Contour deletion as a method for identifying the weights of features underlying object recognition

A prerequisite for comparative work on object recognition is a method for identifying the features actually extracted from the form. The method introduced here with pigeons is discrimination training between two simple line drawings, followed by a generalization test in which contour is deleted from the reinforced drawing. In Condition 1, the line drawings were a square (S+) versus a triangle (S-); for Condition 2, the line drawings were planar projections of a cube (S+) versus a truncated pyramid (S-). The generalization decrement between responses to S+ and responses to test stimuli provides a quantitative index of the weight assigned to each feature. Contour deletion at either vertices or midsegments produced a decrement in the rate of responding, showing that each contour was represented as a feature. The generalization decrement to forms containing vertices with midsegments deleted was larger than the generalization decrement to forms containing midsegments with vertices deleted. Therefore, it appears that midsegments are weighted more strongly as features than vertices. Contour deletion provides a direct method for identifying the visual features underlying object recognition and lays a foundation for the development of comparative theories of object recognition.     

A Breath of Fresh Air: Absence and the Structure of Olfactory Perception

The question of whether we can perceive absences, in addition to ‘positives’, has received recent attention in the literature on the nature of vision and audition. The aim is to demonstrate that there can be objectless forms of perceptual consciousness; specifically, to show that such episodes can be distinguished from those in which there is merely no perception at all. The current article explores this question for the domain of olfaction, and argues that there can be experiences of the absence of odours, in addition to positive smell perception. Doing so sheds light upon the structure and spatial content of olfaction.     

Terror Management and Meaning: Evidence That the Opportunity to Defend the Worldview in Response to Mortality Salience Increases the Meaningfulness of Life in the Mildly Depressed

Previous terror management research has demonstrated that mildly depressed participants show a greater increase in worldview defense in response to reminders of their mortality than do nondepressed participants. Because the cultural worldview is posited to provide a meaningful conception of life, we hypothesized that mildly depressed participants who defend their worldview in response to mortality salience (MS) would increase their perception that the world is meaningful. A preliminary study first examined the Kunzendorf No Meaning Scale as a measure to assess perceptions of meaning. In the primary study, mildly depressed and nondepressed participants contemplated their own mortality or a neutral topic, evaluated two targets in a manner that either allowed them to defend their worldview or that did not, and then completed the Kunzendorf No Meaning Scale. As predicted, mildly depressed participants who had the opportunity to defend their worldview in response to mortality salience reported greater meaning in life than did mildly depressed participants who did not have the opportunity to defend their worldview, or mildly depressed participants not exposed to mortality salience. Implications for understanding and treating depression are briefly discussed.     

Social network predictors of bullying and victimization

This study examined whether bullies, victims, and aggressive victims (those who are both bullies and victims) differed on classroom social network variables, gender, and ethnicity. Survey data were collected from a primarily Latino and Asian sample of 1,368 Southern California 6th graders (mean age = 11.3 years). Logistic regression analyses were performed to determine whether network characteristics and ethnicity were associated with each of the outcome variables. Consistent with social cognitive theory, friends' participation in aggressive behaviors was positively associated with being a bully or an aggressive victim, and negatively associated with being a victim. Consistent with social dominance theory, the number of friendship nominations received was negatively associated with being a victim. Female bullies received fewer friendship nominations, but had a higher proportion of reciprocated friendships. Victims were disproportionately Asian. The findings suggest that bullying prevention efforts targeting highly aggressive students may also diffuse to their friends, and that assertiveness training in handling aggressive situations may successfully combat bullying and aggression.     

The effects of intertrial interval and instructional format on skill acquisition and maintenance for children with autism spectrum disorders

We replicated and extended the study by Koegel, Dunlap, and Dyer (1980) by examining the effects of 3 intertrial‐interval (ITI) durations on skill acquisition in 2 children with autism spectrum disorders. Specifically, we compared the effect of short (2 s), progressive (2 s to 20 s), and long (20 s) ITIs on participants’ mastery of tacts or intraverbals presented in massed‐trial and varied‐trial instructional formats. We also measured (a) stereotypic and problem behavior during the ITI, (b) maintenance of skills, and (c) responding to novel adults and settings. Results showed that short ITIs in a varied‐trial format produced the most efficient acquisition of skills; however, most ITI durations produced more efficient skill acquisition in a varied format compared to a massed format. The trial format and ITI duration associated with the lowest levels of stereotypic and problem behavior during the ITI and responding during maintenance and novel adult and setting probes differed across participants.     

The Changing Complexion of American Congregations

The only constant in life is change, or so goes the familiar refrain. But when it comes to research on multiracial congregations, studying change has largely been overlooked. Questions loom about the changing prevalence, leadership, and composition of racially diverse congregations. Using three waves of data from the National Congregations Study (1998, 2006, and 2012), we offer an overarching examination of racial composition in U.S. congregations across approximately 15 years. Both the percentage of multiracial congregations and the amount of racial/ethnic diversity in congregations have increased. The increase has been most dramatic in Protestant churches. In addition, blacks are more common in the pulpit and the pews of America's multiracial congregations than they were in the past. Blacks now surpass Latinos as the group most likely to worship with whites in multiracial congregations. Location and religious tradition continue to be influential factors in a congregation's racial diversity, but the significance of several congregational characteristics have changed over time. We discuss the implications of these findings.