Contrast of hemispheric lateralization for oro-facial movements between learned attention-getting sounds and species-typical vocalizations in chimpanzees: Extension in a second colony

Studies involving oro-facial asymmetries in nonhuman primates have largely demonstrated a right hemispheric dominance for communicative signals and conveyance of emotional information. A recent study on chimpanzee reported the first evidence of significant left-hemispheric dominance when using attention-getting sounds and rightward bias for species-typical vocalizations (Losin, Russell, Freeman, Meguerditchian, Hopkins & Fitch, 2008). The current study sought to extend the findings from Losin et al. (2008) with additional oro-facial assessment in a new colony of chimpanzees. When combining the two populations, the results indicated a consistent leftward bias for attention-getting sounds and a right lateralization for species-typical vocalizations. Collectively, the results suggest that both voluntary-controlled oro-facial and gestural communication might share the same left-hemispheric specialization and might have coevolved into a single integrated system present in a common hominid ancestor.     

How cross-fostered chimpanzees (Pan troglodytes) initiate and maintain conversations

This study systematically sampled typical attention-getting sounds and sign language conversations between each of 4 originally cross-fostered chimpanzees (Pan troglodytes), still living freely, but now in a laboratory setting, and a familiar human interlocutor. Videotape records showed that when they encountered a human interlocutor sitting alone at his desk with his back turned to them, the cross-fosterlings either left the scene or made attention-getting sounds. The only signs they made to the interlocutor's back were noisy signs. When the human turned and faced them, the chimpanzees promptly signed to him (98% of the time) and rarely made any sounds during the ensuing signed conversations. Under systematic experimental conditions, the signed responses of the chimpanzees were appropriate to the conversational styles of the human interlocutor, confirming daily field observations.     

The infant vocal-conditioning literature: a theoretical and methodological critique

Most studies of operant conditioning of infant vocalization do not fully use the experimental-analysis-of-behavior methodology that behavioral researchers have developed to study operant phenomena. This could be a contributing factor in their failure to correctly operationalize the definition of reinforcement, severely limiting the amount of information they can provide about operant learning in infants. Furthermore, single-subject-design studies may be added to supplement or replace group experimental designs in the study of infant vocal conditioning if we are to recognize the different learning processes that affect infant learning. Finally, single-subject experimental designs may be crucial to the development of an effective technology of early language intervention.     

Olive baboons communicate intentionally by pointing

A pointing gesture creates a referential triangle that incorporates distant objects into the relationship between the signaller and the gesture’s recipient. Pointing was long assumed to be specific to our species. However, recent reports have shown that pointing emerges spontaneously in captive chimpanzees and can be learned by monkeys. Studies have demonstrated that both human children and great apes use manual gestures (e.g. pointing), and visual and vocal signals, to communicate intentionally about out-of-reach objects. Our study looked at how monkeys understand and use their learned pointing behaviour, asking whether it is a conditioned, reinforcement-dependent response or whether monkeys understand it to be a mechanism for manipulating the attention of a partner (e.g. a human). We tested nine baboons that had been trained to exhibit pointing, using operant conditioning. More specifically, we investigated their ability to communicate intentionally about the location of an unreachable food reward in three contexts that differed according to the human partner’s attentional state. In each context, we quantified the frequency of communicative behaviour (auditory and visual signals), including gestures and gaze alternations between the distal food and the human partner. We found that the baboons were able to modulate their manual and visual communicative signals as a function of the experimenter’s attentional state. These findings indicate that monkeys can intentionally produce pointing gestures and understand that a human recipient must be looking at the pointing gesture for them to perform their attention-directing actions. The referential and intentional nature of baboons’ communicative signalling is discussed.     

Evaluation of infant vocal conditioning.

The use of the operant conditioning paradigm, as it has been applied to infant social, vocal behavior, reflects a failure to take into account the social nature of human infants over and above the rigid theoretical rationale of the paradigm. It is argued that: (1) the baseline procedure used in operant conditioning studies is methodologically and conceptually invalid; (2) the reinforcing stimulus used in social conditioning studies elicits the very response that it is assigned to reinforce; and (3) the effect of the response-reinforcer relationship is not the reinforcement (strengthening) of vocal response rate.     

