Sensation and Perception Sensory Thresholds and Psychophysics Sensation occurs when sensory areas in the cerebral cortex receive nerve impulses, usually when body sensors such as the touch receptors of the skin are stimulated. Sensation must be distinguished from perception, which is based on the interpretation of patterns of sensation.
Sensation and Perception Sensory Thresholds and Psychophysics Sensation occurs when sensory areas in the cerebral cortex receive nerve impulses, usually when body sensors such as the touch receptors of the skin are stimulated.
Sensation must be distinguished from perception, which is based on the interpretation of patterns of sensation. Perceptions are what your brain makes of those sensory patterns. Under some conditions more than one reasonable interpretation of the same sensory pattern is possible, and in those cases each possible interpretation may give rise to a different perception.
For example, in the necker cube, a single pattern of lines gives rise to two alternate perceptions, depending on which surface of the cube the brain "decides" is closer.
We'll start by reviewing some of what we know about sensation. In particular, we'll be focusing on sensory thresholds. Sensory Thresholds The first systematic studies of sensory thresholds were conducted by physiologist Ernst Weber at the University of Leipsig in Leipsig, Germany, the same university where Wilhelm Wundt would later transform psychology into an experimental science.
Weber's experiments were designed to determine sensory thresholds, of which there are two types: Sensation color and absolute threshold correct threshold -- the minumum intensity of a stimulus that one can detect Difference threshold -- the minimum difference in intensity between two stimuli that one can detect.
The Absolute Threshold If you've ever had a standard hearing test, you've experienced the testing for absolute thresholds.
Typically this involves listening to various pitches of tone through earphones. You are given a button to hold and are told to press the button until you hear a tone, then release the button until the tone fades away, then press the button until you hear it again, and so on.
The intensity at which you "lose" and regain the tone is your absolute threshold for that particular tone. Such a stimulus is termed subliminal below threshold; the German word for threshold is limen. The Difference Threshold As with the absolute threshold, Weber defined the difference threshold statistically.
The difference threshold is the average of the two differences between the comparison stimuli and the standard. Weber noticed that the difference threshold is a constant proportion of the initial stimulus intensity.
He expressed this relationship in a formula now called Weber's Law: Note that the smaller the number, the better able you are to discriminate small differences, or in other words, the more sensitive you are to a change in intensity.
Gustav Fechner and Psychophysics About 20 years after Weber's pioneering work, another professor at the University of Leipsig, Gustav Fechner, decided to determine the relationship between the physical intensity of a stimulus for example, the sound pressure level of a sound wave and the psychologically perceived intensity in this case, the loudness of the resulting sound.
Fechner called the field of study than examines the relationship between the physical stimulus and its psychological representation Psychophysics. After independently rediscovering Weber's Law, Fechner went Weber one better by showing that, with Weber's Law and the addition of a simple and reasonable assumption, one could determine the relationship between physical and psychological intensity he was seeking.
Fechner called the difference threshold by a different name: Fechner simply assumed that, psychologically speaking, all JNDs seem like the same amount of change in stimulus intensity.
Fechner assumed that an increase of 2 grams from seems like the same increase in weight as an increase of 4 grams from grams.
It follows from this assumption and Weber's Law that the perceived intensity of a stimulus will change in proportion to the logarithm of the physical stimulus intensity, and not in direct proportion to the physical stimulus intensity as might have been expected.
This implies that at the high end of the intensity scale, we become almost but not quite insensitive to changes in the intensity of a stimulus, while retaining a high sensitivity to changes in stimulus intensity at the low end of the intensity scale. This logarithmic relationship, which is known as Fechner's Law, was used to develop the scale of loudness called the decibel scale.
Equal increments along the decibel scale reflect equal increments in loudness, as humans perceive it, and not equal increments in the intensity of the physical stimulus, the sound wave.The lowest stimulus intensity required for detection is the absolute threshold, whereas the smallest noticeable difference between a standard stimulus intensity and another stimulus value is the difference threshold.
Sensation: Color and Absolute Threshold Correct Essay presented is called the _____. a) absolute threshold Correct. The point at which a person can detect a stimulus 50 percent of the time it is presented is called the absolute threshold.
b) range threshold c) difference threshold. The absolute threshold is defined as the minimum amount of stimulation necessary for a stimulus to be detected 75 percent of the time. D) The absolute threshold is defined as the minimum amount of stimulation necessary for a stimulus to be detected 60 percent of the time.
Absolute threshold - The absolute threshold is the point where something becomes noticeable to our senses. It is the softest sound we can hear or the slightest touch we can feel. Anything less than this goes unnoticed.
Sensation is the process by which we detect stimulus energy from our environment and transmit it The correct answers to Handout 6–1 are as follows: 1. F 2. T 3. F 4. F 5. T 6. T 7. T 8. T 9. T Gustav Fechner identified an absolute threshold as the minimum stimulation needed to detect a particular stimulus 50 percent of the time.
–Contrast sensation and perception, and explain the difference between bottom-up processing you to use the absolute threshold for sensation? A. telling the difference between sweet and salty (color): dimension of color determined by wavelength of light.