Textbook Notes (362,734)
Canada (158,032)
Psychology (4,729)

Sensation and perception.docx

10 Pages
Unlock Document

Western University
Psychology 2115A/B
Anthony Skelton

Sensation and perception – Lecture 1 When comparing colours, our visual system compares two different colours and this can change our perception when looking at these colours Perception is the conscious view of a stimulus, a conscious sensory experience. Perception is used in relation to other sub-fields of psychology such as neuroscience, developmental psychology and cognitive psychology. It also applies to health and medical applications, the philosophical need to know and enhanced awareness of ourselves. Perceptual process - Environmental stimulus o We take this outside stimulus, this starts our own perception - Principle of transformation (done by light reflecting on the retina) - Receptor processes (transduction) o These receptors are specific for each change, and these transform these stimuli into electrical signals - Neural processing o Brain is processes these electrical signals and turns into a behavioural responses - Behavioural responses Types of processing - Bottom – up processing o Emphasizes the basic components of an object o Paying attention to specific letters, when reading a paragraph with mistakes - Top – down processing o Emphasizes high-level expectations o When seeing the picture of a dog, made by the white background with black spots we are able to see this dog descriptor and relate it to the picture o Able to read through the mistakes when presented, we tend to relate words on the whole shape of the words Psychophysics - Measures the relationship between the magnitude of a sensation and the magnitude of the stimulus that gave rise to that perceptual sensation - People are more likely to respond to from a straight (vertical or horizontal lines) because we have a better vision in this case - Peoples reaction is much quicker when dealing with these lines, this is why we can easily tell when a picture on the wall is not straight The physiological Approach - Measures two relationships o Relationship between stimuli and physiological response o The relationship between physiological responses and behavioural responses Measuring perception - How much stimulation is needed to know it is present? The minimal amount of energy for an observer to detect the stimulus is known as the absolute threshold Psychometric function - Relationship between the psychological sensation (what you perceive) and the actual physical perception of the stimulus Gustav Fechner - Possible to measure sensation and perception - And what is going on in terms of a person’s experiments - Invented vector scale based on 7 insights Method of limits - Procedure to measure absolute threshold in which the experiments presents stimuli in ascending order or descending order - you can either start with something way above or way below the absolute threshold and connect it closer to the absolute stimulus - average of the separate crossovers relates to the threshold - threshold is variable due to knowledge and experiments Method of adjustment - a procedure to measure absolute threshold in which the intensity is adjusted continuously until the observer can just barely detect the stimulus - can get to the threshold quickly, but studying in the close range around the threshold - staircase method o reversals Method of constant stimuli - a procedure to measure the absolute threshold in which a fixed set of stimuli are selected in advance, and presented in random order Difference threshold (DL) - Ernst weber - How much change in a stimulus is necessary to know that there is a change in that stimulus? - Minimum difference between two stimuli which is necessary for us to know that there is a difference in two different stimuli, this threshold is used for us to realize two different stimuli are for so different, the point where there is a 50/50 chance of them saying yes and no. - Smallest amount where the individual can discriminate the difference in stimulus, you just need a small change in intensity to realize that it is different - For weight there is a discrimination of 2%, this is the point where we can tell the difference Weber’s law - Is the difference threshold constant across all possible stimulus intensities? o No the difference threshold changes as a function of the magnitude of the standard stimulus o For example if we are holding 10 pennies in one hand you would be able to find the difference if you add one more penny to the other hand because it is over the two percent , if we have 200 pennies that one penny will not make a difference because it is less than two percent - Smaller weber fraction, is a larger sensitivity where a larger weber fraction is a smaller sensitivity Magnitude estimation (scaling) - SS Stevens - Procedure to measure the relationship between perceived magnitude and stimulus intensity - Gives observer a standard stimulus and a value for the intensity, this is standard stimulus is compared to another set of stimuli, and you are supposed to assign numbers to the intensity of the stimuli Compression and expansion - Response compression o As intensity increases, the perceived magnitude increases more slowly than the intensity o An underestimate of the exact amount - Response expansion o As intensity increases, the perceived magnitude increases more quickly than the intensity o Example – electric shock, a doubling of electric shock, it will feel like more than double Beginnings of perception – chapter 2 part 1 Light and the Eye Light - Electromagnetic spectrum o Continuum of electromagnetic energy that incorporate these wavelengths and colour coordinates o We can see from about 400-700 nm o Short wavelengths that we see are known as purple and blue o Longer wavelengths that we see are known as yellow and red o the way we perceive these wavelength gives us this coloured vision - Visible light o The light that we can see as human beings, we can only see a small portion of the spectrum - Photons o Packets of energy, and the smallest amount of light energy is known as a photon Structure of the eye - Cornea o Transparent, and doesn’t contain blood vessels to block the light to reach the cornea o A lot of nerve endings, which is used as a protective factor o Fixed lens that gathers information for the rest of the eye o Shape of the eye, allows us to see just behind us, which adds to the perceptive field o Projects the
More Less

Related notes for Psychology 2115A/B

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.