Speech perception by budgerigars(Melopsittacus undulatus): The voiced-voiceless distinction

Discrimination of synthetic speech sounds from the bilabial, alveolar,and velar voice onset time (VOT) series was studied in 5 budgerigars. The birds were trained, using operant conditioning procedures, to detect changes in a repeating background of sound consisting of a synthetic speech token. Response latencies for detection were measured and were used to construct similarity matrices. Multidimensional scaling procedures were then used to produce spatial maps of these speech sounds, in which perceptual similarity was represented by spatial proximity. The results of these experiments suggest that budgerigars discriminate among synthetic speech sounds from these three VOT continua, especially between those from the bilabial and alveolar series, in a categorical fashion.     

Operant conditioning in redwinged blackbirds

An operant conditioning technique for use with passerine birds is described. Two redwinged blackbirds were successfully conditioned to perch-hop for food reinforcement. Continuous reinforcement and fixed-ratio schedules involving substantial ratio requirements were used to maintain this response. The behavior of the two redwinged blackbirds was comparable to that of more conventional organisms working on similar schedules of reinforcement.     

The dynamics of operant conditioning

Existing models of operant learning are relatively insensitive to historical properties of behavior and applicable to only limited data sets. This article proposes a minimal set of principles based on short-term and long-term memory mechanisms that can explain the major static and dynamic properties of operant behavior in both single-choice and multiresponse situations. The critical features of the theory are as follows: (a) The key property of conditioning is assessment of the degree of association between responses and reinforcement and between stimuli and reinforcement; (b) the contingent reinforcement is represented by learning expectancy, which is the combined prediction of response-reinforcement and stimulus-reinforcement associations; (c) the operant response is controlled by the interplay between facilitatory and suppressive variables that integrate differences between expected (long-term) and experienced (short-term) events; and (d) very-long-term effects are encoded by a consolidated memory that is sensitive to the entire reinforcement history. The model predicts the major qualitative features of operant phenomena and then suggests an experimental test of theoretical predictions about the joint effects of reinforcement probability and amount of training on operant choice. We hypothesize that the set of elementary principles that we propose may help resolve the long-standing debate about the fundamental variables controlling operant conditioning.     

Operant techniques used in stuttering therapy: A review

This article reviews research concerning the use of operant conditioning in stuttering therapy, and discusses the clinical implications of this literature. In order to be considered for this review, a report had to treat the findings of research specifically designed to use operant conditioning in the manipulation of speech disfluency. This body of experimental literature clearly indicates that operant management techniques can effectively reduce stuttering with punishment of disfluencies producing more notable results than reinforcement of fluent responses. Operant conditioning is an effective means of modifying stuttering behavior and should be more visible in terms of procedures used by speech therapists.     

Introduction to The Special Issue on The Behavior Analysis and Treatment of Drug Addiction

Extensive evidence from the laboratory and the clinic suggests that drug addiction can be viewed as operant behavior and effectively treated through the application of principles of operant conditioning. Contingency management interventions that arrange for the direct reinforcement of drug abstinence or of other therapeutically important target behaviors (e.g., regular use of drug abuse treatment medications) are among the most studied type of operant treatments. Behavior analysts have contributed to the substantial and rapidly growing literature on operant treatments for drug addiction, but the publications of this work usually appear in medical, clinical psychology, or drug abuse journals. This special issue of the Journal of Applied Behavior Analysis represents an effort to bring this important work to the attention of the behavior-analytic community. The articles in this special issue illustrate both the enormous potential of contingency management interventions to address the serious and seemingly intractable problem of drug addiction as well as the real challenges involved in attempting to develop and disseminate treatments that will produce substantial and lasting changes in the lives of individuals plagued by the chronic problem of drug addiction.     

