I. Sensing the World – Basic Principles
* Bottom-up processing suggests that we attend to or perceive elements by starting with the smaller, more fine details of that element and then building upward until we have a solid representation of it in our minds. * Top-Down Processing states that we form perceptions (or focus our attention) by starting with the larger concept or idea (it can even be the concept or idea of an object) and then working our way down to the finer details of that concept or idea. A. Thresholds
* An Absolute Threshold is the lowest amount of stimulus needed to notice it 50% of the time. * For example, you turn down the radio to a point where you only hear the faint sound half the time. Then that loudness (decibel) is your absolute threshold for sound. * Signal detection theory predicts when we will detect weak signals (measured as our ratio of “hits to “false alarm”). * It seeks to understand why people respond differently to the same stimuli, and why the same person’s reactions vary as circumstances change. * In the studies of Warm & Dember, 1986, that people’s ability to catch a faint signal diminishes after about 30mins. But this diminishing response depends on the task, on the time of day, and even on whether the participants periodically exercise. * Subliminal stimulation offer recordings that supposedly speak directly to our brains to help us. * Subliminal: below one’s absolute threshold for conscious awareness * Priming: the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory or response. * In 1992, Greenwald conducted 16 double-blind experiments evaluating subliminal self-help tapes. His results were uniform: Not one had any therapeutic effect. * Difference threshold, a.k.a. noticeable difference/jnd, is the lowest difference you can detect between 2 stimuli 50% of the time. * For example, if you add 1ounce to a 10-ounce weight, you will detect the difference; ass 1ounce to a 100ounce weight and you probably will not. * Weber’s Law states that two stimuli must differ in percentages or ratios, not amount, for a person to detect it (jnd).
B. Sensory Adaption
* Lowered sensitivity due to constant exposure from a stimulus. For example, when you go into someone’s house you notice an odor…but this only lasts for a little while because sensory adaptation allows you to focus your attention on changing environment; it is irritating to be constantly reminded that your foot is in contact with the floor. II. Vision
A. The stimulus input: Light Energy
* Transduction is the conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret. * Light is composed of electromagnetic waves with Wavelengths (distance from one peak to another peak on a wave) and Amplitudes (height of the wave) * Wavelength is the distance from the peak of one light or sound wave to the peak of the next. * The wavelength determines its hue - The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, and so forth. B. Visual formation processing
* The feature detector cells found in the cortex derive their name from their ability to respond to a scene’s specific features – to particular edges, lines angles, and movements. * Our brain engages to parallel processing which is doing multiple things at once; the brains natural mode of information processing for many functions, including vision. * Jennifer Boyer and her colleagues showed in 2005 the studies of people using magnetic impulse to shut down the brain’s primary visual cortex area. Temporarily disabled people showed a horizontal or vertical line, or a red or green dot. Without seeing anything,...