Test 2 - 'Visual Perception' Flashcards
Binocular depth cues
- Retinal disparity
- Convergence
Monocular depth cues
- linear perspective
- interposition
- texture gradient
- relative size
- height in the visual field
- pictorial depth cue
- accommodation
Retinal disparity
The binocular depth cue which arises as the brain compares and contrasts the two slightly different images obtained because of the distance between the two eyes.
Convergence
A binocular cue for depth perception. The automatic turning of the eyes inward as we watch and object approaching.
Linear perspective
A monocular (pictorial) depth cue interpreted by Leonardo da Vinci, that parallel lines appear to converge as they retreat into the distance.
Interposition
A monocular (pictorial) cue, in which objects further away from the observer are partially obscured by those in the foreground. Also called ‘overlap’ and ‘occlusion’
Texture gradient
A monocular (pictorial) cue, in which texture in the foreground is seen in more fine detail than that further away.
Relative size
A pictorial depth cue based on our tendency to perceive the object producing the largest retinal image as being the nearest, and the object producing the smallest retinal image as being the farthest.
height in the visual field
A pictorial depth cue that shows depth by portraying objects further away as being closer to the horizon.
Pictorial depth cue
A monocular depth cue used by artists to create a 3D perception of something that exists on a 2D surface.
accommodation
The process by which the ciliary muscles of the eye change the curvature of the lens to focus an image on the retina.
Electromagnetic spectrum
400-700 nanometers
Rods
- There are about 125 million in each eye.
- responsible for vision in low light
- peripheral vision
- black and white
Cones
- there are about 6 500 000 in each eye.
- responsible for detail
- colour vision
Electromagnetic energy vs Electrochemical energy
The electromagnetic energy (light energy) is converted by the rods and cones into electrochemical nerve impulses.
6 stages in the visual perception process
- Reception
- Transduction
- Transmission
- Selection
- Organisation
- Interpretation
Reception
Light enters the eye through the cornea, a tough transparent tissue covering the front of the eye.
Transduction
The electromagnetic energy that we know as light energy is converted by the rods and cones into electrochemical nerve impulses.
Transmission
the next task for the rods and cones is to send the nerve impulses along the optic nerve to the primary visual cortex in the occipital lobes.
Selection
We can’t possibly pay attention to all the millions of stimuli that enter the eye at the same time, so we pick out the ones that are important to us and pay attention to those.
Organisation
When visual information reaches the brain (the visual cortex), it is reorganised so that we can make sense of it.
Interpretation
This is the process whereby the visual stimulus/ object is given meaning.
Random allocation
A subject selection procedure where all participants who have been selected for an experiment have an equal chance of being in the experimental group or the control group.
Random sampling
a sampling procedure in which every member of the population has an equal chance of being selected.
Convenience sampling
picking whoever is available at the time.
Stratified sampling
Dividing the population into categories and selecting at random in proportions equivalent to population.
Ethics in research
- the role of the experimenter
- participants rights
- confidentiality
- voluntary participation
- withdrawal rights
- informed consent
- deception in research
- debriefing
Role of the experimenter
The researcher must always act in a professional manner, making sure that the best interests of the participants, and of society in general, are met.
Participants rights
Researchers must always maintain respect for the participants.
Confidentiality
Participants must not be identified in any way in terms of test results, their involvement in the study or any other confidential data.
Voluntary participation
Participants have the right to refuse to take part in a study. There must not be any pressure to take part in a study.
Withdrawal rights
Participants have the right to leave a study at any stage. Regardless of the possible effects on the results.
Informed consent
Participants must be given information about the study before they agree to take part.
Deception in research
This is only permitted if the results would be confounded if the participants had much information before taking part in the study.
Debriefing
Debriefing occurs after the completion of the sty and participants are told the results and conclusions of the study.
Visual illusion
They are mistaken perceptions of visual stimuli. We may misjudge length curvature, position, speed or direction in a visual illusion.