Schedule control of the vocal behavior of Cebus monkeys

The vocal behavior of three Cebus monkeys was maintained by fixed-ratio schedules of response dependent reinforcement at values between fixed-ratio 1 and fixed-ratio 15. In one monkey that was exposed to variable-interval, fixed-interval, and conjunctive fixed-ratio fixed-interval schedules of reinforcement, vocal responding occurred at a low rate, but schedule-appropriate patterns were maintained. The rates and patterns of responding engendered indicated that the vocal operant can be brought under schedule control in the monkey by the use of response-dependent reinforcement.     

Operant and nonoperant vocal responding in the mynah: Complex schedule control and deprivation-induced responding

Several recent studies have been concerned with operant responses that are also affected by nonoperant factors, (e.g., biological constraints, innate behavior patterns, respondent processes). The major reason for studying mynah vocal responding concerned the special relation of avian vocalizations to nonoperant emotional and reflexive systems. The research strategy was to evaluate operant and nonoperant control by comparing the schedule control obtained with the vocal response to that characteristic of the motor responses of other animals. We selected single, multiple, and chain schedules that ordinarily produce disparate response rates at predictable times. In multiple schedules with one component where vocal responding (“Awk”) was reinforced with food (fixed-ratio or fixed-interval schedule) and one where the absence of vocal responding was reinforced (differential reinforcement of other behavior), response rates never exceeded 15 responses per minute, but clear schedule differences developed in response rate and pause time. Nonoperant vocal responding was evident when responding endured across 50 extinction sessions at 25% to 40% of the rate during reinforcement. The “enduring extinction responding” was largely deprivation induced, because the operant-level of naive mynahs under food deprivation was comparable in magnitude, but without deprivation the operant level was much lower. Food deprivation can induce vocal responding, but the relatively precise schedule control indicated that operant contingencies predominate when they are introduced.     

The operant and the classical in conditioned orientation of Drosophila melanogaster at the flight simulator

Ever since learning and memory have been studied experimentally, the relationship between operant and classical conditioning has been controversial. Operant conditioning is any form of conditioning that essentially depends on the animal's behavior. It relies on operant behavior. A motor output is called operant if it controls a sensory variable. The Drosophila flight simulator, in which the relevant behavior is a single motor variable (yaw torque), fully separates the operant and classical components of a complex conditioning task. In this paradigm a tethered fly learns, operantly or classically, to prefer and avoid certain flight orientations in relation to the surrounding panorama. Yaw torque is recorded and, in the operant mode, controls the panorama. Using a yoked control, we show that classical pattern learning necessitates more extensive training than operant pattern learning. We compare in detail the microstructure of yaw torque after classical and operant training but find no evidence for acquired behavioral traits after operant conditioning that might explain this difference. We therefore conclude that the operant behavior has a facilitating effect on the classical training. In addition, we show that an operantly learned stimulus is successfully transferred from the behavior of the training to a different behavior. This result unequivocally demonstrates that during operant conditioning classical associations can be formed.     

Defining reinforcess — A problem in communication for consultation in behavior modification

This paper reviews the respondent (Hull-Spence) and operant (Skinnerian) conditioning definitions of reinforcers and reinforcement and demonstrates the need to keep the systems separate when consulting about behavior modification. The two systems are shown to lead to different modification procedures.One important distinction between the systems is whether a reinforcer is simply associated with a response (respondent) or whether it must follow the response (operant). A second important distinction is the definition of negative reinforcement. In respondent conditioning, negative reinforcement entails presenting an aversive stimulus in association with the response and results in a decrease in response rate. In operant conditioning, negative reinforcement entails the removal of an aversive stimulus following a correct response, which results in an increase in response rate.     

A vocal response time system for use with sentence verification tasks

A software system for the reliable detection of vocal response onset is described. The system was designed specifically for the measurement of vocal response times to speech stimuli presented aurally in a sound field in the presence of some background noise. The response time extraction method described here is robust to masking noise and extraneous sounds that may be included in the subject’s recorded response. In addition, the response words do not have to be limited to a small set because the system is able to differentiate the onset of any speech sounds, including low-energy fricatives. The method described here may be implemented with any computer sound system because it relies only on the sound conversion clock for timing accuracy and uses postprocessing of the signal after acquisition for response extraction. The response time extraction technique as currently implemented does not recognize subject’s responses but could be incorporated into an automatic speech recognition system.     

