Stimuli


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Stimuli

 

in biology, various alterations in the external or internal environment of an organism that are capable, when acting on a biological system such as nervous, muscular, or glandular tissue, of altering the system’s original state, that is, of producing excitation. Stimuli may be physical, chemical, and physicochemical and adequate or inadequate. They affect specific nerve endings (receptors) and other cells of organs and tissues.

References in periodicals archive ?
It has been suggested that the N400, the peak of which will decrease when related stimulus pairs are presented and increase when unrelated stimulus pairs are presented, reflects the strength of the connection between stimuli, which is dependent on the participants' learning history (Ortu, 2012; Ortu, Allan, & Donaldson, 2013).
Thus, two configurations can be used to test results: (1) A Type 2 probe without mask consisting of an undefined novel sample stimulus and comparison stimuli (defined, undefined from the exclusion probe, and novel undefined stimuli), with the correct response being the novel undefined stimulus; (2) A Type 4 probe without mask consisting of an undefined sample stimulus from the exclusion probe and comparison stimuli (defined, undefined from the exclusion probe and novel undefined stimulus), with the correct response being the undefined stimulus from the exclusion probe.
The stimuli were presented in a random sequence of 270 trials in 30 blocks.
The stimuli, called A, A", B and B', were four figures constructed from Lego[R] game pieces that were easily assembled (2 cubes: 3,2 cm L x 3,2 cm W x 5 or 5,2 H; and two pyramids: 6,4 cm L x 6,4 cm W x 5,2 or 5,4 cm H, see Figure 1).
This study utilised a retrospective analysis to assess the validity of TMS mapping protocols involving varying numbers of stimuli per cranial site.
Sosa (2014) recently has reviewed those kinds of procedures and their corresponding critiques regarding the demonstration of the conditioned reinforcement value by arbitrary stimuli. From our perspective, and omitting such critiques, the most pertinent comparison procedure seems to be chained schedules of reinforcement (Ferster & Skinner, 1957).
The authors reported that four children learned all the relations taught, showed the emergence of relations between the non-taught visual stimuli sets (BC, CB, DB, CD and DC) and the reading of the B, C and D sets.
However, some authors have argued that a simple discrimination procedure with a successive presentation of stimuli increases the probability of establishing a discriminated response that is controlled by aspects of the S+ and concurrently by aspects of the S- (Campos, Debert, Barros, & Mcllvane, 2011; Debert, 2003; Debert, Matos, & Mcllvane, 2007), which might not be the case in procedures with a simultaneous presentation of the stimuli.
After presenting students with all possible pairs of stimuli, educators determine preferences based on the proportion of times an item was selected from all presentations.
Visual stimuli were generated using PsychToobox software (Brainard, 1997; Pelli, 1997) on a Macintosh computer and projected onto a rear screen, located 32 cm from the participant's eyes by a projector (PG-B10S; SHARP, Osaka, Japan) via a mirror.
The training was carried out using two pairs of stimuli: 1 and 3; 4 and 6.
The data collected shows that psychiatrically healthy carriers of the TCF4 gene also filter stimuli less effectively - like people who suffer from schizophrenia.