Blocking of the response-reinforcer association: Additional evidence

Response rates maintained by free-operant schedules are sometimes reduced when a brief signal is interposed between the response and reinforcer. Early interpretations of this rate reduction were in terms of associative competition between the response and signal, analogous to blocking and overshadowing effects obtained in Pavlovian conditioning. But subsequent evidence has disputed this interpretation by showing that the signal enhances response rate in several circumstances. The present study attempted to define the conditions determining the different effects by investigating the role of signal location in the delay-of-reinforcement interval. When it occurred immediately after a response, response rate was enhanced. When it occurred at the end of the delay interval, immediately preceding the reinforcer, the signal decreased response rate. A similar decremental effect occurred when the signal occurred in the middle of the delay interval, contiguous with neither the response nor the reinforcer. Similar blocking effects occurred with a response acquisition procedure. The results demonstrate that blocking effects do indeed occur in instrumental conditioning but that the usual procedure of using signals immediately contingent on responding confounds such blocking effects with the competing effects of conditioned reinforcement/marking.     

Associative interaction: joint control of key pecking by stimulus-reinforcer and response-reinforcer relationships

The joint control of rate of key pecking in pigeons by stimulus-reinforcer and response-reinforcer relationships was studied in the context of a two-component multiple schedule of reinforcement. Food presentation was always associated with one component and extinction with the other. The stimulus-reinforcer relationship was manipulated by varying the relative durations of the two components. In the food-presentation component, a fixed rate of reinforcement, independent of rate of responding, was generated by a schedule referred to as “T*”. One aspect of the response-reinforcer relationship, contiguity, was manipulated by varying the percentage of delayed reinforcers. With the multiple T* extinction schedule, stimulus-reinforcer and response-reinforcer relationships could be varied independently of one another. Rate of key pecking was sensitive to manipulations of both relationships. However, significant differential effects due to either the stimulus-reinforcer or response-reinforcer relationship were obtained only when the other relationship was weak: stimulus-reinforcer and response-reinforcer relationships interacted in the joint control of responding.     

Associative blocking of the mccollough effect

After exposure to two simultaneously presented achromatic grids (A and B) on a coloured field, subjects reported colour aftereffects on each of the separately presented grids. These aftereffects were shown to be examples of the McCollough effect, since they were contingent upon the subjects having experienced the grid in combination with the coloured field. Exposure to the coloured field in advance of combining the colour field with the grids attenuated the strengths of the aftereffects on the A and B grids. Moreover, exposure to the A grid on the coloured field in advance of combining the B grid with the A grid on the coloured field abolished the aftereffect on the B grid. The failure of the B grid to arouse the aftereffect was due to the presence of the already trained A grid, since exposure to the A grid on the coloured field followed by exposure to the B grid on that field yielded the aftereffect on the B grid. The conditions under which the McCollough effect was attenuated are those under which learning fails to occur in Pavlovian conditioning procedures. The results, therefore, supported the view that the pairing between the grids and the colour resulted in a learned association between the grids and some aspect of the response by the visual system to the colour.     

Sniffy,the virtual rat: Simulated operant conditioning

We report on the use of our Sniffy program to teach operant conditioning to 900 introductory psychology students. The simulation is designed primarily to teach the principles of shaping and partial reinforcement in an operant chamber. Advanced features are provided for exploring modeling issues and the learning parameters of the model. Students observe the rat’s pretraining behaviors, shape barpressing, and explore the effects of partial reinforcement schedules on a cumulative record. Any of 30 actions can be trained to occur in specific locations in the Skinner box. This paper summarizes details about the software, interface, and instructional objectives.     

