The Visual Perceptual Process and Experimental Design
According to Gibson (1969), the human visual perceptual process begins from global processing to local processing. This is based on the principle of global precedence. In other words, the human brain firstly processes information globally before processing it locally. For example, when we look at a scene, our brain will first process the global information such as the general shape, color, and size of objects in the scene before processing the local information such as the details of the objects.
The purpose of this essay is to discuss the visual perceptual process and experimental design and development related to perception. In particular, this essay will discuss global and local processing, conflict and attention, simple patterns, latencies, and recognition.
2. The visual perceptual process
2.1 Global processing
As mentioned above, global processing is the first stage of visual perception. According to Blakemore and Cooper (1970), global processing is defined as “the ability to see the whole pattern rather than its individual parts” (p. 291). Global processing allows us to see the overall form or gestalt of an object or scene. For example, when we look at a square, we see it as a square even if it is made up of smaller squares. This is because our brain can globally process the smaller squares into a square gestalt.
Global processing is important because it allows us to see the world in terms of simple shapes and forms. These shapes and forms are called gestalts which are “the combination of parts that actually occur in an object or scene” (Blakemore & Cooper, 1970, p. 291). For example, we can see a chair as a combination of four legs, a seat, and a backrest. We cannot see these parts individually but only as a gestalt. Without global processing, we would not be able to see complex objects or scenes as gestalts but only as a collection of individual parts.
2. 2 Local processing
Local processing is the second stage of visual perception. According to Blakemore and Cooper (1970), local processing is defined as “the ability to see the individual parts rather than the whole pattern” (p. 291). Unlike global processing which allows us to see gestalts, local processing allows us to see individual parts or details of an object or scene. For example, when we look at a square made up of smaller squares, we can see each small square individually as well as the overall square gestalt.
Localprocessing is important because it allows us to see details that we would not be able to see with global processing alone. For example, when looking at a chair, we can use local processing to see details such as the texture of the seat or the carving on the legs. Localprocessing also allows us to identify objects even when they are partially occluded by other objects. This is because our brain can use local features to recognize an object even when its global form is not visible (Rensink & Cavanagh, 2001).
2. 3 Conflict and attention
Conflict occurs when there is more than one interpretation for what we are seeing (Blakemore & Cooper, 1970). For example, when we look at an Ambiguous figure such as the Necker cube, our brain can interpret it in two ways: as a cube seen from the front or as a cube seen from the back. This conflict between interpretations is called perceptual rivalry (Blakemore & Cooper, 1970).
Attention is needed to resolve perceptual rivalry (Blakemore & Cooper, 1970). For example, when we look at an Ambiguous figure such as the Necker cube, our brain will initially see it as one interpretation (e.g. a cube seen from the front) but then attention will shift to the other interpretation (e.g. a cube seen from the back). This shifting of attention is called successive approximation (Blakemore & Cooper, 1970).
3. Experimental design and development
3.1 Simple patterns
One way to study global and local processing is to use simple patterns such as line drawings of shapes. For example, in the study by Kanizsa (1979), participants were shown line drawings of shapes such as a square made up of smaller squares. The participants were then asked to report what they saw. The results showed that participants were more likely to report seeing the global gestalt (e.g. a square) when the line drawing was simple and the local elements were close together. However, when the line drawing was more complex or the local elements were further apart, participants were more likely to report seeing the individual local elements (e.g. small squares) rather than the global gestalt. These results suggest that global processing is more efficient for simple patterns with close together local elements but less efficient for complex patterns with further apart local elements.
3. 2 Latencies
Another way to study global and local processing is to measure reaction times (RTs) to different kinds of stimuli. For example, in the study by Duncan and Humphreys (1989), participants were shown either global or local stimuli such as a square made up of smaller squares. The participants were then asked to respond as quickly as possible to the stimulus by pressing a button. The results showed that participants were faster to respond to global stimuli than local stimuli. This suggests that global processing is faster than local processing because it does not require attention to shift between different interpretations of the stimulus.
3. 3 Recognition
Recognition memory is another way to study global and local processing. Recognition memory refers to our ability to remember previously seen objects or scenes (Eysenck & Keane, 2015). For example, in the study by Biederman et al. (1982), participants were shown pictures of common objects such as cars or houses and then asked to identify them from a lineup of pictures including both old and new pictures of the same object category. The results showed that participants were better at identifying an object when they had seen it before (i.e. old pictures) than when they had not seen it before (i.e. new pictures). This suggests that our brains can globally process an object and then store it in memory for later recognition.
In conclusion, this essay has discussed the visual perceptual process and experimental design and development related to perception…