Perception 3,3 Flashcards
One purpose of perception is to inform us about what is out there in the environment?
What is the perception foundations?
Of information from the environment
For visual perception this information is light
Diagram of information
explain
Information from the light entering the eye and the electrical signals to the brain is crucial for perceiving any object in the environment
because without it, the object will not be represented in the nervous system
The sequence of events from eye to brain is called bottom up processing
starts at the “bottom” or beginning of the system, when environmental energy stimulates the receptors.
What is bottom up processing?
Processing that starts with information received by the receptors. This type of processing is also called data-based processing.
What else needs to be involved other than the information from light entering eye?
- perception needs more information than what is provided by activation of the receptors and bottom-up processing.
- Perception also involves factors such as a person’s knowledge of the environment, the expectations people bring to the perceptual situation, and their attention to specific stimuli. This additional information is the basis of top-down processing—processing that originates in the brain, at the “top” of the perceptual system (see Figure 3.10).
What is top down processing?
Processing that involves a person’s knowledge or expectations. This type of processing has also been called knowledge-based processing.
Diagram of top donw and bottom up processing?
Figure 3.11
example of top-down processing involved in perceiving objects
- An example of how top-down processing is involved in perceiving objects is illustrated in Figure 3.11. Depending on whether you interpret the central stimulus as a part of a row or a column, you will either perceive it as the letter S (as part of a row of letters) or as the number 5 (as part of a column of numbers).
Infleunce of context has been demonstrated in study by oliva and torrabla 2007
multiple personalities of a blob
- Participants in their study were asked to identify a blurred object in a scene (the “blob”).
- Results showed that even though the “blobs” in all the pictures were identical, they were perceived as different objects (for example, a shoe on a person bending down, or a car or person on the street) depending on its orientation and the context within which they were seen.
How does top down processing influence speech perception?
Watching Spanish TV channel
- If you don’t speak Spanish you won’t understand anything the people are saying. In fact, the dialogue will sound like an unbroken string of sound, except occasionally when a familiar word like gracias or casa pops out.
- Your perception will reflect the fact that the sound signal for speech is generally continuous, and when there are breaks in the sound, they do not necessarily occur between words. You can see this in Figure 3.13 by comparing the place where each word in the sentence begins with the pattern of the sound signal.
What about when sometime understands Spanish watching this?
vs english
perceives this unbroken string of sound as individual, meaningful words in a conversation. Because of their knowledge of the language, they are able to tell when one word ends and the next one begins, a phenomenon called speech segmentation.
listener familiar only with English and another listener familiar with Spanish can receive identical sound stimuli but experience different perceptions means that each listener’s experience with language (or lack of it!) is influencing his or her perception. The continuous sound signal enters the ears and triggers signals that are sent toward the speech areas of the brain (bottom-up processing); if a listener understands the language, that knowledge (top-down processing) creates the perception of individual words.
What is speech segmentation?
The process of perceiving individual words within the continuous flow of the speech signal.
Perception of pain is an example of how top down processing influences
perception
What model sued in 1950s and 1960s to explain pain?
Direct pathway model
How did direct pathway model worked?
pain occurs when receptors in the skin called nociceptors are stimulated and send their signals in a direct pathway from the skin to the brain (Melzack & Wall, 1965). This is a bottom-up process because it depends on stimulation of the receptors
What is definition of direct pathway model?
Model of pain perception that proposes that pain signals are sent directly from receptors to the brain.