Observational learning of two visual discriminations by pigeons: a within-subjects design.

Pigeon's observational learning of successive visual discrimination was studied using within-subject comparisons of data from three experimental conditions. Two pairs of discriminative stimuli were used; each bird was exposed to two of the three experimental conditions, with different pairs of stimuli used in a given bird's two conditions. In one condition, observers were exposed to visual discriminative stimuli only. In a second condition, subjects were exposed to a randomly alternating sequence of two stimuli where the one that would subsequently be used as S+ was paired with the operation of the grain magazine. In a third experimental condition, subjects were exposed to the performance of a conspecific in the operant discrimination procedure. After exposures to conspecific performances, there was facilitation of discriminative learning, relative to that which followed exposures to stimulus and reinforcement sequences or exposures to stimulus sequences alone. Exposure to stimulus and food-delivery sequences enhanced performance relative to exposure to stimulus sequences alone. The differential effects of these three types of exposure were not attributable to order effects or to task difficulty; rather, they clearly were due to the type of exposure.     

Stimulus control of behavioral history.

Pigeons were exposed to two different reinforcement schedules under different stimulus conditions in each of two daily sessions separated by 6 hr (Experiments 1 and 2) or in a single session (Experiment 3). Following this, either a fixed-interval (Experiment 1) or a variable-interval schedule (Experiments 2 and 3) was effected in both stimulus conditions. In the first two experiments, exposure to fixed-ratio or differential-reinforcement-of-low-rate schedules led to response-rate, but not pattern, differences in subsequent performance on fixed- or variable-interval schedules that persisted for up to 60 sessions. The effects of reinforcement-schedule history on fixed-interval schedule performance generally were more persistent. In Experiment 3, a history of high and low response rates in different components of a multiple schedule resulted in subsequent response-rate differences under identical variable-interval schedules. Higher response rates initially occurred in the component previously correlated with high response rates. For 3 of 4 subjects, the differences persisted for 20 or more sessions. Previous demonstrations of behavioral history effects have been confined largely to between-subject comparisons. By contrast, the present results demonstrate strong behavioral effects of schedule histories under stimulus control within individual subjects.     

Identifying the Distress Cues that Influence Support Provision: A Paired Comparison Approach

ABSTRACT

Just as chemistry has methods for determining the composition of unknown substances, psychology needs, but has lacked, effective methods for identifying the “active ingredients” of social stimuli. We describe such a method and apply it to identify the verbal and nonverbal distress cues that serve as signals prompting others to provide social support. This method allowed us to identify 55 such cues. Furthermore, the cues that were salient in the minds of potential support providers depended on their goals. For example, when deciding whether someone needed support, negative nonverbal cues (e.g., distressed persons' fidgeting) were more salient, but when deciding whether one was willing to provide support, cues that suggested a positive outcome for the support seeker (e.g., distressed persons' positive attitude and open-mindedness) were more salient.     

APPLICATIONS OF A SEQUENTIAL ALTERNATING TREATMENTS DESIGN

We propose the use of a combined version of the alternating treatments and multiple baseline designs in situations in which a traditional baseline (no treatment) condition either does not provide an adequate contrast condition or is not feasible or practical due to clinical constraints. We refer to this design as a sequential alternating treatments design because two treatments are initially implemented in a random or counterbalanced fashion and are followed by a sequential change in one or both treatments across settings, subjects, or tasks. The effects of the independent variables are assessed first by analyzing the two series of data points representing the different treatments (relative effects) and then by assessing changes in one or both series, as application of the alternative treatment is introduced sequentially. The sequential application of treatment provides an analysis of control in the same manner as the multiple baseline design; the initial alternating treatments phase provides a contrast condition in much the same manner as a baseline condition. Applications of this design to the assessment of peer training and self-injurious behavior are described.     

‘Liars are less detailed’ …So what? Comparing two recall instructions to detect deception within-subject

Most deception research provides between-subject results (e.g., liars give on average less detailed accounts), which might be of limited value for professionals evaluating credibility on an individual basis. This study examines the optimal instructions of a within-subject multiple recalls strategy to detect deception. A total of 110 participants, divided into a Lie and Truth group, were randomly placed into four interview conditions: two Basic report-everything instructions (1), a Basic recall followed by an Open depth instruction (2), a Basic recall followed by the Verifiability Approach and Information Protocol (3), and two recalls with the Verifiability Approach and Information Protocol (4). All recalls were coded for total details and verifiable details. Group (lie and truth) × Recall (first and second) was only significant in condition 3, with truth tellers providing more verifiable details in the second recall than the first. A simple within-subject decision rule was derived, allowing a 76.9% discrimination rate. Professionals can optimally evaluate credibility using two recalls (Basic recall followed by Verifiability Approach and Information Protocol) and observing the evolution of verifiable details.