DIFFERENCE threshold - The smallest level of added or reduced stimulation required to sense that a change in stimulation has occurred. - It is also called a just noticeable difference. 4 Weber’s Law - It states that a just noticeable difference is a constant proportion of the intensity of an initial stimulus. - The relationship between changes in the original value of a stimulus and the degree to which a change will be noticed. - Weber’s law helps to explain why a person in a quiet room is more startled by the ringing of a phone than a person in an already noisy room. 5 Adaptation - It is an adjustment in sensory capacity after prolonged exposure to unchanging stimuli. - Adaptation occurs as people become accustomed to a stimulus and change their frame of reference. - Jumping into a cold lake may be temporarily unpleasant, eventually the person will get used to the temperature. 6 vision - Optic Nerve: A bundle of ganglion axons that carry visual information to the brain. - Feature Detection: Nobel Prize winners David Hubel and Torsten Wiesel discovered that many neurons in the cortex are extraordinarily specialized, being activated only by visual stimuli of a particular shape and pattern – a process known as feature detection. They found that some cells are activated only by line of particular width, shape or orientation. Other cells are activated only by moving, as opposed to stationary, stimuli. 7 Hearing - Sound: is the movement of air molecules brought about by a source of vibration. Sounds travel through air in wave patterns similar in shape to those in water. - Eardrum: The part of the ear that vibrates when sound waves hit it. The more intense the sound, the more the eardrums vibrates. - Inner Ear: It is the portion of the ear that changes the sound vibrations into a form in which they can be transmitted to the brain. 8 Smell - Although many animals have keener abilities to detect odors than human do, the human sense of smell (olfaction) permits them to detect more than 10,000 separate smells. - Results of ‘sniff tests’ have shown that women generally have a better sense of smell than men do. - The sense of smell is sparked when the molecules of a substance enter the nasal passages and meet the receptor neurons of nose, which are spread across the nasal cavity. - More than 1,000 separate types of receptors have identified on those cells so far. 9 Taste - The sense of taste (gustation) involves receptor cells that respond to four basic stimulus qualities - Sweet -Sour - Salty - Bitter - A fifth category also exists, known as ‘Umami’, which involves food stimuli that contain amino acids. - There are 10,000 taste buds on the tongue and other parts of the mouth. - Taste buds wear out and are replaced every ten days. 10 The skin Senses - Skin senses refer to the senses of touch, pressure, temperature and pain. They play a critical role in survival, making us aware of potential danger to our bodies. - Most of these senses operate through nerve receptor cells located at various depths throughout the skin, distributed unevenly throughout the body - Gate control theory of pain: According to this theory, particular nerve receptors in the spinal cord lead to specific areas of the brain related to pain. When these receptors are activated because of an injury or problem with a part of the body, a ‘gate’ to the brain is opened, allowing us to experience the sensation of pain. 11 The gestalt law of organization - A series of principles that describe how we organize bits and pieces of information into meaningful wholes. - A group of German psychologists who studied patterns or gestalts, discovered a number of important principles that are valid for visual stimuli – 1. Closure: We enclosed group elements to form enclosed or complete figures rather than open ones 12 The gestalt law of organization.. 2. Proximity: We perceive elements that are closer together as grouped together. 3. Similarity: Elements that are similar in appearance we perceive as grouped together. 4. Simplicity: When we observe a pattern, we perceive it in the most basic, straight forward manner we can 13 Top-down & Bottom-up processing…. Ca_ yo_ re_d t_is _ent_en_e w_ic_ ha_ ev_ry _hi_d l_tt_r m_ss_ng? The fact that you were probably able to recognize such an imprecise stimulus illustrates that perception proceeds along two different avenues, called to-down processing and bottom-up processing. 14 - In top-down processing, perception is guided by higher level knowledge, experience, expectations and motivations. - You were able to figure out the meaning of the sentence with the missing letters because of your prior reading experience 15 Top-down Processing Bottom-up Processing - Perception that consists of the progression of recognizing and processing information from individual components of a stimuli and moving to the perception of whole. - Example: a bottom-up approach would claim that in order to form a percept of a cat for instance we basically have an internal Polaroid picture of a cat in our head. - To put it another way, bottom-up processing does not require any thinking, while top-down processing necessarily implies an active mind. 16 Perceptual Constancy…. - The tendency of animals and humans to see familiar objects as having standard shape, size, color, or location regardless of changes in the angle of perspective, distance, or lighting. - Perceptual constancy is responsible for the ability to identify objects under various conditions, which seem to be “taken into account ” during a process of mental reconstitution of the known image. 17 Perceptual Constancy - For example, snow appears white in the low illumination of moonlight, as well as in sunlight 800,000 times as bright. 18 19
Posted on: Fri, 07 Mar 2014 14:50:44 +0000
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