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Unit 2: PERCEPTION

& NEUROPSYCHOLOGY

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SENSATION AND

PERCEPTION

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What is Sensory System? A sensory system is a part of the nervous system

that consists of sensory receptors (neurons), neural pathways, and those parts of the brain responsible for processing the information.

Senses are the channels through which we come to know about the world. The 5 senses are:

Vision -enables Hearing Taste Smell skin

The sensory organ senses energy and convert it to a code, which then transfer it to the brain for further process.

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What is Sensation? Sensation is a process of detecting & encoding energy

stimulus in the environment. Stimulus produces physical energy, light, sound, hot,

cold. In sensation process:

Sensory organ senses energy and convert it to a code transfer it to brain for further process.

The first step in the “sensing the world” is the task of cell receptor.

Thus, The function of any sensory organ is to detect environmental stimuli and start an action potential on its way to the brain.

i.e. we receive stimulus from our environment via our sensory system ( the sense organ).

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What is Perception? Perception is a process whereby, sensory

stimulus in the environment is converted to mental representation (repeat).

The process of perception and sensation cannot be altered/change

Perceptions refers to the way the world looks, sounds, feels taste or smell.

It is what is immediately experienced by a person It is the first step in processing information around us.

How sensory events are translated into patterns of activities in the sensory channels & central nervous system.

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Process in Perceptions Sensory patterns (stimulus received from the

environment) merely provide the raw data for experience.

The sensory information is then transformed, elaborated and combined with memories to create what we actually experience or perceive.

“Part of what we perceive comes through the senses from the object before us, another part… always comes… out of our own head”

(William James)

“out of our own head” refers to elaborations, transformation & combinations of the sensory inputs that make our experience/perceptions of the world what it is.

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Process in Perceptions (Con’t…)

We must understand the meaning of perception in order to understand the relationship between environment & behavior.

Therefore, in order to understand perception, we must understand the following process/phases:detectionrecognitiondiscriminationscaling

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4 phases in the Process of Perceptions

1. Detecting stimulusFeel/aware of changes in our environment, that is

changes from nothing to something (0-changes felt).

Detection is important for living beings.

2. Stimulus RecognitionImportant task in the perception system is to

recognize & identify stimulusNormal/everyday stimulus easy to identifyDifficulty in recognizing due to context,

alternative and perceptual set that a person have.

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4 phases in the Process of Perceptions3.Stimulus Discrimination

Discriminate types of stimulus received. Increment of stimulus intensity will enable a person

to differentiate different type & degree of stimulus.

Thus, an organism/individual must know whether the stimulus in his/her immediate environment is at a comfortable level or need to be change.

4.Stimulus Scaling All living beings are involved in measurement. A person can measure the magnitude of a

response by looking at the magnitude of a stimulus in order to overcome a certain situation.

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NERVOUS SYSTEM

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What is Nervous System? The Nervous System act as the ‘control system’

that "tells" the parts of our bodies what to do and when to do it.

The nervous system is divided into 2 major section:- The Peripheral Nervous System

sensory neurons running from stimulus receptors that inform the central nervous system of the stimuli

motor neurons running from the central nervous system to the muscles and glands - called effectors - that take action.

The Central Nervous System The central nervous system consists of spinal

cord & brain

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Central Nervous System

Consist of Spinal Cord & Brain 2 types of Cell :

Neurons Nerve cell that send and receive information

(information carriers of the nervous system) Brain have 10-12 billions neurons inter-connected to

other neurons Glial Cells

Also known as neuroglia Form the “glue” of the brain they support & protect

the neurons. The ‘housekeeping’ cells of the nervous system

essential for the nutrition of certain neurons, & the removal of dead cells from the nervous system.

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Neurons Neurons or sensory neurons are nerve cells in the

nervous system, and they act as the information carriers of the nervous system. Neurons are responsible for converting external stimuli from the environment into internal electrical impulses.

Neurons are cell bodies with nucleas, composed of DNA, which contains the cell’s genetic programming. All neurons have cell body, dendrites and axon. Dendrites is usually short and have many branches which

receive stimulation from other neurons. Axon, usually quite long. Its function is to conduct nerve

impulses to other neurons or to muscle or glands.

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Cells in the central nervous system increases rapidly between the 25th week of gestation and the first few months after birth.

Neurons are cell bodies with nucleas, composed of DNA (which contains the cell’s genetic programming).

As the brain grows the cell migrate to various parts spread out to perform different functions they sprout axons & dendrites.

Through axons/dendrites send signals to other neurons & receive incoming message through connection called synapses.

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Nervous System

Function of Nervous System:

The control system that "tells" the parts of our bodies what to do and when to do it.

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What is synapses? Synapses is the

nervous system connection link ie the connection between nerve cells.

Connections made through the stimulus sending signals to the brain.

The brains define what is it/who we are?

With proper stimulation, the synapses become stronger.

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Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical signals into chemical ones.

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Neurotransmitters Neurotransmitter is a chemical that transmits

information across the junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a muscle.

Neurotransmitters are stored in the nerve cell's bulbous end (axon).