Procedure for operant conditioning of the dog

Most reports arising from operant conditioning procedures have little or no emphasis on the actual behavior shaping or acquisition phase of the responses which are the cumulative frequency of the well-practiced act. There is a need for more detail for beginners or those desiring a clearer understanding of procedures leading to the finally reported data. The procedure reported here is typically used to compare animal subjects or conditions, such as drugs, both in the acquisition and final phases of behavior. Beginning with an unconditional response (e.g. feeding) a bridging stimulus is paired in classical conditioning fashion. From that point on the bridging stimulus and UCS (feeding—or shock) are used immediately as reward or reinforcement only for responses “in the direction of the final desired behavior. The number of timed standardized behavior shaping sessions to criterion is the best index of acquisition phase performance and the total number bar presses or the rate of bar pressing (slope) is the usual index of operant responding. With timid animals it is often necessary to administer tranquilizers.     

Effects of operant conditioning on the GSR

Each of nine Ss was run for 11 daily sessions. Except for the first (operant level) and last two (extinction) sessions, 500-ohm drops in skin resistance were followed by reinforcement (light). These reinforcement periods lasted 20 min and were preceded by 10-min control periods during which no reinforcement was administered. Although the results showed no evidence for operant conditioning of the GSR, they did indicate that increased emission of GSR's occurred during the reinforcement period. This effect was shown to hold for Ss with low operant levels of GSR's but not for Ss with high operant levels.     

Irrelevant incentive learning during instrumental conditioning: The role of the drive-reinforcer and response-reinforcer relationships

Four experiments investigated the processes by which a motivationally-induced change in the value of the training reinforcer affects instrumental performance. Initially, thirsty rats were trained to lever press for either a sodium or non-sodium solution. In Experiment I sodium-trained rats responded faster in extinction following the induction of a sodium appetite, but not following either food or water deprivation. Thus, enhanced extinction performance depends upon the relevance of the training reinforcer to the test drive state. The remaining experiments examined the role of the instrumental contingency. Animals received response-contingent presentations of one solution alternated either within (Experiments II and III) or between sessions (Experiment IV) with non-contingent presentations of another solution. Neither procedure yielded convincing evidence that contingent sodium presentations generated more responding in extinction under a sodium appetite than did non-contingent sodium presentations. On the basis of these results, we argue that the instrumental contingency itself does not play a major role in this irrelevant incentive effect.     

Compound conditioning: Elimination of the blocking effect

Prior conditioning employing one element of a compound stimulus as the CS blocked the acquisition of a Conditioned Emotional Response (CER) to the second element of a simultaneous compound stimulus that was subsequently used as the CS in further conditioning trials. Presentation of a brief “surprise” stimulus 3 or 5 sec after the occurrence of the US during the compound trials eliminated the blocking effect.     

Sensorimotor EEG operant conditioning: Experimental and clinical effects

Neurophysiological studies in cats have established a functional relationship between waking 12–15 Hz sensorimotor cortex rhythmic EEG activity (the sensorimotor rhythm or SMR) and a similar pattern during sleep, the sleep spindle. Both result from oscillatory thalamocortical discharge involving ventrobasal thalamus and sensorimotor cortex, and both are associated with a state of suppressed motor excitability. Enhancement of the SMR with operant conditioning methods in the cat clearly led to reduced seizure susceptibility. The experimental application of this approach to seizure control in epileptics has resulted in (A) evidence that EEG patterns can be manipulated significantly in man with operant conditioning, (B) suggestive observations concerning a potential component of pathology in epilepsy, and (C) strong preliminary evidence that SMR operant conditioning in epileptics is specifically therapeutic. Current research has focused upon the EEG during sleep in epileptics with primary motor symptomatology. This measure often reveals several hard signs of pathology. These include the presence of abnormal activity in the 4–7 Hz frequency band and the absence or disturbance of activity in the 11–15 Hz frequency band. Power spectral analysis is being utilized to quantify these sleep EEG components in five groups of epileptic patients, studied with different frequency patterns rewarded in an A-B-A design which provides for counterbalancing of order effects. Initial laboratory training is followed by 9–12 months of training at home with portable feedback equipment. Reward contingencies are reversed within each group at approximately three month intervals. Clinical EEG data, blood anticonvulsant measures and patient seizure logs supplement sleep EEG data obtained before training and after each phase of the design. Early results have again indicated specific therapeutic benefits following training of high frequency rhythmic central cortical activity.     