Identification of a reinforcement pathway necessary for operant conditioning of head waving in Aplysia californica

The marine mollusc Aplysia californica exhibits a wide range of nonassociative and associative forms of learning. Recently, we found that the learning repertoire of Aplysia includes operant conditioning (Cook & Carew, 1986, 1989b). The behavior we examined is a naturally occurring, side-to-side head-waving response used by Aplysia in seeking food, obtaining a foothold, and egg laying. Aplysia can be operantly conditioned to reduce head-waving to one side of their body if such a response results in exposure to bright uniform-field illumination, which the animals find aversive. An essential step toward achieving a mechanistic understanding of operant conditioning is to identify and characterize the reinforcement pathway used during the learning. Toward this end, we wished to determine which of the peripheral visual pathways in Aplysia are critical for performance of the operant task. Previous experiments indicated that photic input from the optic and rhinophore nerves functionally inhibited motor neurons that participate in the operant response (head-waving), while photic input from the oral veil nerves excited these same motor neurons (Cook & Carew, 1989c). These findings suggested the hypothesis that one or both of these pathways could play an important role in mediating reinforcement during training. To explore this possibility we operantly trained animals that had received chronic bilateral transections of either the optic and rhinophore nerves or the oral veil nerves C1-C3 (in conjunction with transection of the optic and rhinophore nerves). We found that operant conditioning was not disrupted by ablation of input from the eyes and rhinophores. By contrast, ablation of input from the oral veil (together with that from the eyes and rhinophores) abolished operant conditioning. Thus, the oral veil nerves play a critical modulatory role in operant conditioning of head-waving. This observation further suggested that photic input from the oral veil is conveyed to the CNS via the oral veil nerves. In a final experiment we confirmed that stimulation of the oral veil with light evokes increased afferent activity in the oral veil nerves C1-C2. These results support the idea that the oral veil nerves contain processes that are critical components of the reinforcement pathway for operant conditioning of head-waving.     

Vocal Imitations and the Identification of Sound Events

It is commonly observed that a speaker vocally imitates a sound that she or he intends to communicate to an interlocutor. We report on an experiment that examined the assumption that vocal imitations can effectively communicate a referent sound and that they do so by conveying the features necessary for the identification of the referent sound event. Participants were required to sort a set of vocal imitations of everyday sounds. The resulting clusters corresponded in most of the cases to the categories of the referent sound events, indicating that the imitations enabled the listeners to recover what was imitated. Furthermore, a binary decision tree analysis showed that a few characteristic acoustic features predicted the clusters. These features also predicted the classification of the referent sounds but did not generalize to the categorization of other sounds. This showed that, for the speaker, vocally imitating a sound consists of conveying the acoustic features important for recognition, within the constraints of human vocal production. As such vocal imitations prove to be a phenomenon potentially useful to study sound identification.     

Multimodal communication by captive chimpanzees (Pan troglodytes)

Many studies have shown that apes and monkeys are adept at cross-modal matching tasks requiring the subject to identify objects in one modality when information regarding those objects has been presented in a different modality. However, much less is known about non-human primates’ production of multimodal signaling in communicative contexts. Here, we present evidence from a study of 110 chimpanzees demonstrating that they select the modality of communication in accordance with variations in the attentional focus of a human interactant, which is consistent with previous research. In each trial, we presented desirable food to one of two chimpanzees, turning mid-way through the trial from facing one chimpanzee to facing the other chimpanzee, and documented their communicative displays, as the experimenter turned towards or away from the subjects. These chimpanzees varied their signals within a context-appropriate modality, displaying a range of different visual signals when a human experimenter was facing them and a range of different auditory or tactile (attention-getting) signals when the human was facing away from them; this finding extends previous research on multimodal signaling in this species. Thus, in the impoverished circumstances characteristic of captivity, complex signaling tactics are nevertheless exhibited by chimpanzees, suggesting continuity in intersubjective psychological processes in humans and apes.