Introduction

Question 1

What is the goal of perception

Answer 1

To inform us about the properties of the environment that are important for our survival

We will not be here if peripheral system did not work

Question 2

How is the goal of perception achieved?

Answer 2

Using information from our senses our perceptual system creates a model of the environment in our minds

Question 3

Diagram of senses part of perception

Answer 3

Question 4

“Create model of our environment”

Important note on model:

Answer 4

To appreciate what “sensations” and “perceptions” actually are, it is crucial to appreciate that this reconstructed representation or internal “model” of our environment is not simply a replica of our surrounding physical environment.​

Let me try and convince you that your perceptions are not simply a copy of the external world…

e.g DOES NOT WORK BY TAKING PHONE AND TAKING PICTURE AND immediately goes in our mind

It is an ACTIVE PROCESS

Question 5

Aims of perception

Answer 5

1. Some objects or stimuli that you see (i.e perceive in isolation may appear differently in the presence of other stimuli)
2. We sometimes see “things” that are not there
3. And sometimes we can even fail to see “things” that are in fact out there…

Question 6

Aim of perception one explained

Answer 6

e.g if you change position relevant to other stimuli appearance will change

What we perceive also depends on what else is out there:- contextual effects modify the appearance of objects (e.g. perceived brightness of an object or perceived orientation of lines).

Question 7

Aim of perception two explained

Answer 7

• Such cases indicate that the process of building an internal model of our environment, namely of forming Perceptions, does rely on some stored knowledge of the physical properties of objects in our environment…​​
• For instance, if I cannot see circular sections of the underlying objects then there must be an opaque (white, in this case) circle above them…
• We may perceive “things” that are not there…(e.g. illusory dots, illusory motion or size constancy effects)​

Question 8

Aim of perception three explained

Answer 8

And sometimes we fail to see “things” which are in fact there…(e.g. change blindness).

Question 9

Conclusion of perception

Answer 9

Perception is not a simple replication of our physical environment.

Question 10

Diagram of perceptual knowledge

Answer 10

Figure 1.1 The perceptual process. These seven steps, plus “knowledge” inside the person’s brain, summarize the major events that occur between the time a person looks at the stimulus in the environment (the tree in this example) and perceives the tree, ​

recognizes it, and takes action toward it.

Question 11

Explain this perceptual process in the diagram below:

Answer 11

1. Stimulus in environment e.g tree
2. Light is reflected on object and eye will focus on forming an image at the back of the eye
3. Sensory organ of eye - receptor processes
4. Neural processes towards visual pathway
5. Perceptions are sometimes affected by stored knowledge
6. What we perceive is function of past experience

Question 12

Explain this

Answer 12

• Figure 1.6 Steps 5–7 of the perceptual process. The behavioral responses: perception, recognition, and action.

Question 13

Where does perception occur?

Answer 13

In the brain

Question 14

What are brains made out of?

Answer 14

(many) neurons that communicate with each other using electrical signals - more on that process in the next lectures.

Question 15

Why is it a problem that electrical signals is the only language that the brain understands?

Answer 15

• Language that neurons communicate each other with
• It is a “problem” because the stimuli that arrive at our different senses are not electrical signals:

Question 16

Example of why is it a problem that brain only communicate with electrical signals?

e.g

organs respond to different stimuli at senses are not electrical signals

Answer 16

• Eye – Light (electromagnetic radiation)​
• Ear – Sound (air pressure)​
• Vestibular system – Head movements (mechanical energy)​
• Tongue – Taste (chemical / molecular shape)​
• Nose – Odour (chemical / molecular shape)​
• Skin – Touch, Temperature & Pain (Mechanical, thermal & chemical energies)

Question 17

What is the solution that our brain can only process electrical signals?

Answer 17

Transduction

Question 18

What is definition of transduction?

Answer 18

the process by which individual sense organs convert (or transduce) energy from any environmental events into neural activity.

Transduction is a conversion

Question 19

How does transduction covert energy from enviro into neural activity?

Answer 19

Each of our sense organs (eyes, ear, nose tongue etc.) contain specialised receptors that translate the energy from corresponding stimuli into neural activity which our brain can then process.

e.g each sense organ have a different repecetor cell that is specialised

so take energy and make an electrical signal to the brain

Question 20

Example of transduction in perceptual process

Answer 20

• E.G
• IN this case visual system the light will stimulate photoreceptor and output is electrical signals that could be processed into perceptual system

Question 21

What are the two methods that get the electrical signals (just converted from transduction) into the brain?

Answer 21

1. Transmission
2. Processing

Question 22

What is transmission?

Answer 22

carries the signals from the receptors to the brain and around the brain.​

Also around the brain region to another to make a decision

Question 23

What is processing?

Question 24

Example of transmission, transduction and processing

Light

Answer 24

Figure 1.3 (a) Transduction occurs when the receptors create electrical energy in response to the light. (b) Tranmission occurs as one neuron activates the next one. (c) This electrical energy is processed through networks of neurons.