When an electrical impulse traveling along the nerve reaches the axon, the neurotransmitter is released and travels across the synapse, either prompting or inhibiting continued electrical impulses along the nerve.

There are more than 300 known neurotransmitters. For examples, Acetylcholine (Ach), Dopamin, Endorfin, Norepinephrin, Serotonin, GABA (gamma amino butyric acid)

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BRAIN

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What is brain? Weights only 3 lb. Looks like a gray, unshelled walnut. The most complex structure in the world. Body most vital organ. Each person is born with over 100 billions brain

cells (neurons). Brains can send signals to thousands of other

cells in the body at speed of more than 200 miles per hr.

Brain growth before &after birth is fundamental to future development.

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In the uterus an estimated 250,000 brain cells form every minute.

By birth almost 100 billion nerve cell are formed, but not fully develop.

At birth baby brain weight is about 25% of an adult. By first year 70% and by end of 2nd year 80% It then continues to grow slowly by aged 12

almost the size of an adult. The volume & weight of a brain can be

measured by using:- Before birth ultra sound After birth Measure circumference of baby’s

head. First 3 years of life is critical to baby’s brain

development.

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1 organ with 3 mini brains:

Brainstem (inner coreBreathing, heartbeat

muscle movement, reflex behavior

Limbic systemCovers the brainstemMotivation, emotions,

& long term memoryCerebellum – control

automatic movements & balance

Cerebral cortexHigher mental

process.Learning, memory,

Thinking, Language Last to develop

Structure of the Brain

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Thin layer on the brain’s surface that include lobes or sections:

Occipital lobe Process vision.

Temporal LobeProcess hearing

Parietal LobeProces sensory stimuli

Frontal LobeCritical thinking & problem solving

Cerebral Cortex

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Consciousness and

Information Processing

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Consciousness Awareness Knowledge State of wakefulness Much of human information processing

seems to involve awareness such as perception, imagery and emotion.

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Information Processing Cognitive psychology developed around late

1950’s. Primary focus of cognitive psychology is on memory

(the storage & retrieval of information) A group of information theorist used computer as a

model for the way human think. They look at:

The way people take in, process & act on information focusing on attention, perception & memory.

Information processing model are used to describe and explain cognitive (mental) process, such as thinking & problem solving.

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Human mind is like a computer: Takes information Organizes information Store information for later use Retrieve information when necessary

Types of Memory Sensory register Short term memory Long Term memory

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Types of Memory Sensory register

Part of memory that receives all the information a person senses.

Short term memory Also known as working memory A part where new information is held

temporarily, until it is either lost or placed into long term memory

Long Term memory Part of memory which has unlimited capacity &

can hold information indefinitely.

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When people pay attention to an information the sensory register will pick the information goes into the working memory.

Once in working memory information is processed/ practiced within 5-20 sec then transfer to the long term memory.

If people don’t pay attention the information is lost. New information will be transferred to Long term

memory when : it is linked in some way with prior knowledge already in the

LTM. Information is translated into meaningful form (encoded)

Information in the LTM is retrieve through a process of identification & recall for a particular purpose.

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Strategies in encoding/ memorizing

Chunking Rehearsal Imagery Mnemonics Schema activation Level of processing

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Strategies in encoding/ memorizing Chunking

Breaking the information into manageable chunk.

eg. OFHRTJUDYCX OFH RTJ UDY CX Rehearsal

Simple repetition Elaboration when info to be remembered is

linked to other information Imagery

Conjured image of an object/related meaning.

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Strategies in encoding/ memorizing Mnemonics

Memory strategy to help remember information Eg. A rhyme or pairing of to-be-learned

information with well learned information. Schema activation

Strategy to use with encoding complex info. relates new information to prior knowledge.

Level of processing Material that is only skimmed will not be as

deeply processed as material that is studied in detail.

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Information Processing Model: The Stage Theory (Atkinson & Shiffrin, 1968)

Information is processed & stored in 3 stages:

1 Sensory memory (sensory register)

2 Short term memory

3 Long term memory

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Sensory Memory Memory starts with a sensory input from the environment. Sensory as a source of information (vision, light, sound,

smell, heat, etc) In the sensory register input are held for a very brief

time several seconds. Sensory receptor (neurons) send this message (receive

from sensory organ) as a form of energy to the brain. Through the process of transduction (change from one

form of energy to another), a memory is created. Memory in the sensory register is very short less

than ½ second for vision and about 3 sec for hearing. Sensory memory is a very important stage learner

must attend to the information receive at this initial stage in order to transfer it (info) to the next stage.

Individual are more like to pay attention to a stimulus if: It has an interesting features It activates a known pattern

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Short Term Memory (STM) Also known as the working memory Relates to

what we are thinking about at any given moment in time.

STM is created through:-Attention to an external stimulusAttention to internal thoughtsBoth external stimulus and internal thoughts.

STM will last for 15-20 sec unless is repeated (known as maintenance rehearsal) can last for up to 20 min.

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Short Term Memory (STM) Process of rehearsal:

Attention focused on items of information repeated over & over (silently/loudly) processed in such a way & link it to other prior information that has already been stored in the memory.

