Evidence for the involvement of two areas of the zebra finch forebrain in sexual imprinting

Sexual imprinting in male zebra finches is a two-step process, including an acquisition period early in life and a stabilization process normally occuring during the first courtship attempts of the male. During the acquisition period, a young male learns about its social environment. During stabilization, which can be delayed experimentally until day 100, it develops a preference for the appropriate object for courtship behavior on the basis of its previous and acute experience. Thereafter, this preference cannot be altered again. Exploring the physiological basis for imprinting, we have previously shown that the neurons of two forebrain areas (ANC and HAD) increase their spine density in the course of the stabilization process, while in two other areas (MNH and LNH) a decrease of spine density can be observed. With the present experiments, we tested the idea that the spine density decrease in MNH and LNH is the anatomical manifestation of the imprinting process. Previous behavioral experiments have shown that exposure to a nestbox after 100 days of age stabilizes the sexual preference of a zebra finch male as well as does exposure to a female. The present study shows that nestbox exposure also reduces the spine density in MNH and LNH, but has no effect on ANC and HAD. It has also been shown previously that treating males with an antiandrogen between days 40 and 100 affects the final preference of a male. The present experiment indicates that the same treatment affects spine growth during development in MNH and LNH and prevents the increase of spine density within HAD and ANC normally induced by exposure to a female. The results are interpreted as strong evidence for the involvement of MNH and LNH in sexual imprinting.     

Perception of coherent motion in random dot displays by pigeons and humans.

Pigeons and humans were required to discriminate coherent from random motion in dynamic random dot displays. Coherence and velocity thresholds were determined for both species, and both thresholds were found to be substantially higher for pigeons than for humans. The results are discussed with reference to differences in motion processing in mammals and birds. It is suggested that the inferior motion sensitivity of pigeons can be attributed to poorer spatiotemporal motion integration.     

Contemporary family therapy in the United States

Major issues in contemporary family therapy in the United States are described. Issues from outside the field impacting family therapy include health care reform, family 'values', multiple forms of 'family', and the growing aging population. Issues within the field include the challenge of social construction theory, the decline of the expert, the feminist critique, sensitivity to culture, rediscovering individuals within families, focus on strengths and resources, a both–and attitude toward collaboration with other professionals, emphasis upon the person of the therapist, and convergence of 'schools' of family therapy. Therapists in the United States are also opening up the private process of therapy through reflecting teams, including clients in therapist thinking, multi-family groups, and through psychoeducational groups. Finally, attempts to bridge the gap between research and practice are analyzed.     

Responses to mirror-image stimulation in jungle crows (Corvus macrorhynchos)

Four jungle crows (Corvus macrorhynchos) were exposed to a mirror placed either vertically or horizontally. The most frequently observed behaviors were pecking at the mirror and wing flapping when looking toward the mirror. These behavior patterns, which were only rarely observed when the mirror was reversed, can be interpreted as aggressive behaviors against a conspecific. The vertical mirror evoked the behaviors more often than the horizontal mirror. The present results suggest that crows perceive their mirror image as an image of a conspecific, not as their own. Received: 16 December 1999 / Accepted after revision 29 January 2000     

A semiautomatic method for adding behavioral data to videotape records in combination with the Noldus Observer system

The Observer 3.0 (Noldus, 1991) was used as the base for a time-saving fine analysis of animal behavior. A PC controlled a shuttlebox and a shuttlebox control unit. Learning behavior was recorded on videotapes by an S-VHS camcorder with vertical interval time code (VITC), which was used to generate an observational data file (ODF). The observational system was enhanced by automatically recorded status signals from the PC as event markers on the soundtrack of the videotape. These signals were used to subdivide a training session into numbered trials during generation of the ODF. They were later used for a PC-aided fine analysis of behavioral events, such as attention responses (AR) and orienting responses (OR) during shuttlebox learning. In this way, a large number of both automatically inserted PC event markers and manually inserted, key-defined behavioral events were registered and analyzed effectively in a semiautomatic fashion. The system is illustrated with an analysis of shuttlebox avoidance data from gerbils (Meriones unguiculatus).     

The attentional blink with targets in different spatial locations

When two targets (T1 and T2) are displayed in rapid succession, accuracy of T2 identification varies as a function of the temporal lag between the targets (attentional blink, AB). In some studies, performance has been found to be most impaired at Lag 1—namely, when T2 followed T1 directly. In other studies, T2 performance at Lag 1 has been virtually unimpaired (Lag 1 sparing). In the present work, we examined how Lag 1 sparing is affected by attentional switches between targets displayed in the same location or in different locations. We found that Lag 1 sparing does not occur when a spatial shift is required between T1 and T2. This suggests that attention cannot be switched to a new location while the system is busy processing another stimulus. The results are explained by a modified version of an attentional gating model (Chun & Potter, 1995; Shapiro & Raymond, 1994).     

Displacement limit (dmax) of sampled directional motion: direct and indirect estimates

The maximum displacement at which directional motion can be seen, known as dmax, has been said to define the spatial limits of the short-range motion system. Turano and Pantle (1985) used duration of motion aftereffect (MAE) to estimate the spatial limit of the short-range system, the assumption that dmax (a direct measure of motion perception) and MAE (an indirect measure) are equivalent indices of the same underlying perceptual process. In a series of four experiments, we examined this assumption by measuring dmax and duration of MAE across a range of displacements, stimulus waveforms (sine- or square-wave gratings), and spatial frequencies. We found that dmax and duration of MAE were affected differently by changes in the same variables. Therefore, we concluded that the two indices cannot be regarded as equivalent measures of the spatial limits of the short-range process. Two novel effects that separated MAE from motion detection are described, and suggestions for exploring them are outlined.     

Recurrence quantification analysis of eye movements

Recurrence quantification analysis (RQA) has been successfully used for describing dynamic systems that are too complex to be characterized adequately by standard methods in time series analysis. More recently, RQA has been used for analyzing the coordination of gaze patterns between cooperating individuals. Here, we extend RQA to the characterization of fixation sequences, and we show that the global and local temporal characteristics of fixation sequences can be captured by a small number of RQA measures that have a clear interpretation in this context. We applied RQA to the analysis of a study in which observers looked at different scenes under natural or gaze-contingent viewing conditions, and we found large differences in the RQA measures between the viewing conditions, indicating that RQA is a powerful new tool for the analysis of the temporal patterns of eye movement behavior.     

Social attention and real-world scenes: the roles of action, competition and social content

The present study examined how social attention is influenced by social content and the presence of items that are available for attention. We monitored observers' eye movements while they freely viewed real-world social scenes containing either 1 or 3 people situated among a variety of objects. Building from the work of Yarbus (1965/1967) we hypothesized that observers would demonstrate a preferential bias to fixate the eyes of the people in the scene, although other items would also receive attention. In addition, we hypothesized that fixations to the eyes would increase as the social content (i.e., number of people) increased. Both hypotheses were supported by the data, and we also found that the level of activity in the scene influenced attention to eyes when social content was high. The present results provide support for the notion that the eyes are selected by others in order to extract social information. Our study also suggests a simple and surreptitious methodology for studying social attention to real-world stimuli in a range of populations, such as those with autism spectrum disorders.