsal (where) and ventral (what) streams · In primates, extrastriate cortex includes v2,v3,v4,v5. · V2 and V4 respond to a ‘what’ pathway · V2 is a major area that shares many properties similar to v1, tuned to simple properties such as orientation, spatial frequency and colour. · V4 responds selectively to colour and simple geometric shapes of a stimulus like squares and circles. · V3 considered to be part of dorsal stream, processes motion · V5 is perception of motion. EVOLUTION OF THE EYE · Believe that eye emerged from a proto eye, which only allowed organisms to tell the difference between light and dark at the time. · The spot gave these organisms survival advantage, · Cluster of spots combined together through evolution, formed a patch of photosensitive cells, similar to what jellyfish have today (flat eye). Colour and Depth Perception · Processing of colour begins in the retina · Colour processing is a complex process o Colour is a constant property of an object o Reflected lights determines the colour o Tremendous amount of variation in wavelengths o Our eyes correct for that so that we are able to perceive ONE unique wavelength Variations of Colour Vision · Humans are trichromats, so are bees and macaque monkeys · Bees are sensitive to UV light · Goldfish, pigeons, and, ducks have four types of receptors · NO OTHER ANIMALS ARE TRICHROMATS Colour Mixing · Additive: mixing lights o Red, green, blue · Subtractive: mixing pigments (paints) o Reflect some wavelengths, but absorb all others Theories of Colour Vision · Combination of all three primary colours: white · Theory: colour must depend on the existence of three receptors, each of which is sensitive to a different wavelength of light · Theory: there are receptors sensitive to red, green, and blue light · Young-Helmholtz Theory: o A short wavelength will strongly activate the short wavelength receptors, but only a weak activation of the other receptorsèperception of blue o Likewise for all other wavelengths · Afterimages · Simultaneous contrast: two colours side by side interact with each other and change our perception of them · Opponent Process Theory: (In module) Colour Processing In the Retina · Low res channel receives input from M-type ganglion cells that have a larger receptive field · High res channels receive input from P-type ganglion cells that have smaller receptive fields · P-typeè 80% of all ganglion cells o Visual detail and colour and brightness variation In the LGN · Information from the P-cells goes to the parvocellular cells in the LGN Primary Visual Cortex · Blobs: regions that have concentrations of “special colour cells” Color Blindness · Three Types o Protanopia o Deuteranopia o Tritanopia · Protanopia and Deuteranopia o Occurs when someone confuses red and green; they see the world in shades of yellow, blues and greys o Normal visual acuity – suggests that their problem is not that they’re lacking an number of cones, but that they’re lacking the color photo pigment in the cones o Protanopia § People have red cones that are filled with the photo pigments for green o Deuteranopia § People have green cones that are filled with the photo pigment for red o Protanopia and Deuteranopia § If there is even a slight difference in the way each cones photo pigment absorbs light, that person will be able to tell green from red, even if these colors would look different than the reds or greens than a person with normal color vision would see · Tritanopia o Involves the yellow-blue system o Occurs very rarely in less than one in 10,000 individuals o Faulty gene is not carried on the X chromosome, it is equally prevalent in males and females o Thought to occur because the blue cones (much less frequent in the retina to begin with) are either lacking or defective o People see the world in shade of reds, greens, greys o Eg/ Sky looks bright green, banana would look pink Depth, Distance and Motion · Can create a mental image of a three-dimensional world, based on a combination of top-down and bottom-up processing · New visual input from a two-dimensional retinal surface is processed along with our existing knowledge of the environments objects and surfaces to create a 3D world Monocular and Binocular Cues · Two main classes of cues that we use to perceive depth in the environment o Binocular Cues – depth cues that requires two eyes o Monocular Cues – depth cues that require only one eye Binocular Cues to Depth · Binocular Cues o Convergence – a cue to depth resulting from the way our eyes turn inwards to fixate on a specific point § Eg/ looking at your finger at arms length then bringing the finger closer – eye muscles feel strained; the feedback that we receive from these eye movements gives us information about depth § Only works for objects that are relatively close § Eyes don’t have to turn in at all to fixate on the same point for objects that are far away; path of sight for two eyes becomes parallel o Binocular Disparity – a cue to depth resulting from the fact that our eyes will each see a slightly different visual scene § Our visual systems are equipped with a class of neurons that fire maximally only when each retinal image is slightly different · Monocular Cues o Accommodation – involves changes in the shape of the lens as you focus on objects at different distances § Information about an objects distance is coming from the feedback that we get from our eye muscles § The lens can only change so much in shape – accommodation is only an effective cue for depth up to about 2 meters o Motion § Motion Parallax – refers to the fact that when we pass by a scene, objects in the scene pass by us at different speeds, depending on how far away these objects are relative to us · Objects that are close to us appear to sped by much faster than objects that are farther away · Can use the speed of the objects going by us in the scene as we move as a cue to how far away these objects are § Optic Flow – refers to the changing optical projection of a scene that is caused by the motion of the observer, as well as the motion of objects within the scene · As you get closer – an object will get bigger · Entire visual scene changes depending on how close/ far you are · Objects that are close seem to move more in the visual scene than objects farther away · Changes in size and motion can give cues to depth § Pictorial Cues · Interposition o When you have an object that partially blocks