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NYU / Psychology / PSY 101 / What makes our senses work?

What makes our senses work?

What makes our senses work?


Psych week 3  

What makes our senses work?


Sensation and perception reading  

● Sensation and perception are the most important to psychology  ○ Sight, hearing, taste etc. → all help us take in the world around  us  

○ Converts real­world info into electrical stimuli that gets interpreted by the  brain 

● The way we interpret the information is our perception on the world  So what’s the difference between the two?

● The physical process  that our senses undergo to respond to the natural outside world is sensation 

○ Feeling the wind on your face 

○ Hearing a horn honking 

○ Tasting the sourness from a lemon

■ This engagement is called transduction 

● The psychological process → making sense of the world around us, is  perception  

○ Smelling cookies and that reminds you of someone making cookies for  you 

○ Hearing a song and that reminding you of a memory 

What is a gray matter?

What makes our senses work? 

● The ability to detect needs a minimal amount of stimulation 

○ This is called the absolute threshold 

■ Differential threshold→ the smallest difference needed to  differentiate between two different stimuli  

● Just noticeable difference 

○ Weber’s Law → idea that a bigger stimuli needs

a bigger difference in order to be noticed

● In order to measure absolute threshold we use signal detection ○ Presents a stimuli at varying intensities to see which level the participant  can reliably detect a stimuli 

○ Correctly indicating a stimuli is called a hit failing to do so is called a miss.  ○ Indicating a sound was heard when it wasn’t is called a false alarm but  indicating a sound wasn’t heard when there wasn’t a sound is correct  rejection 

● Humans perceive things in different ways 

How does the brain relate to the mind?

If you want to learn more check out Intentional manipulation of financial statements to create a facade of a company's financial health.
Don't forget about the age old question of Why do we need research designs?

○ Bottom up processing → little things are used to make the big  picture

○ Top down processing → look at the big picture then the little  things  

● Sensory adaptation→ decrease in sensitivity to a particular stimuli after constant stimulation.


● Vision is actually light bouncing off an object into our eye

○ Light enters through the pupil  Don't forget about the age old question of Who was Eugène Viollet-Le-Duc and what role did he play in promoting the Gothic Revival?

■ Pupil regulates the amount of light that goes into the eye by 

contracting in a lot of light and dilating (getting bigger) in dim light 

○ Light passes through the lens which focuses an image on the  retina→ a thin layer of cells at the back of the eye  

○ From the retina light gets converted into electrical signals by 


■ Rods → black and white used for peripheral vision used  more at night  

■ cones → colored in blue, red and green used in the day  ● Highest concentration in the fovea → central region  

of focus  

○ It passes through the thalamus and then goes to the primary visual cortex  ○ Damage can to areas can cause agnosia→ losses the ability to  receive visual stimuli  

○ Don't forget about the age old question of There are two types of cells?

● The image goes to both eyes through this process 

○ However through this we end up having binocular disparity →  which gives us a slightly different angle which provides us with  perception of 3D space → binocular vision  

The Brain  

● Responsible for all behaviors, thoughts and experiences 

○ Must be implemented through the brain 

● Human cognition is limited 

○ If one behavior uses up most of the resource there is not enough resource left for another behavior 

● The brain uses oxygen and glucose found in the blood in order to function as well as 20% of the calories we consume If you want to learn more check out What are the eukaryotic cells ?

● Has 100 billion neurons 

● When one neuron fires, it suppresses the firing of other nearby neurons. How is the brain divided  

● The brain is divided into three parts  

○ The brain stem, cerebellum, cerebral hemispheres, 

■ Brain stem is the trunk of the brain → regulates breathing,

heart rate and digestion 

■ Cerebellum “small brain” → critical for movement and  


■ Cerebral hemispheres → responsible for our cognitive  

abilities and conscious experience. 

● Holds the cerebral cortex and accompanying white matter    

● Has the subcortical structures being the basal ganglia,  

amygdala, and hippocampal formation. 

■ Cerebral cortex is the largest part of the brain and most visible  

● Has two spheres 

● The folds and grooves of the cortex are called gyri and sulci 

● The two hemispheres are divided into 4 lobes  

○ occipital, temporal, parietal, and frontal lobe 

○ Occipital responsible for vision 

○ Temporal lobe involved in auditory processing, memory, and multisensory  integration 

○ Parietal lobe has the somatosensory → body sensation cortex and structures for visual attention.  

○ Frontal lobe has the motor cortex and and structures for motor planning,  language, judgment, and decision­making.  If you want to learn more check out Which market structure has no competition between firm?

● The basal ganglia are critical to voluntary movement and as such make contact  with the cortex, the thalamus, and the brain stem. 

