Sense of Smell For odors, the absolute threshold involves the smallest concentration that a participant is able to smell An example of this would be to measure the smallest amount of perfume that a subject is able to smell in a large roo

The just noticeable difference (JND), also known as the difference threshold, is the minimum level of stimulation that a person can detect 50 percent of the time The just noticeable difference would be the smallest change in volume that a person could sense

: of or relating to psychophysics also : sharing mental and physical qualities psychophysical color perception

Psychophysical relates to the relationship between one’s internal (psychic) and external (physical) worlds Psychophysical may refer to: Psychophysics, the subdiscipline of psychology dealing with the relationship between physical stimuli and their subjective correlates

The term psychophysiology refers to research that links psychological and physiological processes For example, we study the effects of psychosocial stress on the physiological stress response, as measured by skin conductance, release of cortisol, and changes in blood pressure and heart rate

Gustav Theodor Fechner

Human nature is the sum total of our species identity, the mental, physical, and spiritual characteristics that make humans uniquely, well, human Since then, definitions have split between scholars considering the body as part of human nature and those who see it as primarily a container for what is essentially huma

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Although he was educated in biological science, Fechner turned to mathematics and physics He also developed experimental procedures, still useful in experimental psychology, for measuring sensations in relation to the physical magnitude of stimuli

(A threshold is the lowest point at which a particular stimulus will cause a response in an organism) In human eye: Measurement of the threshold An important means of measuring a sensation is to determine the threshold stimulus—ie, the minimum energy required to evoke the sensation

The ‘Threshold’ Theory It suggested that the development of two or more languages in a balanced bilingual person moves upward through three identifiable levels, crossing two distinct thresholds in between levels

Difference Threshold – minimum difference in intensity between two stimuli that one can detect Absolute Threshold – minimum intensity of a stimulus that one can detect 50% of the time

Weber’s Law, more simply stated, says that the size of the just noticeable difference (ie, delta I) is a constant proportion of the original stimulus value The Weber fraction equivalent for this difference threshold would be 01 (delta I/I = = 01)

Weber’s law, also called Weber-Fechner law, historically important psychological law quantifying the perception of change in a given stimulus The law states that the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus

When you first walk through the door, the delicious smell of garlic and tomatoes is almost overwhelming You sit down to wait for a table, and after a few minutes, the scents begin to dissipate until you barely notice them This is an example of what is known as sensory adaptatio

Adaptation is the evolutionary process where an organism becomes better suited to its habitat An example is the adaptation of horses’ teeth to grinding grass Grass is their usual food; it wears the teeth down, but horses’ teeth continue to grow during life

In short, there are three major classes of nociceptors in the skin: Aδ mechanosensitive nociceptors, Aδ mechanothermal nociceptors, and polymodal nociceptors, the latter being specifically associated with C fibers

When the stimulus changes, your attention is drawn back to it Sensory habituation allows us to filter out continuous, relatively unchanging stimuli so that they do not constantly occupy our attention