Stimulus response learning

Stimulus-response learning in passive avoidance test —... 

This section deals with the psychological principles of learning. A number of authors have classified learning processes into a hierarchy of levels, building from the simplest stimulus response learning to the most complex processes of research and problem solving. Three levels of learning are particularly relevant ... 

Instrumental learning is formally defined as the learning of a stimulus-response contingency. As a result of this learning, the organism emits responses contingent upon the stimulus. 

In principle it might be a Pavlovian habit related to the establishement of a direct association between a Pavlovian CS and an UR (see Cardinal et ah, 2004). Another possibility is that automatic responding is an instrumental habit related to learning of an instrumental stimulus-response (S-R) association. An instrumental habit is more likely to account for the relative flexibility of the behavior as indicated by the ability to rapidly switch to an explicit goal-oriented mode when the automatic responding is impaired. 

To increase efficiency, many companies adopted the learning theory s stimulus/response model of behavior modification, where the employees who worked the fastest and produced the most results were rewarded with raises, promotions, or other positive reinforcers [3]. This relates to our discussion on rewards and doing a job faster to keep being rewarded. 

The deviation of a real reactor from ideal systems is deduced by a widely used method of inquiry, the stimulus-response experiment with a nonreactive tracer. The goal is not knowledge of all the hydrodynamic details of the real flow, but to know how long the molecules stay in the reactor or, more precisely, determination of the residence time distribution (RTD). Based on the RTD and a respective link to the mass balance and conversion equation, respectively, the conversion of a reactant in a real reactor can then be calculatecL We will learn this in Sections 4.10.5.2 and 4.10.6.2, limiting ourselves to the case of single-phase flow and steady-state operation. 

What can be learned about the stimulus-response pathways from the evidences gathered in the last sections. ... 

What can be learned from the findings in these patients about the normal and abnormal structure of stimulus-response pathways ... 

The top half of Figure 7.4 depicts the sequence of stimulus-response events occurring in classical conditioning. Actually, before learning occurs, the sequence includes only three events—conditioned stimulus (CS), unconditioned stimulus (UCS), and unconditioned response (UCR). The UCS elicits a UCR automatically, as in an autonomic reflex. That is, the food (UCS) elicited a salivation reflex (UCR) in Pavlov s dogs. In the same way, the smell of popcorn (UCS) might make your mouth water (UCR), a puff of air to your eye... 

Mechanism through which repeated associations between two stimuli induce a new learned response. In particular, by pairing a neutral stimulus (conditioned stimulus) with an unconditioned stimulus (that induces a physiological response) many times, the neutral stimulus alone will be capable of producing a conditioned physiological response. 

The acquired or conditioned salivary reflex is elicited in response to the thought, sight, smell, or sound of food. As demonstrated with Pavlov s dog, these stimuli result in a learned response. Another stimulus that enhances salivation is nausea. Salivary secretion is inhibited by fatigue, sleep, fear, and dehydration. Overall, 1 to 2 1 of saliva may be produced per day. 

In addition, stimulus-control and cue-exposure techniques (see Chapter 5) can be used effectively as relapse prevention strategies. Stimulus control means that the client learns how to control her or his level of exposure, and under what conditions, to a particular cue that had been associated with drug use. Cue exposure, as you may remember, uses exposure and response-prevention strategies in session to reduce the power of a drug-use cue to trigger cravings or urges to use. 

F%. 1 (a) Dose-response curve from rats trained to discriminate between 0.2 mg kg of nicotine and saline. Data are from 13 rats, each tested at least three times at each dose, (b) Block of nicotine (0.2 mg kg ) discrimination by the centrally active nicotinic antagonist mecamylamine (0.25 mg kg ) but not by chlorisondamine at a 0.025 mg kg dose that blocks peripheral nicotinic choUnoceptors but does not penetrate into the CNS (Sal, Saline Nic, Nicotine Csd, Chlorisondamine Mec, Mecamylamine). Chlorisondamine blocks nicotine discrimination when injected intra-cerebroventricularly (Kumar et al. 1987, data not shown). Data shown are for the number of sessions that began with selection of the nicotine-appropriate lever expressed as a percentage of the total number of sessions. Redrawn with permission from Tables 1 and 2 in Morrison CF, Stephenson JA. Nicotine injections as the conditioned stimulus in discrimination learning (1969), Copyright Springer... 

Fig. 1 Active choice of intravenous nicotine in experimentally naive squirrel monkeys, a Monkeys sat in chambers equipped with two levers and distinctly colored light stimuli above the levers. Completion of the response requirement (the ratio) on the active lever produced a brief 2-s presentation of a light stimulus and an intravenous injection of nicotine followed by a timeout (TO) period of 5-60 s. Completion of the ratio requirement on the inactive lever resulted in presentation of a brief 2-s light stimulus of a different color but no injection. The fixed-ratio (FR) response requirement was gradually increased over successive sessions from one to ten (FR 1-FR 10). b Mean percentage choice for responding on the active lever by monkeys when they were experimentally naive (first week under a FR 1 schedule) and when they had learned to self-administer nicotine under the FR 10, TO 60s schedule (first week under the FR 10 schedule). P < 0.01, compared to the first week of training. From Le FoU et al. (2007b)...

Einally, classical conditioning is pretty well known from Pavlov s famous studies of dogs many years ago. Pavlov demonstrated that when dogs were conditioned to associate an unpleasant stimulus with one that would usually elicit no response, they learn to react to the latter response. Thus, if the sound of a bell is quickly followed by an electric shock, and this is repeated a number of times, the dogs will learn to react (yelp, say) to the sound of the bell alone. The dogs have been conditioned to associate the sound of the bell with an unpleasant experience. 

Conditioning a type of learning in which an unpleasant stimulus becomes associated with one that would ordinarily elicit no response. 

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