Visual symmetry recognition by pigeons

Summary Pigeons learned to discriminate a large number of bilateral symmetric and asymmetric visual patterns successively projected on the pecking-key of an operant conditioning chamber. Responses to the positive stimuli were reinforced according to a variable interval schedule. Once acquisition was complete generalization trials, involving sets of new stimuli, were instituted under extinction. The birds classified these novel test stimuli with high accuracy throughout, according to their symmetry or asymmetry. Their performance was not disturbed by sets of test stimuli whose geometrical style differed considerably from the training stimuli. Pigeons were even able to discriminate when only allowed the use of one eye. The generalization series were partly designed to test some classical symmetry recognition theories. None was found to be adequate. Subsidiary experiments suggested that most pigeons have a slight spontaneous preference for asymmetric patterns and that symmetry/asymmetry differences can aid pattern discrimination learning at an early stage. It is concluded that pigeons, much like humans, can discriminate bilaterally symmetric from non-symmetric visual forms in a concept-like, generalizing way. The ontogenetic and phylogenetic development of this competence is considered. A novel symmetry recognition hypothesis based on spatial frequency analysis and neuronal feature-detector considerations is proposed.     

On Some Generalizations of the Concept of Partition

There are well-known isomorphisms between the complete lattice of all partitions of a given set A and the lattice of all equivalence relations on A. In the paper the notion of partition is generalized in order to work correctly for wider classes of binary relations than equivalence ones such as quasiorders or tolerance relations. Some others classes of binary relations and corresponding counterparts of partitions are considered.     

‘You have to treat the person,not the mouth only’: UK dentists’ perceptions of communication in patient consultations

Effective communication between patients and health professionals is a key component of patient-centred care. Although there is a large body of literature focusing on doctor-patient communication, there has been limited research related to dentist-patient communication, especially presented from the dentists’ perspective. The aim of our study was to explore UK dentists’ perceptions of communication in their consultations, and the factors they perceive may influence this. We conducted semi-structured interviews with eight dentists in UK dental NHS practices. Thematic analysis revealed three themes (‘Treating the whole person’, ‘Barriers to patient-centred communication’ and ‘Mutuality of communication’), which reflected the dentists’ perceptions of their own communication during consultations, the patients’ interaction skills, attitudes (and characteristics that may affect them), and external factors, such as time constraints, that can influence dentist-patients’ encounters. These in-depth accounts are valuable, in that we see what dentists perceive is important, obstructive and facilitative. They report using a patient-centred approach in their everyday dental practice; however this is often difficult due to factors such as time constraints. Although they emphasized that the patient has an active role to play in the communication process, it may be the case that they also need to play their part in facilitating this.     

异体造血干细胞移植问题、发展与思考

异体造血干细胞移植(Allo-HSCT)已成为治疗恶性血液病及其他各种疾病的有效方法之一。在Allo-HSCT中由于供体和受体免疫屏障的存在。从而一开始就是一个供受体矛盾的对立统一的过程。对其中矛盾的研究和解决充满了辩证唯物的哲学思想。也促使Allo-HSCT技术不断发展。新的方法和理念不断出现。使Allo-HSCT治疗白血病的疗效不断提高。     

Cognitive Task Analysis for Implicit Knowledge About Visual Representations With Similarity Learning Methods

Visual representations are prevalent in STEM instruction. To benefit from visuals, students need representational competencies that enable them to see meaningful information. Most research has focused on explicit conceptual representational competencies, but implicit perceptual competencies might also allow students to efficiently see meaningful information in visuals. Most common methods to assess students’ representational competencies rely on verbal explanations or assume explicit attention. However, because perceptual competencies are implicit and not necessarily verbally accessible, these methods are ill‐equipped to assess them. We address these shortcomings with a method that draws on similarity learning, a machine learning technique that detects visual features that account for participants’ responses to triplet comparisons of visuals. In Experiment 1, 614 chemistry students judged the similarity of Lewis structures and in Experiment 2, 489 students judged the similarity of ball‐and‐stick models. Our results showed that our method can detect visual features that drive students’ perception and suggested that students’ conceptual knowledge about molecules informed perceptual competencies through top‐down processes. Furthermore, Experiment 2 tested whether we can improve the efficiency of the method with active sampling. Results showed that random sampling yielded higher accuracy than active sampling for small sample sizes. Together, the experiments provide the first method to assess students’ perceptual competencies implicitly, without requiring verbalization or assuming explicit visual attention. These findings have implications for the design of instructional interventions that help students acquire perceptual representational competencies.     

退步原来是向前

从契此的“手把青苗插满田,低头便见水中天,六根清净方为道,退步原来是向前”偈中,反映了退让并不是完全的消极,有时反而是一种积极的进取,从而揭示出丰富的人生哲理。