Variable ratio reinforcement

There are many variants in drug discrimination methodology whereby small procedural differences (fixed or variable interval instead of fixed or variable ratio reinforcement, probe trials with or without... 

There are two conditions that have to be satisfied if punishment is to be effective - the behaviour is punished immediately after it occurs, and the behaviour is punished every time it occurs. In other words, if you want to use punishment as a way of influencing behaviour, you have to be in a position to catch every infringement and punish it immediately. If you wanted to use punishment, by itself, to get people to wear ear defenders, for example, you would have to have a manager watching every worker all the time they were at work and be ready to issue some form of punishment, even just a rebuke, every time they failed to put on their ear defenders in a noisy environment. Contrast this with the much easier requirement for keeping the behaviour (even undesirable behaviour) going, for example, variable ratio reinforcement ... 

Within the work situation in general, praise is used far less effectively than it might be. Variable ratio reinforcement suggests that praise should not be used on every occasion, indeed, if over-used it will eventually lose some of its value. This being said, the evidence is that it is hardly used at all. Why is this A survey amongst managers suggested a number of reasons. Some took the view that it was inappropriate - their employees were already... 

One approach is to find a means to reinforce the desired behaviour, preferably on a variable ratio schedule. One such example was reported from a factory in Liverpool (see Chapter 3). The introduction of a prize draw, based upon tokens collected for attendance, led to the reduction of absenteeism levels to almost zero. Other schemes have used cash bonuses for those attending on days chosen at random during the month. Both of these types of schemes use variable ratio reinforcement - one by means of a draw, the other by the random choice of the day on which attendance is rewarded. (It is worth noting that both also required attendance at the required starting time, thus also reinforcing punctuality.)... 

There are four simple schedules of reinforcement the fixed interval (FI) and the variable interval (VI), both of which are temporally based reinforcement schedules, and the fixed ratio (FR) and the variable ratio... 

Figure 9 Schematic cumulative records of performance on the fixed ratio (FR), variable ratio (VR), fixed interval (FI), and variable interval (VI) schedules of reinforcement. Responses are cumulated vertically over time. Each downward deflection of the pen represents reinforcement delivery horizontal lines indicate pausing. (Reproduced from Seiden LS and Dykstra LA (1977) Psychopharmacology A Biochemical and Behavioral Approach. New York, NY Van Nostrand Reinhold.)...

Variable ratio schedule delivers reinforcement after a changing number of responses... 

As well as fixed and variable ratios, there can also be fixed and variable times. The effects are similar - fixed time reinforcement is a relatively ineffective way of maintaining behaviour. It remains, of course, the most common way of paying salaries, which is why regular salaries are not an effective way of influencing behaviour.)... 

Xi Z.X., Gilbert J.G., Pak A.C., Ashby C.R., Jr., Heidbreder C.A., Gardner E.L. Selective dopamine D3 receptor antagonism by SB-277011 A attenuates cocaine reinforcement as assessed by progressive-ratio and variable-cost-variable-payoff fixed-ratio cocaine self-administration in rats. Eur. J. Neurosci. 21 3427, 2005. 

Reinforced plastics are usually applied as laminates of several layers. Many variables are important in determining the performance of the finished product. Some of the important ones are orientation of plies of the laminate, type of resin, fiber-resin ratio, type or types of fibers, and orientation of fibers. 

In the habit modality, response is mainly controlled by stimuli that precede rather than follow it (outcomes) (Dickinson, 1994). As a result of this, devaluation of response outcome fails to impair habit responding. Habit responding takes place as a result of exhaustive training on high ratio schedules or under variable interval schedules where reinforcement is loosely related to response (Dickinson, 1994). 

With both the PEA/P(S-co-MMA) and PB/PS IPN s, an important variable is the ratio of elastomer to plastic in the final material. When the plastic component predominates, a type of impact-resistant plastic results. In this manner the PB/PS IPN s are analogous to the impact-resistant graft copolymers. When the elastomer component predominates, a self-reinforced elastomer results, the behavior resembling that of the ABA-type block copolymers (thermoplastic elastomers) described in Section 4.4. When the overall compositions of both the PB/PS and the PEA/P(S-co-MMA) series are close to 50/50, the materials behave like leathers. 

Quantitative predictions of the effects of fillers on the properties of the final product are difficult to make, considering that they also depend on the method of manufacture, which controls the dispersion and orientation of the filler and its distribution in the final part. Short-fiber- and flake-filled thermoplastics are usually anisotropic products with variable aspect ratio distribution and orientation varying across the thickness of a molded part. The situation becomes more complex if one considers anisotropy, not only in the macroscopic composite but also in the matrix (as a result of molecular orientation) and in the filler itself (e.g., graphite and aramid fibers and mica fiakes have directional properties). Thus, thermoplastic composites are not always amenable to rigorous analytical treatments, in contrast to continuous thermoset composites, which usually have controlled macrostructures and reinforcement orientation [8, 17]. 

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