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Background. Strong evidence supports the beneficial impact of exercise on cancer patients. However, the provision of exercise programs in Germany is highly heterogeneous. Therefore, the network OnkoAktiv (OA) enables patient consultations and referrals from coordinating regional OA centers (RE) into community-based exercise programs (CBEP). Objective. The aim of this study was to identify barriers and facilitators for the implementation of OA network structures from the perspective of RE and certified CBEP. Methods. This evaluation was executed in a sequential mixed methods design. We conducted 16 qualitative interviews with each leader in RE and the certified CBEP. Then, 89 certified CBEP were invited to a quantitative, cross-sectional survey. Results. We identified 11 facilitators each for RE and certified CBEP, 7 barriers for RE and 5 for certified CBEP. Barriers dealt with, for example, financing OA network structures, a lack of knowledge of exercise trainers, inadequate patient referral, and missing collaborations by healthcare professionals (HCPs). Most of the named facilitators were adequate internal organizational resources, support and reachability of OA staffs, and collaboration with HCPs. Conclusion. Our findings indicate different challenges for the implementation of OA network structures. Future implementation efforts should consider the evaluation of individual barriers and the development of specific solutions.

Pigeons were trained in a conditional discrimination paradigm to differentiate successively presented visual arrays according to the relative number of their elements. Transfer tests with novel stimuli demonstrated that they discriminated the categories of “many” (6 or 7) from “few” (1 or 2) items. In further tests, other new stimuli were introduced that consisted not only of these training numerosities, but also of the intervening ones (3, 4, and 5). Variations in the birds’ discrimination performance corresponded to the order of stimuli on a numerosity dimension. This serial ordering was maintained when other factors such as brightness, size, shape, area, and contour of the elements were systematically controlled across tests. Smaller numerosities were somewhat better discriminated than those at the higher end of this test range.

By using a free-operant instrumental discrimination procedure, it was demonstrated that pigeons find two-dimensional mirror-image visual forms more difficult to distinguish than otherwise similar forms. Variations in orientation of the discriminanda exacerbated the relative confusa­ bility of mirror images. No significant difference was found in the pigeons' performance whether the birds were discriminating vertically or horizontally reflected mirror-image pairs. Mirror images of shapes were also shown to be less discriminable than upside-down versions of shapes. The similarity of mirror-image patterns is discussed in relation to the generalized recognition of bilaterally symmetrical forms by pigeons. Pigeons found an orientation discrimination task involving a 45° tilt comparatively hard. A second experiment with a discrete-trial conditional paradigm confirmed that discriminations of shape orientations can be difficult for these birds. The addition of shape cues improved the performance on the orientation discrimination task, more so when arbitrary shapes were employed than when mirror images were used, which indicates again that the latter were more difficult to discriminate than the former. The relative insensitivity to shape orientations is ascribed to normal ecological demands on pigeons. It is well documented that when humans have to judge visual patterns as being the same as or different from sample patterns, they find it more difficult when the patterns are mirror images than when the patterns bear an arbitrary rela­ tion to each other. In other words, they find the members of mirror-image pairs to be perceptually similar. 1 Though intui­ tively not surprising, the deeper reasons for this are by no means altogether clear. It is likely that the similarity reflects the properties of fundamental strategies of information pro­ cessing that are wired into the mammalian visual system (Bornstein, Gross, & Wolf, 1978; Bradshaw, Bradley, & Pat­ terson, 1976; Corballis & Beale, 1976). Whatever its explanation, the confusability of mirror im­ ages often markedly affects the further processing of visual information. Humans, for example, yield a distinctly different performance when discriminating variously rotated visual shapes if the patterns involved are mirror-image pairs rather than arbitrarily different pairs of patterns. In the former instance, the time they take to decide whether two patterns are identical or not rises steeply with the angular orientation mismatch between the patterns (mental rotation; Shepard & Cooper, 1982). In the latter case the reaction times are mark­ edly shorter and not a function of the degree of orientation disparity (White, 1980). This conclusion is not fundamentally