● The amygdala and hippocampal formation are part of the limbic system ○ The amygdala and hippocampal formation are part of the limbic system So what’s the difference?  

● Both hemispheres are responsible for sensory and motor function. They are  connected by white matter called the corpus callosum  

○ However they function with contralateral representation.  

■ If you need to move your right hand its the left side of your brain  that is sending the command 

○ Other functions are lateralized and stay in one hemisphere for example  most right handed people have language controlled on the left side of the  brain  

○ People do exist who do not have the two hemispheres connected at all  and they are called split brain patients   

Gray vs white matter  

● The gray matter is composed of the neuronal cell bodies  

○ the cell bodies → soma contain the genes of the cell and are  responsible for metabolism which keep the cell alive and  

synthesizing proteins.

● The white matter is composed of the axons of the neurons, and, in particular,  axons that are covered with a sheath of myelin  the fatty tissue that surround  → the cell  

○ Axons are vital for cell communication because they conduct the electrical  signals

Studying the human brain  

● Converging evidence→ strongest type of evidence → similar findings  reported from multiple studies that used different studies  

● Phrenology → one of the first organized attempts to study the brain in  the 19th century  

● Neuroanatomy → dissection of the brain in humans or animals  ○ Used since 340 BC by Aristotle  

● Changing the brain  

○ Researchers use lesions ( cuts in the brain ) to remove parts of the brain  in animals to observe how it affects the animal  

● Neuroimagery  

○ Positron emission tomography (PET) → records the blood flow of  the brain  detects the radioactive substance that is injected into the  bloodstream of the participant just before or while he or she is performing  some task  

○ Functional magnetic resonance imaging (fMRI) → relies on the  blood flow of the brain ,measures the changes in oxygen levels in the  blood and does not require any substance to be injected into the  


○ EEG → measures the electrical activity of the brain 

○ DOI → shines infrared light into the brain, and measures the light  that comes back out. Relies on the fact that the properties of the  light change when it passes through oxygenated blood, or when  it encounters active neurons. 

Wednesday Class lecture 9/19/18  

The brain → national geographic the brain  

● Martha Farah budding scientist that studied the brain  

● Brain science → “Big science” 

● Part of the nervous system that coordinates the body's functions What are we looking at today? Materialism: Brain makes mind 

● Largest section is the cerebrum ¾ of the brain  

○ Controls learning, reasoning and speech  

● Second largest part is the cerebellum  

○ Carries signals to the brain and spinal cord  

● Brain stem ­ controls respiration, digestion, sleep 

○ Pons  

○ Midbrain  

○ Medulla oblongata  

● Diencephalon  

○ Thalamus  

○ Hypothalamus, pituitary gland 

How does the brain relate to the mind 

● Rene Descartes → “I think therefore I am” 

○ Mental events and psychical events have no relationship→  Dualism  

○ We don’t believe that anymore  

● Materialism  

○ What we actually believe in  

○ Mind and brain have a casual relationship  

○ Mental event ( good smell) → physical event ( neurons fire that  something smells good) → mental event ( sight of cookies) →  psychical event ( neurons fire and associate the good smell with  coming off of the cookies)  

■ Medicine effects  

● Placebo vs. real medicine  

○ SSRI (physical event) → I feel better ( mental  

event) → medicine helps  

● The mind is what the brain does! 

○ Brains make minds 

Questions involving materialism  

● Don’t I have free will? 

○ Yes, you choose what you want to mentally experience. 

● How does the outside affect the inside 

● Can “I “ be tinkered with  

○ Yes with certain medications but not all the time  

○ Yes with meditation you can change neural pathways. 

Debates about the brain  

● Trepanation 3500 BCE 

○ First tool used to study the brain  

○ Hole inside of the skull to see what the brain was doing 

● Brain center of mentation?  

○ It was debated with the heart  

○ After much debate the brain won the argument  

● Tissue vs. Ventricles  

○ Idea that the brain was floating around in the brain with a liquid that came  from ventricles 

○ It wasn’t until late 17th century that people acknowledged tissues  ● What makes a cell an cell?  