Elaborative rehearsal: giving the material organization & meaning as it is being rehearsed use strategies that give meaning & organization to material so that the to-be-remembered information can be fitted in with the existing organized long term memories.

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Long Term Memory (LTM) Information that is not being processed will be lost/ forgotten. When information are placed in LTM, they are put into

organized categories where they reside for days, months, years, life time.

When you remember something a copy of the item is withdrawn (retrieve) from the LTM.

Some theories believe there is no true forgetting from the long-term memory because once information is stored, it is there for good.

If/when we seem to forget it is because we have trouble retrieving or getting access to what has been stored (information stored in unorganized way).

Thus, information in the Long Term Memory must be encoded, stored and placed in memory in organized way for easy retrieval.

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Where does consciousness enter

into human information processing?

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Situation when consciousness enters in human information processing:

We may be conscious of the stimuli that we analyzed.

When we select more detailed attention. When we are conscious of what we learn. When we commit to memory. When we are conscious to the response we make

to such stimuli. When the required responses are complex or new

we may be aware of devoting effort to planning, monitoring & executing the information.

In reflective thoughts or problem solving we may have some awareness of internal processing in the form of thoughts, emotions, images, etc.

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ENVIRONMENTAL PERCEPTION

& ENVIRONMENTAL

COGNITION

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Environmental Perception The initial gathering of

information through our sense organs (sight, sound, touch, taste, smell) that leads to an interpretation of the external stimuli and assignment of meaning

“It’s a tree” (identification)

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Environmental Perception (EP) Environmental Perception is an initial gathering of

information. It includes:-

the ways & means by which we collect information through all our senses.

aspects of how we appraise & assess environment (initial information gathering phase process).

Individual perception of an environment may differ. WHY? This could be due to:

Personal Variation Physical Variations Combinations of personal & physical variations

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Differences in perception Personal Variation

Culture differences Perceptual ability Sex Training/education

Physical Variations Degree of visual complexity

However, no single influence (factor) by itself determines what an observer perceives.

Any given perception is determine by the force of many influences, each delivering its own large or small push towards shaping the overall perception.

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What is COGNITION?

The mental process of knowing, including aspects such as awareness, perception, reasoning, and judgment.

Thus, Cognition involves the mental processes used in perception, memory, communication, thinking

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What is Environmental Cognition? Environmental

Cognition:

Concerns the way we acquire, store, organize and recall information about locations, distances & the arrangements in buildings, streets and the outdoors How we store an image

of that tree, its size, location, the surrounding context, etc in our head

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Environmental cognition includes Spatial Cognition – ie. The thinking process that help us: “wayfind” Estimate distances Recognize route cues Read maps Understand the relative location in space

Spatial cognitions includes the concept of cognitive maps.

What is Cognitive map?: A pictorial and semantic images in our head of

how places are arrange. E.g: evidence of cognitive mapping is in

advertisement, road maps, road sign, in every person’s memory & thinking etc.

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What influences our thinking about our everyday setting?

Many factors & among others are:- Stages of life Spatial ability Familiarity with the place Sex Personal characteristics (personality, intelligence,

emotion, etc)

Environmental Environmental Perception Cognition

Not a distinct concepts but a continuum

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Differences between objectperception and environmental perception

Environmental perception studies more complex stimuli

Perceiver is part of the scene (may have multiple perspectives)

Perceiver is connected to the scene by a clear goal or purpose

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Goal States in Perceiving the Environment

Utilitarian purposes – we want to do something in the environment, e.g., wayfinding, safety, etc.

Aesthetic purposes – enjoyment of the environment’s beauty

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Perception is an active process

We “construct” our perceptions of the world. Our “constructions” of reality are influenced by

our expectations, goals, etc.

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Brunswik’s Lens Model Theory Egor Brunswik Both perceiver (observer) & environment are

important. The environment offers lots of cues — perceiver

needs to make sense out of key ones to function in the environment.

No single cue is perfectly reliable, but each has a certain probability of being an accurate clue to the environment

Prior knowledge is important The development of mental image of a place (eg

home) involved environmental cognitive process linked to our evaluation of the environment.

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Brunswik’s Lens Model •Ecological validity•Relation between information (X) and environment

•(MISLEADING)

ENVIRONMENT

X1

X2

X3

X4

Xn

PERSEPSI

INFORMASI (Cues)

• Utilization• Information

processing

• Functional validity

• Relationship between perception and environment checked through action

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Brunswik differentiate between distal cues (distal stimulus) variables and proximal cues (proximal stimulus) variable: Distal cues

Source of incoming sensory pattern (traffic light is red, lights in the store)

Cues that give a meaning to the observer for him/her to make certain decision.

Proximal cuesThe actual pattern of light on the retina of an

observer’s eye ( car must stop at the traffic light, the shopkeeper is in)

The conclusion that you actually make from the cues that you observe.

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Example: Driving up to an intersection with a

traffic light that has just turned green

Goal: Driving through the intersection

Distal Cues Proximal Cues traffic light is green “safe to go”

people walking on sidewalk “no one about to cross street”

buildings at side of road “ignored”