Reinforcement duration and the peak shift in post-discrimination gradients

Pigeons were trained to key-peck for food, first with single-stimulus training and then with successive discrimination (multiple schedule) training. In the multiple schedule, two different wavelengths were each correlated with equally frequent variable-interval reinforcement but different durations (6 sec vs. 2 sec) of access to grain. For some birds, the different durations of feeding cycle were cued by different intensities of the food hopper light. For some of these “cued” birds, single-stimulus training had been carried out with 6-sec feedings and when multiple-schedule training was introduced, the novel stimulus was correlated with 2-sec feedings. For the others, 2-sec feedings were originally used, and the novel stimulus was then present during the 6-sec reinforcement duration. The cueing procedure enhanced discrimination performance, and was necessary for the consistent production of a peak shift. In addition, the condition in which original training had been carried out with 6-sec feedings, and thus reinforcement duration was reduced in the presence of the novel stimulus, led to the best performance.     

Syntactic structure modifies attention during speech perception and recognition

The present paper demonstrates the interaction of syntactic structure and speech perception with a response task which minimizes the effects of memory: reaction time (RT) to clicks during sentences. (1) In 12-word unfamiliar sentences each with two clauses, RT is relatively slow overall to clicks located at the end of the first clause but decreases as a function of clause length. Clicks at the beginning of the second clause are not affected by length of the preceding clause. (2) In familiar sentences, RT is relatively fast to clicks located at the end of a clause while RT to clicks at the beginning of clauses is relatively unaffected by familiarity. (3) RT is not fastest overall to clicks located between clauses either in novel or familiar sentences. (4) As in previous studies, the subject's subsequent judegment of the location of the click tone are towards the clause break. (5) We could find no systematic interaction between RT and subjective click location. Findings (1) to (3) are consistent with the view that perceptual processing alternates between attending to all external stimuli and developing an internal representation of the stimuli. Finding (3) is in conflict with an “information channel” view of immediate attention to speech, which would predict high sensory attention to non-speech stimuli between clauses. However, findings (4) and (5) indicate that the channel view of perception may be correct for that perceptual processing which occurs after the immediate organization of the speech stimulus into major segments.     

Similarity of cardiac CR forms in the rhesus monkey during several experimental procedures

Cardiac rates of rhesus monkeys were observed in a variety of different conditioning procedures, each of which involved a visual stimulus (CS) followed by an electric shock (US). With a 30-sec CS, cardiac rate accelerated rapidly after CS onset, reached a maximum in the middle of CS, and decelerated thereafter, with a terminal CS rate often at the level of, or below, pre-CS levels. A similar biphasic cardiac rate response in CS was also observed under subsequent exposure to intermittent pairings of CS and US, avoidance of US, response-produced termination of US, and when CS-US pairings were superimposed upon an avoidance baseline, even when CS duration was varied from 12 to 60 seconds. The unusual regularity of cardiac rate responses in several different procedures may result from one or more of these factors: (a) characteristics of the rhesus monkey, (b) initial exposure to Pavlovian conditioning, or (c) the uniformity of measurement of cardiac rate employed in this study.     

Size and distance judgments under reduced conditions of viewing

Magnitude estimations of the size and distance of a variable relative to a standard were obtained in the absence of distance cues. Estimates were provided by different groups under three conditions: (a) physical size and distance variant, visual angle of the variable constant and equal to the standard, (b) physical size constant, physical distance and visual angle of variable changing, and (c) physical distance constant, physical size and visual angle of the variable changing. The results in both experiments were very similar. In each case both size and distance estimates conformed to relative visual angle. The results are applied to an analysis of size-matches that are obtained when distance cues are eliminated.     

The character in the hole experiment: Interaction of forward and backward masking of alphabetic character recognition by dynamic visual noise (OVN)

In the present study we consider the question of interaction between the forward and backward masking effects of dynamic visual noise (DVN) on the recognition of alphabetic characters composed of the same type of dots as those composing the DVN. The results of our experiments indicate that the two effects strongly interact so that both the duration and magnitude of the combined effect is far greater than would have been predicted by an algehraic model. Speculations about possible explanatory assumptions are presented.     

Persistent behavior maintained by unavoidable shocks

Squirrel monkeys were trained on a multiple schedule in which 10-min periods on a continuous shock avoidance schedule, indicated by a yellow light, alternated with 10-min periods on a 1.5-min variable interval schedule of food reinforcement (VI 1.5). A white light indicated that VI 1.5 was in effect, except for the middle 2 min of the period on VI 1.5, in which a blue light appeared and terminated with the delivery of a 0.5-sec unavoidable shock. Stable response rates developed in the avoidance and VI 1.5 components. However, the highest response rates occurred in the blue, preshock stimulus. A series of experiments showed that responding in the blue stimulus persisted even when responding had been extinguished on both the VI schedule of food reinforcement and the shock avoidance schedule. Responding in the blue stimulus ceased when the blue stimulus terminated without shock or when it terminated with a response-contingent shock. Each time responding ceased, it was restored by terminating the blue stimulus with an unavoidable shock. When the blue stimulus was on throughout each session and unavoidable shocks were delivered at regular 10-min intervals, responding was well maintained. These results show that in monkeys that have been trained on a continuous avoidance schedule, unavoidable shocks can maintain responding even under conditions where responses have no programmed consequences.     

Effects of increment size and reinforcer volume on progressive ratio performance

The progressive ratio schedule requires the subject to emit an increasing number of responses for each successive reinforcement. Eventually, the response requirement becomes so large that the subject fails to respond for a period of 15 min and thereby terminates the session. This point is arbitrarily defined as the “breaking point” of the subject's performance. The measure is quantified in terms of the number of responses in the final completed (i.e., reinforced) ratio run of the session. Previous work has shown that this measure varies as a function of several motivational variables and may thus be useful as an index of reinforcement strength. The present study is an extension of that work. The subjects were four rats. In the first experiment, the effects of the size of the increment by which each ratio run increased were studied. In two additional experiments, the volume of a liquid reinforcer was varied using both large and small ratio increments. The results indicate that the number of responses in the final completed ratio run increases as a function of the size of the ratio increment. However, the number of reinforcements obtained by the animals per session declines sharply. When large ratio increments are used, the number of responses in the final ratio increases as a function of the volume of the reinforcer, but when small increments are used, progressive satiation results in a decline in performance with the larger volumes of liquid.     

Effects of an Accelerated Reading Course on SAT-V Scores

3 groups of university freshmen took the SAT-V before and after a course in Accelerated Reading. The mean post-test scores for 2 groups increased slightly less than 10 points, while the mean post-test score for the third group decreased significantly. It is concluded that for the type of students used in this study, a course emphasizing speed and accuracy of reading is not of value in increasing scores on the verbal part of the Scholastic Aptitude Test.