Visual Perception - Cognitive Psychology, Slides of Cognitive Psychology

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Group 2

Visual

Perception

Presented by: Ariane Basadre Charlene Pabon Joshua Aranes

Visual Perception

 (^) Perception-is the set of processes by which we recognize, organize, and make sense of the sensations we receive from environmental stimuli.  (^) From Sensation to Representation  (^) • We do not perceive the world exactly as our eyes see it. Instead, our brain actively tries to make sense of the many stimuli that enter our eyes and fall on our retina. Objects look different depending on the perspective a.) They look about the same size, as they in fact are. b.) the image in their retina makes them seem to be of different heights, and it is only through further processing that we can pinpoint they are the same size. Click to add text

Seeing Things That Are not There, or Are They?

• To find out about some of the phenomena of perception, psychologists often study situations that pose problems in making sense of our sensations.
• Mental percept—that is, a mental representation of a stimulus that is perceived. Dallenbach’s cow

Elusive Triangles: Real or Illusions?

**- Ganglion cells- process visual information that begins as light entering the eye and transmit it to the brain via their axons, which are long fibers that make up the optic nerve.

• Optic Nerve-transmits electrical impulses from your eyes to your brain. Your brain processes this sensory information so that you can see.**
• Bipolar cells- are one of the main retinal interneurons and provide the main pathways from photoreceptors to ganglion cells, the shortest and most direct pathways between the input and output of visual signals in the retina.
• Photoreceptors-are specialized neurons found in the retina that convert light into electrical signals that stimulate physiological processes. Signals from the photoreceptors are sent through the optic nerve to the brain for processing. Two kinds of Photoreceptors
• Rods- are long and thin photoreceptors. They are more highly concentrated in the periphery of the retina than in the foveal region. The rods are responsible for night vision and are sensitive to light and dark stimuli.
• Cones- are short and thick photoreceptors and allow for the perception of color. They are more highly concentrated in the foveal region than in the periphery of the retina.

How do we make sense of what we see?

Bottom up Theories

 (^) • Describe approaches where perception starts with the stimuli whose appearance you take in through your eye. Four bottom up theories Direct Perception  (^) • According to Gibson’s theory of direct perception, the information in our sensory receptors, including the sensory context, is all we need to perceive anything. As the environment supplies us with all the information we need for perception, this view is sometimes also called ecological perception.

 (^) In Oliver Selfridge’s Pandemonium Model, there are four kinds of demons: image demons, feature demons, cognitive demons, and decision demons.

• image demons-receive a retinal image and pass it on to
• Feature demons. Each feature demon calls out when there are matches between the stimulus and the given feature. These matches are yelled out at demons at the next level of the hierarchy,
• Cognitive (thinking) demons. The cognitive demons in turn shout out possible patterns stored in memory that conform to one or more of the features noticed by the feature demons.
• Decision demon listens to the pandemonium of the cognitive demons. It decides on what has been seen, based on which cognitive demon is shouting the most frequently (i.e., which has the most matching features).

Recognition-by-Components Theory

• According to Biederman’s recognition-by-components (RBC) theory, we quickly recognize objects by observing the edges of them and then decomposing the objects into geons. The geons also can be recomposed into alternative arrangements. Top Down Theories
• According to which perception is driven by high-level cognitive processes, existing knowledge, and the prior expectations that influence perception (Clark, 2003). Constructive perception
• the perceiver builds (constructs) a cognitive understanding(perception) of a stimulus. The concepts of the perceiver and his or her cognitive processes influence what he or she sees. The perceiver uses sensory information as the foundation for the structure but also uses other sources of information to build the perception. This viewpoint also is known as intelligent perception because it states that higher-order thinking plays an important role in perception. It also emphasizes the role of learning in perception (Fahle, 2003). According to constructivists, during perception we quickly form and test various hypotheses regarding percepts. The percepts are based on three things:

This stability can be achieved by means of establishing the major and minor axes of the object, which then serve as a basis for defining further properties of the object. Both positions can account for how the author represents a given object and its parts. The Perception of Groups—Gestalt Laws Perception helps us make sense of the confusing stimuli that we perceive in the world. One way to bring order and coherence into our perception is our ability to group similar things

 (^) Perceive visual arrays in ways that most simply organize the disparate elements into a stable and coherent form. Stop for a moment and look at your environment. You will perceive a coherent, complete, and continuous array of figures and background. You do not perceive holes in objects where your textbook covers up your view of them. You probably first will notice the light-colored lettering of the word figure. We perceive this light colored lettering as the figure against the darker ground. But if you take a closer look, you can see that the darker surrounding actually depicts the word “ground.

 (^) Two Different Pattern Recognition Systems  (^) First - System specializes in recognition of parts of objects and in assembling those parts into distinctive wholes (feature analysis system).  (^) Second - system (configurational system) specializes in recognizing larger configurations. It is not well equipped to analyze parts of objects or the construction of the objects. But it is especially well equipped to recognize configurations. BELIEVE IT OR NOT DO TWO DIFFERENT FACES EVER LOOK THE SAME TO YOU? Red - personality as opposed Green – personality (even if they all are of the same race)

Depth perception may depend upon more than just the distance or depth at which an object is located relative to oneself

. The perceived distance to a target is influenced by the effort required to walk to the location of the target (Proffitt et al., 2003, 2006). People with a heavy backpack perceive the distance to a target location as farther than those not wearing a heavy backpack. The Neuroscience of Depth Perception These neurons are, as one might expect, referred to as binocular neurons The neurons integrate incoming information from both eyes to form information about depth.