unit 3 - cognitive psych

Explain what it means to interpret scenes based on cues present in those scenes.

This describes the computational approach to the study of perception. Cues in the stimulus such as basic features, linear perspective, and retinal size help us to interpret the size and distance of objects in the environment and also help us to identify those objects.

computational approach to perception

- researchers consider how diff cues in the stimuli can be used to interpret the environment; focus on "what" of perception focuses on cues in the environment as a means of perceiving & interpreting stimuli both bottom-up & top-down processing contribute to object & scene interpretations cues such as linear perspective & retinal image size help us determine the size & distance of objects in the environment - can be misleading at times when we misinterpret stimuli

Gestalt approach to perception

- researchers consider how organizational principles of the world allow us to interpret the stimuli in our environment; focus on "what" of perception the interpretation of a scene applying principles of how the world is organized (top-down processing is key component) perception occurs through applying a set of organizational principles that follow physical processes of the natural environment/world -> when we apply these principles, our perception of a scene is "more than the sum of its parts" 1. similarity: objects are grouped according to similarity 2. proximity: objects are grouped according to their proximity in a scene 3. good continuation: objects are perceived as continuous in cases where it is expected that they would continue 4. closure: objects are perceived as whole even when parts are occluded/missing 5. pragnanz (simplicity): objects are perceived in the simplest way possible suggests that we rely more on top-down processing & our knowledge of the world in the form of organizing principles to help us perceive the world - even in cases where perception is more difficult, these organizational principles can help us view objects in a scene that may be hard to perceive

Perception-Action Approach

- researchers consider the goals of action achieved thru more direct perception; focuses on "what for" aspect of perception; what are the possible AFFORDANCES of this environment? perception and actions are intricately linked; consistent with embodied cognition approach from ch1 we percieve object distance based on the optic flow (closer images move faster & farther ones move slower) & not from 1st representing the image in our minds based on retinal image size blends elements of ecological & representationalist view: ex; know a chair is a chair bc we sit on it but can also identify it as a chair if someone asks us what it is perception is also influenced by possible actions, even when those actions do not need to be performed

Look around your environment and describe some examples of good continuation in the objects around you. You should be able to identify examples on the test.

- says that points that are connected by straight or curving lines are seen in a way that follows the smoothest path; rather than seeing separate lines & angles, lines are seen as belonging together ex; photo of cat in pot -> perceive that the entire body of the cat is lying in the pot even though we can only see part of it; have same perspective for any object that we can only see a portion of ex; see my dog's body lying on the stairs but I don't see his head -> assume head is lying on the stairs also ex; see my brother holding 2 separate ends of a foam roller from behind -> assume the roller is in 1 piece and that he is not holding 2 separate pieces of the roller

Describe the 4 parts of a sensory system

1. sense organs: ears, eyes, nose, tongue, skin 2. receptor cells in each sense organ that receive stimulus energy & convert it to neural signals 3. nerve conduit that carries the neural signal from the sense organ to the brain 4. brain areas that process the neural signals received from the sense organ

ventral stream

A pathway in the brain that deals with the visual information for what objects are; processes "what" information about the environment

Would a perception/action researcher be interested in explaining the moon illustration described in Study Questions 3.2, #5? Why or why not?

A perception/action researcher would only be inter-ested in this illusion in terms of any behaviors it might influence.

What is an affordance?

An affordance is a possibility for behaviors in a given environment.

In what way do illusions illustrate the normal processes of perception?

Because we use cues to interpret stimuli, those cues can sometimes lead to an inaccurate interpretation when they conflict with or are not an accurate representation of the environment.

good continuation

Gestalt principle stating that smooth, flowing lines are more readily perceived than choppy, broken lines our understanding that objects continue even if parts of them are occluded

You see a light approaching on the road at night. According to the likelihood principle, which of the following are you most likely to perceive: a) a deer crossing the road wearing a headlight, b) a UFO, or c) an approaching car?