Muscle tension in human operant heart rate conditioning

The physiological mechanism involved in human operant heart rate conditioning is not known. If skeletal muscle tension is a mediator, it should be possible to generate significant heart rate increases by inconspicuous voluntary muscle tension. Eleven subjects were instructed to generate inconspicuous muscle tension for 90-second periods. No gross muscle movements were observed, but average heart rate during the trials was over 13 beats-per-minute greater than pre-trial base lines. Respiratory pattern changes and surface electromyogram changes did not reliably correlate with heart rate increases. Inconspicuous muscle tension could be a mediator in human operant heart rate conditioning, and cannot be ruled out by absence of change in respiratory pattern or electromyogram.     

Extraversion and reinforcement in verbal operant conditioning.

The present investigation was designed to study the relationship between extraversion and modes of reinforcement in verbal operant conditioning. A 4 X 3 randomized block design was replicated ten times. Eighty graduate and post-graduate male students were individually subjected to the standard Taffel conditioning procedure. When the numbers of conditioned responses produced by introverts and extraverts were compared, it was found that: (1) under negative reinforcement ('bad' and electric shock), with both the female and male experimenters, and under positive reinforcement ('good') with the male experimenter, the introverts' score was the higher of the two; (2) under positive reinforcement ('good') with the female experimenter, the extraverts' score was higher than that of the introverts.     

Design decisions in a Pascal-based operant conditioning system

FREDL, a Pascal-based system for control of operant experiments, has been implemented on the IBM PC computer. In the foreground, recurring operations, such as decrementing counters that serve as local clocks, are controlled by a dictionary specifying automatic properties of user defined variables, and random logic is implemented by a user-written Pascal overlay. In the background, the remainder of the program controls communication with the user, output of data to disk, and production of cumulative records.     

Stimulus- and response-reinforcer contingencies in autoshaping, operant, classical, and omission training procedures in rats

Separate groups of rats received 500 trials of lever-press training under autoshaping (food delivery followed 10-second lever presentations, or occurred immediately following a response); operant conditioning (responding was necessary for food delivery); and classical conditioning (food followed lever presentations regardless of responding). Each group then received 500 trials on an omission procedure in which food was omitted on trials with a response. Another group received 1000 trials on the omission procedure, and a fifth group, random control, received 1000 uncorrelated presentations of lever and food. The autoshaping, operant, and classical groups reached high response levels by the end of initial training. Acquisition was fastest in the autoshaping group. Responding remained consistently low in the control group. The omission group responded at a level between the control group and the other three groups. During omission training, responding in these three groups declined to the omission-group level. During omission training, the rats continued contacting the lever frequently after lever pressing had declined. Response maintenance under omission training seems not to require topographic similarity between the response and reinforcer-elicited consummatory behaviors.     

Controlling pain reports through operant conditioning: a laboratory demonstration

Operant conditioning of pain reports was studied in two laboratory experiments. In the first one 5 subjects were given the same pain stimulus on 15 trials and their recorded pain ratings gave no systemic trends across subjects. 8 other subjects received the same pain tests but on some of the trials increases or decreases in pain ratings were verbally reinforced while the noxious stimulus was held constant across trials. Clear and significant differences between reinforced increases and decreases in pain reports were observed. In Exp. 2, 5 subjects were given neutral feedback and systematically decreasing levels of noxious stimulation, resulting in a good correlation between pain ratings and stimulation level. 5 subjects were provided reinforcement for increasing pain reports while the pain stimulus was systematically reduced. Increases in pain reports were observed simultaneously with large decreases in the level of the noxious stimulus. Results of these experiments support the operant conception of pain.