Psychometric function

Psychometric function

A psychometric function describes the relationship between a parameter of a physical stimulus and the responses of a person who has to decide about a certain aspect of that stimulus. The psychometric function usually resembles a sigmoid function with the percentage of correct responses (or a similar value) displayed on the y-axis and the physical parameter on the x-axis. If the stimulus parameter is very far towards one end of its possible range, the person will always be able to respond correctly. Towards the other end of the range, the person never perceives the stimulus properly and therefore the probability of correct responses is at chance level. In between, there is a transition range where the subject has an above-chance rate of correct responses, but does not always respond correctly. The inflection point of the sigmoid function or the point at which the function reaches the middle between the chance level and 100% is usually taken as sensory threshold.

A common example is visual acuity testing with an eye chart. The person sees symbols of different sizes (the size is the relevant physical stimulus parameter) and has to decide which symbol it is. Usually, there is one line on the chart where a subject can identify some, but not all, symbols. This is equal to the transition range of the psychometric function and the sensory threshold corresponds to visual acuity. (Strictly speaking, a typical optometric measurement does not exactly yield the sensory threshold due to biases in the standard procedure.)

ee also

* Psychophysics
* Psychometrics


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Psychometric software — is software that is used for psychometric analysis of data from tests, questionnaires, or inventories reflecting latent psychoeducational variables. While some psychometric analyses can be performed with standard statistical software like SPSS,… …   Wikipedia

  • Psychometric Entrance Test — The Psychometric Entrance Test (PET, colloquially known in Hebrew as the Psychometry ha Psixometri , הפסיכומטרי) is a standardized test in Israel, generally taken as a higher education admission exam. The PET covers three areas: quantitative… …   Wikipedia

  • Cognitive Function Scanner — The Cognitive Function Scanner (CFS) [1][2] originally developed by Peter Laursen, DMedSci, DPsySci, and Thomas Sams, PhD, for the Danish National Institute of Occupational Health in the early 1980s. It is a computer aided cognitive assessment… …   Wikipedia

  • Psychophysics — is a subdiscipline of psychology dealing with the relationship between physical stimuli and their subjective correlates, or percepts. Psychophysics has been described variously as “the scientific study of the relation between stimulus and… …   Wikipedia

  • Absolute threshold of hearing — The absolute threshold of hearing (ATH) is the minimum sound level of a pure tone that an average ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the… …   Wikipedia

  • психометрическая кривая — 3.1.19 психометрическая кривая (psychometric function): Функция, выражающая зависимость доли (или процента) положительных ответов субъектов на предъявленные стимулы от физических параметров стимула. Источник …   Словарь-справочник терминов нормативно-технической документации

  • Just noticeable difference — In psychophysics, a just noticeable difference, customarily abbreviated with lowercase letters as jnd, is the smallest difference in a specified modality of sensory input that is detectable by a human being. It is also known as the difference… …   Wikipedia

  • Scale (social sciences) — In the social sciences, scaling is the process of measuring or ordering entities with respect to quantitative attributes or traits. For example, a scaling technique might involve estimating individuals levels of extraversion, or the perceived… …   Wikipedia

  • Eye chart — NOTOC Infobox Laboratory equipment name = Eye chart caption = Typical Snellen chart used for visual acuity testing. acronym = other names = uses = Vision testing inventor = manufacturer = model = related = Snellen chart Landolt C Lea test Tibetan …   Wikipedia

  • Detection theory — Detection theory, or signal detection theory, is a means to quantify the ability to discern between signal and noise. According to the theory, there are a number of determiners of how a detecting system will detect a signal, and where its… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”