Human Perception PDF

Human-Computer Interaction Human perception, attention, memory  Visual Perception Humans are capable of obtaining information from displays varying considerably in size and other features but not uniformly across the spectrum nor at all speeds. Visual Perception...

Human-Computer Interaction Human perception, attention, memory  Visual Perception Humans are capable of obtaining information from displays varying considerably in size and other features but not uniformly across the spectrum nor at all speeds. Visual Perception is the ability to interpret surrounding environment by processing information that is contained in visible light.  Theories Constructive theory: the process of seeing is active; view of the world constructed from info in environment and previously stored knowledge. Ecological theory: perception involves the process of picking up info from the environment; doesn’t require construction or elaboration.  Visual perception How long did it take to recognize the Dalmatian? Only after you knew what you were looking for? After recognizing the Dalmatian, what else could you see? Interpretation of the scene is possible because we know what Dalmatians, trees, etc. look like -- active construction of the image.  Constructivist approach Perception involves intervention of representations and memories not like the image a camera would produce -- instead, a model that is transformed, enhanced, distorted, and portions discarded ability to perceive objects on a screen is a result of prior knowledge and expectations + image on retina  Effect of context on perception When presented with ambiguous stimuli, our knowledge of the world helps us to make sense of it - - same with ambiguous info on computer screen Constructive process also involves decomposing images into recognizable entities: figure and background  Gestalt psychology Believed that our ability to interpret the meaning of scenes and objects is based on innate human laws of organization Gestalt laws of perceptual organization Proximity - dots appear as groups rather than a random cluster of elements Similarity - tendency for elements of same shape or color to be seen as belonging together Closure - missing parts of the figure are filled in to complete it, so that it appears as a whole circle Continuity - the stimulus appears to be made of two lines of dots, traversing each other, rather than a random set of dots Symmetry - regions bounded by symmetrical borders tend to perceived as coherent figures Law of Proximity The law of proximity states that when an individual perceives an assortment of objects they perceive objects that are close to each other as forming a group. This law is often used in advertising logos to emphasize which aspects of events are associated.  Proximity Proximity occurs when elements are placed close together. They tend to be perceived as a group. The nine squares above are placed without proximity. They are perceived as separate shapes. When the squares are given close proximity, unity occurs. While they continue to be separate shapes, they are now perceived as one group. The fifteen figures above form a unified whole (the shape of a tree) because of their proximity. Law of Similarity The law of similarity states that elements within an assortment of objects are perceptually grouped together if they are similar to each other. This similarity can occur in the form of shape, colour, shading or other qualities.  Similarity Similarity occurs when objects look similar to one another. People often perceive them as a group or pattern. The example above (containing 11 distinct objects) appears as a single unit because all of the shapes have similarity. Unity occurs because the triangular shapes at the bottom of the eagle symbol look similar to the shapes that form the sunburst. When similarity occurs, an object can be emphasised if it is dissimilar to the others. This is called anomaly. Law of Closure The law of closure states that individuals perceive objects such as shapes, letters, pictures, etc., as being whole when they are not complete. Specifically, when parts of a whole picture are missing, our perception fills in the visual gap.  Closure Closure occurs when an object is incomplete or a space is not completely enclosed. If enough of the shape is indicated, people perceive the whole by filling in the missing information. Although the panda above is not complete, enough is present for the eye to complete the shape. When the viewer's perception completes a shape, closure occurs. Law of Continuity The law of continuity states that elements of objects tend to be grouped together, and therefore integrated into perceptual wholes if they are aligned within an object. In cases where there is an intersection between objects, individuals tend to perceive the two objects as two single uninterrupted entities.  Continuation Continuation occurs when the eye is compelled to move through one object and continue to another object. Continuation occurs in the example above, because the viewer's eye will naturally follow a line or curve. The smooth flowing crossbar of the "H" leads the eye directly to the maple leaf.  Figure and Ground The eye differentiates an object form its surrounding area. A form, silhouette, or shape is naturally perceived as figure (object), while the surrounding area is perceived as ground (background). Balancing figure and ground can make the perceived image more clear. Using unusual figure/ground relationships can add interest and subtlety to an image. Figure Ground  Figure The word above is clearly perceived as figure with the surrounding white space ground. In this image, the figure and ground relationships change as the eye perceives the form of a shade or the silhouette of a face. This image uses complex figure/ground relationships which change upon perceiving leaves, water and tree trunk. Optical illusions Try to count the number of black dots on the image below. Two Face Optical Illusion Are the lines below straight or are they curved? It's a spiral, right? Look carefully at the center circles on both the left and right. Which circle is bigger?  How many legs does this elephant have? Find what is wrong in the picture.