another, it is perceived as being in front of the other object o Most effective when objects are familiar and you know what their shapes should be · Linear Perspective o Eg/ if you look down a railroad track; you know the lines are parallel but they appear to converge at a single point o the horizon – provides a clue to depth because objects that are farther away decrease in size and spacing between objects · Aerial Perspective o Texture (aerial perspective) § Objects that are farther away from us will have fewer details § Eg/ can see the texture of gravel that is close by but when it’s farther away it becomes a uniform shade of grey o Haze (aerial perspective) § Objects that are farther away from us will have fewer details § When we’re looking at objects that are farther away, it will be harder to see the outline and texture of the object compared to objects that are closer to you o Shading § Does not give information about how far away the objects is from us § Tells us what part of the object is close to us and which part is farther away § Eg/ Bumps and cave example · So used to light coming from above, automatically use the pattern of light striking an object to tell us whether the object surface is coming toward us or receding away · IF light is striking the top – object is coming toward us · If light is striking the bottom – object is receding Evolution of Depth Perception · The Effect Of Eye Placement o The type of cues that an animal can use to perceive depth depends a lot on where the animals eyes are placed on its head o Prey animals – typically have eyes on side of head § Limited depth perception from binocular cues § Must rely on monocular cues o Predator animals – typically have both eyes facing front § Able to use both binocular and monocular cues Vision and Eye Development · Depth Perception – innate vs learned o Innate § 2 month olds fearful of deep side § Infants as young as 2 months, far too young to crawl, show an increase in heart rate when they’re placed on the deep side but not when they’re placed on the shallow side § Suggests an innate fear of the deep side § Newborn animals that can walk show a reluctance to walk to the deep side of the visual cliff § Suggest that experience with moving around in environment is not necessary to learn basic depth perception o Learned § Infants less than 2 months react differently to deep and shallow side § Infants younger than 2 months show a decrease in heart rate on the deep side and no change in heart rate on the shallow side Specialized visual Systems · Human eyes are simple, insects have complex eye structure (so they have a lot of them) · Slit pupils enhance visual acuity · Predators have large eyes Introduction to Motion Perception · Signals that leave the eye and project to the LGN are carried by two main classes of ganglion cells: the parvo- and magno- streams o Parvo- cells – highly involved in detecting color, pattern and form o Magno- cells – crucial for detecting changes in brightness as well as motion and depth § Found throughout the retina § Cells found in periphery are most sensitive to movement · Motion Agnosia o One patient, LM, suffered brain damage in area V5 of the extrastriate cortex and lost ability to detect movement – things appeared to be frozen and jump from one place to another Normal vision for everything else; could read, recognize Chapter 5: PSYCHOLOGICAL DISORDERS II (Harleen Kaur) Section 5: Schizophrenia (=split mind) · It is idiosyncratic in nature, meaning that the disorder generally presents with a somewhat different set of symptoms from person to person. · Each person who is schizophrenic is unique from others who have the same diagnosis to some extent. · Core symptom – cognitive disturbances · Split mental processes like attention, perception, emotion, motivation and thought; not split personality. · Mental processes appear to be operating independently of one another leading to bizarre and disorganized thoughts and behavior. · Thus, schizophrenia is characterized as a single personality that is shattered rather than distinct multiple personalities. Prevalence and Emergence of Schizophrenia · Prevalence rates range from 0.2% to 2% · Lifetime prevalence about 1% · Rates 11% on average in homeless population · Rare cases of schizophrenia beginning in childhood o Rate is 1 in 10 000 · Schizophrenia emerges in late adolescence or early adulthood · Appears 4 years earlier and more severe in males than females · Men to women ratio 4:1 · Children who later develop full-blown schizophrenia often demonstrate deficits in various of normal functioning o Cognitive functioning – perform below their healthy peers in intelligence tests and tend to have lower grades o Socializing – less responsive, show more negative facial expressions o Motor function – walk at later age · Prodomal phase o The onset of behavioral dysfunction and subclinical symptoms escalate over time Clinical Symptoms of Schizophrenia – Positive and Negative symptoms Positive Symptoms – · Include behavioral excesses or peculiarities, such as o Hallucinations § Sensory perceptions that occur in absence of a real, external stimulus, or gross distortions of perceptual input § Can exist in most sensory modalities: Visual, Tactile, Olfactory § Most common – Auditory hallucinations · Hearing voices of people who are either absent or do not exist · Include insults directed at individual in the form of running commentary on their behavior o “You’re a fool” · Could convey demands o “You must hide from the eagle” o “You must not trust him” · Could be argumentative o “You don’t need to leave the house” § Auditory hallucinations are rooted in the person’s inability to recognize intrusive thoughts as being self-generated and mistakenly identify the source outside of them. § Both speech generation and perception areas are activated during auditory verbal hallucinations o Delusions § A false belief that is irrational or maintained despite being unsupported by external evidence § Considered psychotic symptoms · They mark a serious distortion of reality § Often about thinking or thoughts, including: · Thought broadcast – the individual thinks everyone can hear their thoughts · Thought withdrawal – individual is convinced that thoughts are being removed from his head · Thought insertion – individuals are certain that the thoughts are being placed in their heads
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