○ Camillo Golgi → isolated neurons to see the actual neuron and  see the cell body  

● Does the brain function locally or globally  

○ Locally  

○ Sponge vs. bicycle  

■ Sponge takes up water even if you cut part of it off  

■ Bicycle each part has a separate function but if you cut off certain  parts like a wheel you can’t use it, if you cut off a wheel you can still somewhat use it  

■ The brain is like a bike depending on where you cut it is how much  the brain will still work 

● Why is localized function so important  

○ Multiple regions imply multiple cognitive processes  

○ Overlapping brain regions implies overlapping cognitive processes  ● Take home message: Brian function is localized 

Methods of localization  

● Accident  

● Manipulation  

● Non­invasive measurement  

● Franz Gall → Phrenology  

○ Made the assumption that every part of your brain is responsible for your  personality  

○ Thought the brain was like a muscle and if you worked the muscle it would grow and cause bumps in your skull  

○ He would look for the bumps to see what bumps led to certain traits  ○ Wrong→ bumps and traits  

○ Right→ Localization  

● Phineas Gage → Accident  

○ Man who was working got a rod that went through his brain and through  his skull, he walked himself to the doctor and when they removed it he  survived but his personality was forever changed. 

○ Learned that the frontal lobe or frontal cortex was in charge of personality  ● Brain Surgery  

○ Lobotomy used as a tool to punish once again showing the frontal cortex  and lobe are essential for personality  

● Nonhuman subjects→ manipulation  

● Electrical stimulation → Manipulation 

○ Wilder Penfield → Surgical mapping  

■ Would stimulate certain parts of the brain and ask how they felt  ● Stimulating parts of the hippocampus and the patient 

remembering the smell of burnt toast  

● Electrical situation helped map the brain specifically  

the somatosensory cortex → majority in the parietal  

lobe some in the frontal lobe → controls sensitivity of 


● Measurement  

○ EEG → electrodes are placed on the brain to help map what  structure of functioning  

○ fMRI → used mostly for psychology #1 method → relies on blood  and oxygen levels getting to the brain  

○ PET → used mostly for psychology → more invasive  

● The brain has plasticity  

Brain organization  

●  Dimensions of brain organization 

○ Luxuries (things that are uniquely human) are at the top level and  necessities (essential for survival) are at the bottom level 

■ The Levels from bottom to top 

● Necessities → basic life functions → breathing, heart  

rate, pain etc.  

● Basic mostor programs 

● Sensory information 

● Emotion, motivation, simple judgement 

● Voluntary action, complex judgement, symbolic thought 

○ All of this takes place in cerebral cortex in which there are 4 different lobes ■ Occipital lobe→ processes vision  

■ Parietal lobe → attention, orienting objects in space,  


■ Temporal lobe → behind your ears → responsible for  

hearing (olfaction), language, object recognition  

■ Frontal → reasoning,language, executive control  

○ Bilateral symmetry → the left side of the brain is responsible for  motor movement s in the right side and vice versa  

○ Left → Linguistic analysis (grammar)  

○ Right → Paralinguistic analysis (tone)  

Key ideas

● Mind and brain are two descriptions of the same thing 

● Brain function is localized and lateralized, but not simply or strictly  ● The brain is organized hierarchy 

● Brain systems can operate independently and be at odds with each other.  Recitation  


Scientific method is split into two 

● Observation (measurement) 

○ Measurement 

■ Starts with a concept of what your trying to measure 

■ Operational Definition: something that can help you measure and  define the concept 

○ Samples 

○ Examples 

● Explanation

○ Correlation 

○ Causation  


● Asking the right questions to get accuracy 

● Construct Validity: the tendency for a clear relationship between the abstract  concept and the operational definition. 

● Convergent Validity: The tendency for operational definitions to be related to  other operational definitions

○ Positive feelings= life satisfaction

● Predictive Validity: Tendency for measurement to predict a future behavior.  ○ Data that infers a future result 

○ Ex: the SAT or ACT predicted how we would do in college 


● Getting the right/ consistent results from whatever you used to measure  ● Reliability: how likely an instrument or measure will give the same result every  time you use it. 

○ Constant results 

●  Discriminant reliability: how likely an instrument of measure will give different  results for different things. 

A good definition has an construct validity and convergent validity  A good measure has reliability and discriminant reliability 

Population vs. Sample 

● Population: entire group 

○ Every 5 year old 

● Sample: part of entire group ; the subset

○ 5 year olds in NYC 

Both mean and variability must be accounted for in psychological research. Observer Bias vs.Subject Bias 

Correlation does not equal Causation. 

Could be an issue of directionality or a third factor 

Statistical Analysis 

● When we examine a data set, we look for trends and patterns  ● Questons to ask 

○ What causes these patterns 

○ How reliably can we abstract the patterns from our data to the real world  ● Experimenter expectations → observation bias  

● Nature of participants 

● Sampling methods 

● Random error 


We can account for randomness by applying a probability model  ● P­value: how likely is it that we see the same results f random echance is the  only factor 

○ Always want a super low P­value 

● P­hackin­ when someone uses the wrong stattistical test to get a lower P­value 

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