In this situation, the most likely object causing this stimulus is (c) an approaching car. The likelihood principle states that we interpret stimuli based on the most likely event.

People report a "moon illusion" such that the moon appears larger when it is lower in the sky and closer to the horizon than when it is high in the sky and above us. Using what you learned about the use of cues in this section, why do you think the moon illusion occurs?

One possible explanation of this illusion is that we mis-interpret the size of the moon based on the comparison of retinal images of objects near the horizon (e.g., build-ings and trees that can be seen along with the moon when it is low in the sky). When the moon is high in the sky, there are typically no other objects to compare it with. However, the explanation of the moon illusion is still debated within research in perception so there is no one right answer to this question.

What is the role of receptor cells in perception?

The receptor cells serve the important role of convert-ing stimulus energy (e.g., light, sound waves) to neural signals that can be received and processed by the brain.

How does the Gestalt approach to perception differ from the computational approach to perception?

The Gestalt approach to perception focuses almost entirely on top-down processing in the form of organizational principles of the world that we use to interpret stimuli in the environment. Adding cues or features together, as in the computational approach, is seen as providing an incomplete perception of objects and scenes.

Consider the moon illusion described in Study Questions 3.2 #5. Would the Gestalt approach to perception explain this illusion differently than the computational approach? Why or why not?

The Gestalt approach would provide a different explanation of this illusion because it would not consider cues such as retinal image size to explain the illusion.

In the scene in photo 3.4, describe some cues you can use to determine that the front of the pot is closer to you than the cat.

The retinal image size of the pot is larger than the reti-nal image of the cat. The cat is also higher in the photo; thus, linear perspective may help us determine that it is farther away.

How is top-down processing involved in the Gestalt approach to perception?

Top-down processing is involved in the use of knowl-edge about how the world is organized. We use this knowledge to mentally organize scenes (e.g., by proxim-ity, similarity).

I am looking at the lilac tree bloom outside my window. I immediately imagine going out and smelling the flowers. Explain how my perception of the lilac flowers fits a perception/action approach.

Your perception of imagining going out and smelling the flowers on the lilac tree fits a perception-action approach because this approach not only involves performing actions, but it also involves our perception of possible actions which influences how we behave.

What are the advantages to having a perceptual system that has automatic input of all environmental stimuli but only consciously processes a small portion of those stimuli?

a primary advantage is that we can focus our attention on (or attention can be captured by) any stimuli in the environment because all are being received. Thus, we have the ability to consciously pro-cess any stimulus in our environment.

sensory system

a system that receives and processes input from stimuli in the environment

distal stimulus

an object or event in the outside world; stimulus in the environment

Principle of Pragnanz

an organizational principle that allows for the simplest interpretation of the environment

affordance

behaviors that are possible in a given environment ex; can I pass through that space?; can I use this stick to hammer in that nail?

dorsal stream

pathway in the brain that processes "where" information about the environment

How do perception/action approaches to cognition differ from computational approaches?

perception/action approaches consider perception as a means to achieve behavioral action

Gestalt Psychology

perspective in psychology that focuses on how organizational principles allow us to perceive & understand the environment

proximal stimulus

stimulus registered by sensory receptors; stimulus in the mind

theory of unconscious inference

the idea that we make unconscious inferences about the world when we perceive it - we use our top-down processing to perceive & interpret the environment unconsciously

bottom-up processing

understanding the environment thru basic feature identification & processing perception is conducted starting w the most basic units/features of a stimulus & adding the parts together to understand & identify a coherent, whole object. -ex; forming letters -> adding letters to each other -> creating words -> adding words to create sentences etc - ex; identifying geons (3D pieces) of objects & matching them up to objects stored in our memory to identify the whole object

top-down processing

understanding the environment thru global knowledge of the environment & its principles when we use our knowledge of objects to aid in our perception; use basic feature cues in the environment to perceive & also our knowledge of the world to interpret those cues - sometimes our proximal stimulus in our mind doesn't match our distal stimulus -> mislead ourselves