Sensation and Perception SAC Revision Flashcards
Dependent variable (DV)
The aspect of a participant’s behaviour or experience that is assumed and expected to change as a result if the manipulation of the IV selected by the researcher.
Independent variable (IV)
Referred to as the ‘treatment’ variable to which participants may be exposed (or not exposed).
Population
Refers to the entire group of research interest from which a sample is drawn and to which the researcher will seek to generalise (apply) the results of their investigation.
Sample
A sample is a subset or part of the population that is selected for research purposes.
What are the three sampling procedures?
-Convenience Sampling
-Random Sampling
-Stratified Sampling
Convenience Sampling
Occurs when the researcher cannot obtain a complete list of the population, or divide it into subgroups, and therefore the sample becomes whoever is most accessible.
Random Sampling
Is a sampling technique that ensures every member of the population of research interest has an equal chance of being selected to be part of the sample.
Stratified Sampling
Is the process of selecting a sample from a population composed of various subgroups in such a way that each subgroup is represented.
What are the three experimental designs?
-Between Subjects Design
-Within Subjects Design
-Mixed design
Within Subjects Design
Also repeated measures and within groups, each participant (‘subject’) is in both the experimental and control groups or all the treatment conditions (if there is no control group).
Between Subjects Design
Also called independent groups and between groups, each participant (or ‘subject) is randomly allocated to one of two (or more) groups or conditions and provides one score for data analysis.
The order effect
Occurs when participants’ responses in the various conditions are affected by the order of conditions to which they were exposed.
Counterbalancing
A technique used to deal with order effects when using a repeated measures design. With counterbalancing, the participant sample is divided in half, with one half completing the two conditions in one order and the other half completing the conditions in the reverse order.
Attention
Refers to actively focusing on particular information while simultaneously ignoring other information.
What are the three types of attention?
-Sustained Attention
-Selective Attention
-Divided Attention
Sustained Attention
Allows us to fully process information or complete a task.
Example: Watching a movie without needing to pause or rewind to understand the plot.
Selective Attention
Acts as a filter that helps us to prioritise incoming information according to its performance.
Example: Focusing on what one person says and ignoring the sounds of other conversations or stimuli that may distract you.
Divided Attention
Allows us to process multiple sources of information or stimuli more efficiently.
Example: Driving while following directions from your navigation system.
Sensation
Involves receiving sensory information from the environment. This is done via sensory receptors (specialised cells in your sense organs).
3 steps of sensation
-Reception
-Transduction
-Transmission
Reception
The process of detecting incoming sensory information.
Transduction
The process by which the information is converted into a form which can travel along neural pathways to the brain as neural impulses.
Transmission
Involves sending the information to the brain.
Eg. Vision:
Optic nerve - thalamus - visual cortex
Perception
Refers to the process of selecting, organising, and interpreting sensory information.
3 stages of perception
-Selection
-Organisation
-Interpretation
Selection
The process of attending to certain sensory stimuli and excluding others (conscious and unconscious selection).
Organisation
The process of regrouping sensory stimuli to form meaningful understanding.
Interpretation
The process in which information is given meaning to that it can be understood. Bringing together incoming sensory information and existing knowledge.
Bottom-up processing
A stimulus driven process that entirely relies on raw sensory information and no past knowledge. Used when information is unfamiliar or highly complex.
Top-down processing
Begins with the whole picture. Relies on context, previous knowledge and your expectations. Used when what is being perceived is relatively familiar and less complex.
3 categories of perception principles:
-Gestalt
-Depth cues
-Perceptual constancies
4 Types of gestalt principles
-Figure-ground organisation
-Closure
-Similarity
-Proximity
Figure-ground organisation
We use this principle when we visually organise a scene so that we seperate an object (‘figure’) from the background.
Closure
The perceptual tendency to close-up, fill-in or ignore gaps in an image in order to view an object as a whole.
Similarity
The tendency to perceive parts of a visual image that have similar traits (colours, size, shape, texture) as belonging together as a group or whole.
Proximity
The tendency to perceive parts of a visual image which are positioned close together as belonging together in a group. We group items based on their nearness to each other, in order to create a meaningful whole.
Depth Perception
The ability to accurately estimate the distance of objects and therefore perceive the world in three dimensions.
Depth cues
Are sources of information from the environment, internal and external cues that help us perceive how far away objects are and therefore to perceive depth.
What are the two groups of depth cues?
Binocular and monocular.
Binocular depth cues
Require the use of both eyes working together in order to provide information to the brain about depth and distance.
Convergence
Involves the brain detecting distance from changes in tension in the eye muscles that occur when the two eyes turn inwards to focus on objects that are close.
Retinal disparity
Refers to the very slight difference in the location of the images on the retinas which enables us to make judgements about the depth or distance of an object.
Monocular depth cues
Require the use of only one eye to provide information to the brain about depth and distance, but they also operate with both eyes.
Accommodation
involves the automatic adjustment of the shape of the lens to focus an object in response to changes in how far away the object is.
What are the pictorial cues?
-Linear Perspective
-Interposition
-Relative Size
-Texture Gradient
-Height in the Visual Field
Linear Perspective
is the apparent convergence of actual or imagined parallel lines as they recede into the distance.
Interposition
Also called overlap, occurs when one object partially blocks or covers another, and the partially blocked object is perceived as further away than the object that obscures it.
Texture Gradient
refers to the gradual reduction of the detail that occurs in an object or surface as it recedes into the distance, compared with an object or surface that is close and perceived as fine detail.
Relative Size
refers to the tendency to visually perceive the object that produces the largest image on the retina as being closer, and the object that produces the smallest image on the retina as being further away.