The study engaged four different experimental groups: (1) control rats (C), which were exposed to the context but did not receive electrical stimulation; (2) rats exposed to the context unpaired with electrical stimulation (US); (3) trained rats (T5 and T29), which were exposed to the context paired with electrical stimulation, and (4) reexposed rats, which after exposure to the context paired with electrical stimulation, were reexposed 24 h later to the context without the aversive stimulus
for 3 min (R3), 15 min (R15), or 30 min (R30).
Even though we posit that Lymnaea perceives fear with the presentation of the CS after one-trial CTA training, we cannot dismiss the possibility that the snails simply detect an aversive stimulus
and respond appropriately, with no fear involved.
This stimulus is traditionally called aversive stimulus
or Unconditioned Stimulus (US) .
These results appear consistent with Michael's (2000) analysis of how the function of demands may be altered from an aversive stimulus
to an opportunity for the delivery of reinforcement.
Even a very mild aversive stimulus
could have a major impact on a person with high sensitivity to punishment.
Another way in which humans may learn to fear stimuli without direct experience of a physically aversive stimulus
, such as shock, is through the facial expressions of other individuals (e.g., Olsson & Phelps, 2004, 2007).
In a subsequent work (Huertas-Rodriguez, 1985), it was found that the probability of response with the CS+ word in the presence of the aversive stimulus
was greater when the aversive and neutral character of the stimuli were not crossed during the recall phase, that is, when the shock remained aversive and the tone was neutral.
A camera was placed above the tank to monitor the movements of the zebrafish, and statistical tests were performed to calculate whether the robot acted as an attractive, neutral or aversive stimulus
and whether this relationship depends on the fish being isolated or in a shoal.
For example, if a mother gently slaps (aversive stimulus
) her young son's hand as he reaches out to grab something his mother doesn't want him to touch, the child will withdraw his hand.
The lizard, which displayed a random series of social communicative signals, became an aversive stimulus
. The response to the archive footage of lizard displays was to produce a submissive display (i.e., head-bobbing or slow arm wave) or hyperactivity in which the subject makes an attempt to seek refuge.
Many people subjectively evaluate such a contingent procedure as "aversive." Therefore, people assume that manual restraint functions as a positive punisher in its ability (in a given case) to act as an aversive stimulus
Forgiveness is the reduction of conditioned aversive stimulus
or threat after a response has been made." (pp.