Behavioural processes
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Behavioural processes · Jul 2017
Unique prediction of cannabis use severity and behaviors by delay discounting and behavioral economic demand.
Few studies have simultaneously evaluated delay discounting and behavioral economic demand to determine their unique contribution to drug use. A recent study in cannabis users found that monetary delay discounting uniquely predicted cannabis dependence symptoms, whereas cannabis demand uniquely predicted use frequency. This study sought to replicate and extend this research by evaluating delay discounting and behavioral economic demand measures for multiple commodities and including a use quantity measure. ⋯ These effects remained significant after controlling for other delay discounting and demand measures. This research replicates previous outcomes relating delay discounting and demand with cannabis use and extends them by accounting for the contribution of multiple commodities. This research also demonstrates the ability of online crowdsourcing methods to complement traditional human laboratory techniques.
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Behavioural processes · Apr 2017
ReviewReinstatement after human feature-positive discrimination learning.
In two experiments, using an online conditioned suppression task, we investigated the possibility of reinstatement of extinguished feature-target compound presentations after sequential feature-positive discrimination training in humans. Furthermore, given a hierarchical account of Pavlovian modulation (e.g., Bonardi, 1998; Bonardi and Jennings, 2009), we predicted A-US reinstatement to be stronger than US-only reinstatement. In Experiment 1, participants learned a sequential feature-positive discrimination (X→A+|A-), which was subsequently extinguished (X→A-). ⋯ Subsequently, group A-US received reinforced presentations of A during a reinstatement phase while group Control received exposure to the context. Final testing of the novel X→B compound was hypothesized to show higher responding in group A-US than in group Control, but findings of this approach were limited due to acquired equivalence and/or perceptual factors causing a secondary extinction effect. We conclude to have obtained clear evidence in favour of reinstatement of differential responding after human Feature-Positive discrimination training and subsequent compound extinction, but no evidence in favour of A-US presentations being a stronger trigger for reinstatement than are US-only presentations.
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Behavioural processes · Nov 2016
Coding and quantification of a facial expression for pain in lambs.
Facial expressions are routinely used to assess pain in humans, particularly those who are non-verbal. Recently, there has been an interest in developing coding systems for facial grimacing in non-human animals, such as rodents, rabbits, horses and sheep. The aims of this preliminary study were to: 1. ⋯ Agreement among observers for LGS scores were fair overall (Experiment I: W=0.60; Experiment II: W=0.66). This preliminary study demonstrates changes in lamb facial expression associated with pain. The results of these experiments should be interpreted with caution due to low lamb numbers.
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Behavioural processes · Nov 2016
Cognitive bias in rats evoked by ultrasonic vocalizations suggests emotional contagion.
Emotional contagion occurs when an individual acquires the emotional state of another via social cues, and is an important component of empathy. Empathic responses seen in rodents are often explained by emotional contagion. Rats emit 50kHz ultrasonic vocalizations (USVs) in positive contexts, and emit 22kHz USVs in negative contexts. ⋯ An ambiguous cue with a frequency falling between the two stimuli tested whether rats interpreted it as positive or negative. Results showed that rats responded to ambiguous cues as positive when they heard the 50kHz USV (positive vocalizations) and negative when they heard the 22kHz USV (negative vocalizations). This suggests that conspecific USVs can evoke emotional contagion, both for positive and negative emotions, to change the affective states in receivers.
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Both the response-reinforcer and stimulus-reinforcer relation are important in discrimination learning; differential responding requires a minimum of two discriminably-different stimuli and two discriminably-different associated contingencies of reinforcement. When elapsed time is a discriminative stimulus for the likely availability of a reinforcer, choice over time may be modeled by an extension of the Davison and Nevin (1999) model that assumes that local choice strictly matches the effective local reinforcer ratio. The effective local reinforcer ratio may differ from the obtained local reinforcer ratio for two reasons: Because the animal inaccurately estimates times associated with obtained reinforcers, and thus incorrectly discriminates the stimulus-reinforcer relation across time; and because of error in discriminating the response-reinforcer relation. ⋯ The inclusion of a parameter reflecting error in discriminating the response-reinforcer relation enhanced the ability of each version of the model to describe data. The ability of this class of model to account for a range of data suggests that timing, like other conditional discriminations, is choice under the joint discriminative control of elapsed time and differential reinforcement. Understanding the role of differential reinforcement is therefore critical to understanding control by elapsed time.