3.1 Nature of perceptions Flashcards
What is perception definition?
Conscious experience that results from stimulation of the senses.
Diagram of Emma’s situation
Emma begins her run along the beach just as the sun is rising over the sea. She loves this time of day, both because it is cool and because the mist rising from the sand creates a mystical effect. As she looks down the beach, she notices something about 100 metres away that wasn’t there yesterday. “What an interesting piece of driftwood,” she thinks, although it is difficult to see because of the mist and dim lighting (Figure 3.1a). As she approaches the object, she begins to doubt her initial perception, and just as she is wondering whether it might not be driftwood, she realizes that it is, in fact, the old beach umbrella that was lying under the lifeguard stand yesterday (Figure 3.1b). When she realizes this, she is amazed at what has happened. “Driftwood transformed into an umbrella, right before my eyes,” she thinks.
Explaining Emma’s situation illustrating number of things about perception
(1)
- umbrella illustrates how perceptions can change based on added information (Emma’s view became better as she got closer to the umbrella) and how perception can involve a process similar to reasoning or problem solving (Emma figured out what the object was based partially on remembering having seen the umbrella the day before). Emma’s guess that the coiled rope was continuous illustrates how perception can be based on a perceptual rule (when objects overlap, the one underneath usually continues behind the one on top), which may in part be based on the person’s past experiences.
Emma’s siutation demonstrate how:
arriving at a perception can involve a process. It took some time for Emma to realize that what she thought was driftwood was actually an umbrella, so it is possible to describe her perception as involving a “reasoning” process. In most cases, perception occurs so rapidly and effortlessly that it appears to be automatic. But, as we will see in this chapter, perception is far from automatic. It involves complex, and usually invisible, processes that do resemble reasoning, although they occur much more rapidly than Emma’s realization that the driftwood was actually an umbrella.
Emma’s experience also illsutrates
(3)
perception occurs in conjunction with action. Emma is running and perceiving at the same time, and picking up the rope confirms her perceptual notion that indeed it was one continuous piece of cord. This aspect of Emma’s experiences is just like what happens in everyday perception. We are usually moving, and even when we are just sitting in one place watching TV, a movie, or a sporting event, our eyes are constantly moving as we shift our attention from one thing to another to perceive what is happening. We also grasp and pick up things many times a day, whether it is a cup of coffee, a piece of cable, or this book. As we will see in this chapter, perception involves dynamic processes that accompany and support our actions.
Roger looks at about 15 buildings
What can he clearly see?
- Two modern glass buildings infront of some larger ones on the side with similar rows of blue-coloured windows
No trouble telling they are different sets of building
However, looking at tree he releases they are grow between as behind the older buildings at the river side
Roger’s perception of the buildings
is it easy to come and perceive the buildings?
- Naturally comes to him and require little effort
- He knows he is looking at different buildings
- He knows because of the pattern of light and dark creating a scene on the retina
What is retina?
structure that lines the back of the eye and contains the receptors for seeing.
What to use to tell humans and computers apart?
- Captchas
- Turning test to tell humans and computer apart
- Captchas usually consist of a few numbers or letters that are rotated and which often depicted with some lines or other symbols in the background
What are captchas abbreivation?
Completely automated public
Development of computer vision systems that are able to make fine-grained judgements to recognise specific species of animals and plants
However, why is there performance still so poor?
Their performance is still far below what humans routinely achieve
Why is computer’s perception not close to human’s perception?
An example by Parkhi Vedaldi Zisserman and Jawahar
- Programs have been developed to tell the difference between cats and dogs ith about 90% accuracy and can identify different breeds of cats and dogs with 60% accuracy
- Difficult task involving complex programs and a lot of training on different images
- Problem is many of current computer programs is that even though they may be able to identify some objects, they often make errors that human never make such as calling camera lens cover/teapot a tennis ball
Another object that recieved a lot of attention from computer vision researchers is the human face
Programs been developed that can determine just as well as humans can whether two faces are seen straight on are the same or different people?
What is the results?
(O’Toole,
- However, when one of the faces is seen at an angle, as in Figure 3.4c, humans clearly outperform computers. Again, you should ask yourself, why is this the case? What do we do that computers can’t, or what do we possess that computers haven’t?
Which statement about perception is the most accurate?
Perception often involves processing and can change when new information is provided.
Research aimed at developing accurate computer vision systems has
Research aimed at developing accurate computer vision systems has yielded mixed results with some areas of success, although computers make errors that humans would not make.