Ames room illusion
The Ames room illusion shows that we maintain shape constancy (of a room) at the expense of size constancy. The Ames room is not really rectangular, but because of our lifetime of experience with rectangular rooms, we perceive it to be bounded by right-angles. In fact the ‘smaller’ person is simply twice as far from the observer as the ‘larger’ person.
Muller Lyer illusion
It involves the ‘misapplication of size constancy’. We mentally make a 3D from of each figure, using familiar features of buildings to do so. This causes the observer to perceive the arrow-headed line as the leading vertical edge of a building’s outer wall. We therefore perceive the feather-tails to be longer.
Hypothesis
A hypothesis is a clear statement predicting how changes in the independent variable(s) will affect the value of the dependent variable(s). It is an educated guess.
Independent variable
Population
And
Dependent variable
Independent variable
It is deliberately manipulated or varied in some way by the experimenter.
Dependent variable
It is the property that is measured in the research.
Extraneous variable
It is a variable other than the IV that could potentially alter the value of the DV.
Experimental variable
The group of research participants which is exposed to the independent variable.
Control group
The group of research participants which is not exposed to variations in the independent variable.
Population
The group of people about which we wish to draw conclusions. E.g. Adult drivers in Melbourne
Sample
The members of the population that have been chosen to take part in the research. E.g. 20 students
Qualitative data
Refers to the descriptions of the characteristics of what is being studied.
Quantitative data
Refers to measurement- numerical information about the variables being studied.
Mode
is the most commonly occurring score in the dataset.
Median
the score that occurs exactly halfway between the lowest and the highest score.
Mean
the average of all the scores, calculated by adding up all the scores and dividing that total by the number of scores.
Longitudinal study
a form of repeated measures design, where the same participants are investigated over a period of time.
Cross-sectional study
a form of independent group design, where data is collected at one time from participants of all ages and different age-groups and compared
Perceptual set
a predisposition to attend to certain aspects of the visual scene, or to interpret stimuli in a particular way.
Influential factors of a perceptual set.
- Previous experience
- Context
- Motivation
- Emotion
Steps of psychological research
1 Identify the area of research and form a research aim.
2 Collect information
3 Identify the research question and formulate a hypothesis.
4 Design a research method to test the hypothesis
5 Collect and analyse the data
6 Draw conclusions – accept or reject the hypothesis
7 Report findings
8 Test the conclusion
absolute threshold
The minimum amount of physical energy needed for an observer to perceive a visual stimulus in ideal conditions 50 per cent of the time.
Thresholds for each sense
- Hearing: the ticking of a watch 6 m away
- Smell: one drop of perfume in a large house
- Taste: one teaspoon of sugar dissolved in 10L of water
- Touch: the wing of a fly falling on the cheek from a height of 1 m
- Vision: the flame of a candle 50km away on a dark, clear night
Thresholds for each sense
- Hearing: the ticking of a watch 6 m away
- Smell: one drop of perfume in a large house
- Taste: one teaspoon of sugar dissolved in 10L of water
- Touch: the wing of a fly falling on the cheek from a height of 1 m
- Vision: the flame of a candle 50km away on a dark, clear night
Perceptual constancy
Enable us to maintain a stable perception of a stimulus, although the image on the retina may change
Size constancy
we maintain constant perception of an objects size, even though the size of the image on the retina alters as the object moves nearer and further from us.
Gestalt
A German word meaning ‘good form’.
It explains perception organisation through ‘holistic’ theories, of which perception is achieved through top-down processing.
The Phi Phenomenon
- makes cartoons and movies
- one still picture after another gives us the impression of movement on the screen.
Figure Ground organisation
the part of the visual field being attended to and focused on is the figure and its surroundings are the ground.
Closure
we perceive an object as being whole, despite it being incomplete.
Similarity
the individual parts of a stimulus pattern are similar in size, shape or colour.
Proximity
the individual parts of a stimulus pattern are close to each other.
Shape Constancy
an object is perceived to maintain its known shape despite the changing perspective from which it is observed.