• Processing is unique as it makes our perceptual systems what they are

Question 25

Example of transmission

Answer 25

• Comparison of signal transmission by cell-phone and the nervous system. (a) Cell phone #1 sends an electrical signal that stands for “hello.” The signal that reaches cell phone #2 is the same as the signal sent from cell phone #1.

Question 26

Example of processing

Answer 26

The nervous system sends electrical signals that stand for the moth. The nervous system processes these electrical signals, so the signal responsible for perceiving the moth is different than the original signal sent from the eye. ​

Question 27

Diagram of knowledge top down processing

Answer 27

Question 28

Two interacting processes in perception

Answer 28

1. Bottom -up processing
2. Top down processing

Question 29

What is bottom up processing?

Answer 29

Processing based on incoming stimuli from the environment​

Also called data-based processing

This is where flow of information from the environment through the sensory system towards the brain

Question 30

What is top down processing?

Answer 30

Processing based on the perceiver’s previous knowledge (cognitive factors)​

Also called knowledge-based processing

Means from the brain down towards lower areas of the brain

based on stored knowledge

Question 31

Example of bottom down processing and top down processing working together

explain

Answer 31

Incoming data from the outside towatds the brain towards sensory organ

incoming data : bottom up

recognising moth: top down

In this example, (a) the image of the moth on Ellen’s retina initiates bottom-up processing; and (b) her prior knowledge of moths contributes to top-down processing.

Question 32

Another example of top down processing

Answer 32

Question 33

Three approaches to study of perception

Answer 33

1. Psychophysical approach (PP)
2. Physiological approach (PH1)
3. Physiological approach (PH2)

Question 34

Three approaches to study of perception

Are they related?

Answer 34

These stages are interrelated and inform one another; we will consider several examples from each approach throughout this course.

Question 35

What is Psychophysical approach? (PP)

Answer 35

the stimulus-perception relationship​
​You study the relationship between your perceptions as a function of changing physical properties

e,g changing length,colour, temperature of objects

Question 36

What is Physiological approach (PH1) ?

Answer 36

the stimulus-physiology relationship​

e.g Recording the activity of a visual neurons you go and record the electricity as a function of systematically manipulating stimuli in outside world gives insight how neurons process info

Question 37

What is Physiological approach (PH2)?

Answer 37

the physiology and perception relationship​

using EEGs or fMRI

Question 38

Examples of approaches to study perception

explain

Answer 38

(a) The psychophysical relationship (PP) between stimulus and perception: Two colored patches are judged to be different. (b) The physiological relationship (PH1) between the stimulus and the physiological response: A light generates a neural response in the cat’s cortex. (c) The physiological relationship (PH2) between the physiological response and perception. A person’s brain activity is monitored as a person indicates what he is seeing.

Question 39

Example of psychophysical experiment

Answer 39

(a) A reaction time experiment in which the subject was told to look at the + sign, but pay attention to the location at A, and to push a button as quickly as possible when a dark target flashes anywhere on the display. ​
​
(b) Reaction times in milliseconds, which indicates that reaction time was faster when the target was flashed at A, where the subject was attending, than when it was flashed at B, where the subject was not attending. (Data from Egly et al., 1994)

Question 40

Human factor psychology task

Answer 40

Task: use your data from your Simple Reaction Time experiment to aid the design and implementation of a Collison waring system for a car.​
​

You will have access to data from the car radar that constantly measures and monitors the distance to the car in front of you.​
​

Your task is to advise the engineering team at what measured distance they must flash the ​
“You must break” waring signal to the driver before it is too late to break… ​

70 MPH = 112.654 Km/hour or = 31.3 metres/sec​
or = 0.0313 metres/msec. [1000 milliseconds = 1 sec.]​

Airing on the safe side of your results, we should use the higher average Reaction Time value of 300 msec. ​
​

300 (msec Reaction Time) x 0.0313 (metres covered every msec @70MPH) = 9.39 meters.​

Thus, flashing a warning light at any distance below this value will be too late for the driver to react to…

Question 41

Difference between sensation and perception

Answer 41

The sensation is identified as involving simple elementary processes that occur right at the beginning of a sensory system

e.g when light stimulates the receptors in the eye

Perception is identified with complex processes that involve higher-order mechanism such as interpretation and memory that involve activity in the brain

Question 42

Between steps 1 and 2 is distal and proximal stimuli

Answer 42

Distal stimulus at the distance

distance something out in envnrioment

Person’s perception of the tree is based not on the tree getting into his eye but the light reflected from the tree and reaching the visual receptors.

proximal stimulus is then created image created on the retina

Question 43

Step 3 in more information

Answer 43

• Sensory receptor specialised to respond to environmental energy, with each sensory system’s receptor specialised to respond to specific type of energy

Question 44

Step 4 more detail

neural processing

Answer 44

This is once transduction occurs

represented in electrical signals

Question 45

What is the oblique effect?

Answer 45

People see vertical or horizontal lines better than lines orientated obliquely (any orientation other than vertical or horizontal)