Week 1 : Introduction Flashcards
Why is this psychology?
- the goal is to understand perceptual experience, how our brains make sense of the sensory world around us
- understanding how our minds, through our brains, interpret the world around us in an inherently psychological goal
- lastly, psychological processes (like attention, intention, emotion & biases) influence the ways in which we perceive the world
Why study perception at all?
- Creating an analog perception of the world through a digital signal
- human perception greatly improves all processes in the social world
Bottom-up & top-down flow of information
Perception represents a combination of bottom-up processes (shape, colour, motion) with top-down information that arises from cognitive processing of a stimuli (predictions, theory, knowledge, context)
The senses…
- vision
- hearing
- smell (olfaction)
- taste (gustation)
- light touch
- pressure
- cold
- heat
- pain
- itch
- vestibular
- proprioception
Sensation…
- refers to the registering of a physical stimulus on our sensory receptors
- sensation changes physical stimuli into information in our nervous system
- about stimuli
Perception…
- refers to the later aspects of the perceptual process which involves turning the sensory input into meaningful conscious experience
- the translation of the neural signal into useable info
- perception occurs after cognitive processing begins, typically in the cerebral cortex
- about interpretation
transduction & neural responses
- for each of our sensory systems, we have specialized neural cells called receptors that transduce (transform) a physical stimulus into an electrochemical signal… called a neural response & sent to the brain
- this is how stimuli the outside world becomes perceptual experiences
- sensation = transduction & perception = guide functional action
Phenomenology…
- our subjective experience of perception
- refers to our internal experience of the world around us
- unique creation of the living brain
history of sensation & perception
- Writings on disorders of sensation and perception go back all the way to the ancient Egyptian
- Aristotle theorized extensively about perception and its causes (motion aftereffect/waterfall illusion & touch between tips of fingers)
- Later in the 19th century, German physiologists began experimenting on the neural processes that underlie sensation, and others started the field of psychophysics
- Later influences in the development of sensation and perception research include gestalt psychology, Gibsonian direct perception, information processing and the computational approach.
- Neuroscience also addresses issues of sensation and perception.
- Neuroscience research includes single-cell recording, neuropsychology and neuroimaging.
Helmholtz…
- the first person to determine the speed of the neural impulse (or action potential)
- developed the concept of the trichromatic theory of colour vision
- developed a general theory of how our senses work & argued that the info from the sensory signal itself is inadequate to explain perception, so the signal needs to be interpreted by active cognitive process… so we must incorporate info from existing knowledge to completely perceive the world
- called unconscious inference
- work influences information processing and computational approach
Hering…
- opponent-process theory
- thought that environmental inputs and our sensory systems are sufficient for us to grasp the structure of the perceived world
- influences gestalt psychology & direct perception theory
Weber…
- Weber’s law states that a just-noticeable difference (JND) between two stimuli is related to the magnitude/strength of a stimuli
- concerned w the perception of difference between 2 stimuli
- it is harder to distinguish between 2 samples when they are larger/stronger levels of stimuli
Fechner…
- founder of psychophysics = the study of the relation between physical stimuli and perception
- fechner colour effect = moving black-and-white figures create an illusion of colour
- fechner’s law = states that sensation is a logarithmic function of physical intensity… our perception of the intensity of a stimulus increases at a lower rate than does the actual intensity of the stimulus
psychophysical approach
- seeks to understand how the physical properties of a stimulus affect its perception
- This is often done by measuring by how much a particular stimulus property must be changed in order for that change to be noticeable (Weber)
- absolute threshold, JND
direct perception (Gibsonian approach)
- the world generates so much information that the senses only need to pick it up directly
- emphasizes ecological realism in experiments
Information-processing approach
- approach says perceptual & cognitive systems can be viewed as the flow of info from one process to another
- information is collected by sensory processes & then it flows to a variety of modules that decode info, interpret it & allow the organism to act on it
- each of the stages takes a finite amount of time, and therefore these processes can be observed or measured by recording reaction times
Computational approach
- studies perception by trying to specify the necessary computations the brain would need to carry out to perceive the world
- heavily influenced by growth of comp sci and AI
- sought a mathematical explanation for perceptual processes (esp vision)
- often more theoretical, focusing on modelling perception
Microelectrode
- one of the most important developments in neuroscience
- device so small that it can penetrate a single neuron in the mammalian central nervous system without destroying the cell & record activity
- this method allows the recording of behaviour of a single neuron & can be used to determine what stimuli it responds to
- Hubel & Wiesel
neuropsychology…
the study of the relation of brain damage to changes in behaviour
Agnosia…
- deficit in some aspect of perception as a result of brain damage
cognitive penetration**
- the view that cognitive and emotional factors influence the phenomenology of perception
- means that nonperceptual factors affect what we see, hear, feel and taste
- cognitive impenetrability is the opposite and says perception is not affected by cognitive factors - this is the dominant view saying that perception remains the same regardless of cognitive/emotion state & what changes instead is our attention, expectation/mood state
psychophysical scale
- a psychophysical scale is one in which ppl rate their psychological experiences as a function of the level of a physical stimuli
- involve presenting a controlled stimulus to participant & asking them questions that allows the answer to be quantified
- focus on the relation between physical properties & perception
- detection test, comparison test, a magnitude test or a preference scale
Method of limits
- stimuli are presented on a graduated scale & participants must judge the stimuli along a certain property that goes up/down
- researcher hopes to pick an extreme value that’s readily detected & a level that is never detected & then several levels between them
- used to determine both absolute & different thresholds
Absolute threshold
- the smallest amount of a stimulus necessary to allow an observer to detect its presence
- To determine an absolute threshold with the method of limits, researcher use an ascending series and a descending series
- ascending series = stimulus gets increasingly larger
- descending series = stimulus gets increasingly smaller