Chapter 5 Flashcards
Why is the perceptual system not concerned with determining an object’s image on the retina?
It’s job is to determine the object out there that created the image
What is the inverse projection problem?
The task of determining the object responsible for a particular image on the retina.
What problems do computers face in object recognition that the human brain is able to do flawlessly?
1) objects are hidden or blurred
- computers have a hard time recognizing partially hidden objects or blurred objects such as faces, while the brain will still be able to make the connection and recognize things.
2)Different viewpoints
- objects can be viewed from all kinds of viewpoints and they look slightly different in every single one of them. It’s not obvious to a computer.
What is viewpoint invariance?
The ability to recognize an object seen from different viewpoints.
Describe perceptual organization.
Process by which elements in a person’s visual field become perceptually grouped and segregated to create a perception.
Incoming stimulation is organized into coherent units such as objects.
Involve two components
- grouping
- segregation
What is grouping in perceptual organization?
Process by which elements in a visual scene are “put together” into coherent units or objects. Ex: going to new york city and your brain is able to group the visual elements to create each building.
What is segregation in perceptual organization?
Works in conjunction with grouping
Process of separating one area or object from another. Ex: seeing two buildings as separate buildings, with borders indicating where they end.
What is the Gestalt approach to perceptual grouping of Gestalt psychologists?
We can understand the Gestalt approach by first considering an approach called structuralism
Structuralism = distinguishes sensations and perceptions. Sensations as analogous to the atoms of chemistry. Just as atoms combine to create complex molecular structures, sensations combine to create complex perceptions.
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Rejected by Gestalt psychologists.
Apparent movement
- illusion of movement by rapidly alternating two slightly different pictures —> How the structuralist’s idea that experience is created by sensations could explain the illusion of movement he observed.
What are the three components of apparent movement?
1) one light flashes
2) There is a period of darkness lasting a fraction of a second
3) The second image flashes
Why don’t we see the darkness in the period of darkness in between two images in apparent movement?
Because our perceptual system adds something during the period of darkness — the perception of an image moving through the space between the flashing lights
What were Wertheimer’s two conclusions from the phenomenon of apparent movement?
1) apparent movement can’t be explained by sensations alone, because there is nothing in the dark space between the flashing lights
2) the whole is different than the sum of its parts, because the perceptual system creates the perception of movement where there actually is none
What are illusory contours?
A shape seemingly created by other shapes with no physical edges present.
Cannot be explained by sensations because there aren’t any sensations along the contours.
What is the proposition of Gestalt psychologists?
Proposed that perception depends on a number of principles of perceptual organization, which determine how elements in a scene become grouped together.
What are the starting points for the principles of organization of Gestalt psychologists?
Things that usually occur in the environment.
Ex: perceive one rope in multiple ropes
This gives to Gestalt’s idea of the principle of good continuation
What is the principle of good continuation?
Points that, when connected, result in straight or smoothly curving lines are seen as belonging together, and the lines tend to be seen in such a way as to follow the smoothest path.
Objects that are partially covered by other objects are seen as continuing behind the covering object.
What is the principle of pragnanz also called the principle of good figure or principle of simplicity?
Every stimulus pattern is seen in such a way that the resulting structure is as simple as possible.
Ex: symbol of the olympics
What is the principle of similarity?
Similar things appear to be grouped together.
Ex: causes circles of the same colour to be grouped together.
Also works for auditory stimuli. Notes of same pitch that follow each other closely in time can become perceptually grouped to form a melody.
What is the principle of proximity or nearness?
Things that are near each other appear to be grouped together
What is the principle of common fate?
Things that are moving in the same direction appear to be grouped together.
Ex: flock of birds all flying together. Flock as a unit.
Also to changes in illumination when elements of our visual field that become lighter or darker simultaneously are perceived as being grouped into a unit
What is the principle of common region?
Elements that are within the same region of space appear to be grouped together.
Ex: things inside ovals will seem to belong together
What is the principle of uniform connectedness?
A connected region of the sale visual properties, such as lightness, colour, texture, or morion, is perceived as a single unit.
Ex: connectedness overpowers proximity —> ovals with circles in them example.
Why are the Gestalt principles still important even if we consider them obvious?
They are the basic operating characteristics of our visual system that determine how our perceptual system organizes elements of the environment into larger units.
What is the approach to studying perceptual segregation by considering the figure-ground segregation?
When we see a separate object, it is usually seen as a figure that stands out from its background, which is called the ground.
Ex: paper on a desk. Surface of desk as ground and paper as figure. If you step backwards you might see the desk as the figure and the wall as the ground.
What is the reversible figure-ground?
It can be perceived alternately either as two dark blue faces looking at each other, in front of a gray background, or as a gray vase on a dark blue background.
