Visual Perception Lecture PDF

Visual Perception Christopher Gade, PhD What do you see?  Now that we’ve discussed how our sensory neurons and organs generate neural messages for our brains to Perception process, we’ll turn our attention to of Visual how our mind is able...

Visual Perception Christopher Gade, PhD What do you see?  Now that we’ve discussed how our sensory neurons and organs generate neural messages for our brains to Perception process, we’ll turn our attention to of Visual how our mind is able to make sense of the information that is being sent to it Information To simplify this topic, we’ll focus our attention on the topic of vision  Perceptual psychologists study the concept of visual perception through different topics – Color, size, depth, motion, angles, shape But how do we make sense of the stimuli around us? – The constructivist approach – our expectations of the world around us, A Debate Within what we focus on, and our the Field manipulations of the information presented to us shapes what we perceive (top-down processing) – The ecological approach – what we perceive in our environment can be explained entirely through the characteristics of the stimuli in our environment that our sensory organs are processing (bottom-up processing)  Examining This Debate Through Color Vision Discoveries The Young-Helmholtz Trichromatic Theory of Color Vision (support for the ecological approach) – We have three types of cells that are sensitive to different frequencies of color – The ratio of response of these cells lets us determine the color of the stimulus that we are examining  Proof: Color Vision Deficiencies Trichromats – most of us have three types of cones (L-cones, M-cones, and S- cones) The inability to detect different colors or differences between colors comes from 3 sources – Color insensitivity versus color blindness Problems with This Theory Light and dark contrast issues The afterimage effect  The Opponent Process A New Component to Color Theory of Color Vision (also supported by the Vision ecological approach…eventually) – Our vision of color is also determined by a contrast between opposing colors Red-Green, Blue- Yellow, Black-White – Linked to a message from the bipolar and ganglion cells But is this really how all perception works? Does that Mean that the Ecological Approach is All We Need? Color constancy – we determine color through more than the frequencies being projected, we also use ambient lighting and surrounding colors – Note: B=D, A≠D, B≠C The retinex theory of color vision– our expectations and anticipation of visual information are used to determine color Don’t Trust Me?  The Constructivist Growth Gestalt Psychologists – a group that attempts to understand psychological phenomena by viewing them as organized and structured wholes rather than the sum of their constituent parts “The whole is greater than the sum of all of its parts” – Started in the early 1900’s, but still exist in some form today – Gestalt laws/principles of perception – Transition from laws and principles to optical illusions The Implications of The Mind’s Impact: We See More/Less than What’s There  Visual Illusions: Another Way to Appreciate the Value of Interpretation So we can study how we interpret stimuli in our world by generating rules… great. Is there another way that we can better understand perception? What if we study perception by looking at errors of the tools we use? Some study situations that trick the mind to get a better understanding of the topic The Muller-Lyer Illusion The Ponso Illusion The Ames Room  Revisiting the Debate So who is right, constructivist or ecological psychologists??? Research seems to indicate that a big portion of our perception does come solely from the information processed by our sensory organs HOWEVER, there is also considerable evidence that our mind and expectations play a critical role in our sensory experiences This implies that the constructivist view is a very important part of perception It also means that we—as psychologists—must tackle perception from several angles if we want to fully appreciate this process