Two types of behavioral contrast in discrimination learning

Two groups of pigeons received daily discrimination training at two values on a line-tilt continuum. S+ (VI 1) and S- (EXT) intervals alternated, and a 30-sec criterion of no responding to S- was required before S+ returned. Rates of responding to S+ showed two separate contrast effects: at an intermediate stage of training a high peak rate appeared which declined, later in training, to a stable level still in excess of the VI baseline rate. The peak rate was correlated with the total number of responses to S-, while the final rate was not; suggesting that the peak rate and final rate may not be functions of the same variable. These results were compared with performance on a red-green discrimination where the two stages were not so clear. A line-tilt discrimination was repeated with fixed length S- intervals terminated by TO, and showed the same contrast magnitude in the final rate without any peak. The peak rate was interpreted as an effect of the ;punishment' contingency where responding to S- prolongs S- for 30 sec, while the final rate was taken to be analogous to previous demonstrations of contrast.     

Statistical classification of black-capped (Poecile atricapillus) and mountain chickadee (Poecile gambeli) call notes

Both black-capped (Poecile atricapillus) and mountain chickadees (Poecile gambeli) produce a chick-a-dee call that consists of several distinct note types. In some regions, these 2 species live sympatrically, and it has been shown that 1 species will respond weakly to songs of the other. This suggests that chickadee song, and potentially other of their vocalizations, contains species-specific information. We tested the possibility that call notes were acoustically sufficient for species identification. Black-capped and mountain non-D notes were summarized as a set of 9 features and then analyzed by linear discriminant analysis. Linear discriminant analysis was able to use these notes to identify species with 100% accuracy. We repeated this approach, but with black-capped and mountain D notes that were summarized as a set of 4 features. Linear discriminant analysis was able to use these notes to identify species with 94% accuracy. This demonstrates that any of the note types in these chickadee calls possesses sufficient information for species classification.     

Acoustic mechanisms of note-type perception in black-capped chickadee (Poecile atricapillus) calls

Acoustic communication in black-capped chickadees (Poecile atricapillus) has been studied intensively, the "chick-a-dee" call being among the most well described. This call consists of 4 note types; chickadees perceive these notes as open-ended categories and do so in a continuous manner, with As more similar to Bs and Bs more similar to Cs. Acoustic features contributing to the note-type differentiation are unknown. Recent analyses suggested that certain acoustic features may play a role in note-type classification. Here, the authors tested black-capped chickadees in an operant-conditioning paradigm to determine which features were controlling note-type perception. The results suggest that the note pitch and the frequency modulation in the initial portion of the note control the perception of note types.     

Communication of Confidence as a Determinant of Group Judgment Accuracy

The performance of interacting groups is often viewed as a function of the groups' ability to identify and weight their better members' judgments (Einhorn, Hogarth, & Klempner, 1977). Accurate identification of the best group member is facilitated by individuals accurately assessing confidence in their own individual judgments and accurately communicating their confidence during group interaction (Sniezek & Henry, 1989). This paper examines the communication of confidence in interacting groups in two ways: by observing the performance of interacting groups for which confidence is anticipated to be communicated with high accuracy, and by observing the effects of changes in the group interaction setting that vary group members' ability to communicate confidence. This is achieved by examining the performance of a special type of interacting group, a laboratory financial market, that encourages relatively accurate communication of confidence and that can be modified to manipulate the extent to which confidence can be communicated. Results reveal generally high performance of groups which interact in settings that are conducive to communication of confidence, and significant learning from the interaction process by all group members (including the best member). Results also indicate a significant decrease in the performance of groups whose ability to communicate confidence during interaction is reduced.     

Group size and the framing effect:

Past research provides conflicting evidence for the role of value in the appearance of framing effects. In this study, the effects of frame and group size were examined using scenarios about less valuable and more valuable groups (animal vs. human). In addition, two picture manipulations, intended to increase the value of the group, were presented. Choice patterns differed for the human and animal groups, with participants exhibiting greater risk seeking overall for the human scenario and showing a framing effect for humans but not animals when no pictures were presented. A small group size increased the proportion of risky choices for both the animal and human scenarios. Presenting pictures with names did lead to framing effects for animals, but providing pictures or pictures and names eliminated framing effects for the human scenario. These findings suggest that the relationship between value and framing effects is a matter of degree.     

The role of sincere amends and perceived partner responsiveness in forgiveness

In a sample of 188 people currently in a romantic relationship, the authors examined the extent to which perceiving a partner as responsive and sincere in making amends relates to participants' forgiveness of a partner after a real‐life hurtful event. Specifically, it was predicted that sincere amends would be associated with greater forgiveness because it conveys that one's partner has understood and validated one's experience of the hurtful event. Results supported this mediational model. Further, exploratory analyses suggested that this meditational model is moderated by event severity and relationship satisfaction. Discussion focuses on understanding how this work might help to inform the dynamic process of forgiveness in couples.