This article reports data sets aimed at the development of a detailed feature-space representation for a complex natural category domain, namely 30 common subtypes of the categories of igneous, metamorphic, and sedimentary rocks. We conducted web searches to develop a library of 12 tokens each of the 30 subtypes, for a total of 360 rock pictures. In one study, subjects provided ratings along a set of 18 hypothesized primary dimensions involving visual characteristics of the rocks. In other studies, subjects provided similarity judgments among pairs of the rock tokens. Analyses are reported to validate the regularity and information value of the dimension ratings. In addition, analyses are reported that derive psychological scaling solutions from the similarity-ratings data and that interrelate the derived dimensions of the scaling solutions with the directly rated dimensions of the rocks. The stimulus set and various forms of ratings data, as well as the psychological scaling solutions, are made available on an online website (https://osf.io/w64fv/) associated with the article. The study provides a fundamental data set that should be of value for a wide variety of research purposes, including: (1) probing the statistical and psychological structure of a complex natural category domain, (2) testing models of similarity judgment, and (3) developing a feature-space representation that can be used in combination with formal models of category learning to predict classification performance in this complex natural category domain.Keywords Feature-space representation . Similarity . Multidimensional scaling . Categorization A ubiquitous component of science education is learning the key categories of the target domain. For example, botanists are expert at identifying different types of plants; entomologists at insect identification; and geologists at identifying and classifying rocks. A long-term goal of the present project is to apply principles of category learning gleaned from the field of cognitive psychology to help guide the search for effective techniques of teaching categories in the science classroom. Our specific example target domain is the teaching of rock identification and classification in the geologic sciences. Learning such classifications is one of the primary early goals in geology courses in both the classroom and the field: Determining the rock categories that compose a given terrain is a first step in allowing the geologist to move toward his or her ultimate goal of making inferences about the geologic history of that terrain.There is an enormous variety of different techniques that might be used for the teaching of scientific classifications. For example, among the fundamental questions addressed in the cognitive psychology of category learning are: (i) Which training instances should be used? (ii) In what order should the instances be presented? (iii) What mixings of study versus testing should be applied? And (iv) Should the focus be on teaching general rules or learning by induction ...
The general view in psychological science is that natural categories obey a coherent, family-resemblance principle. In this investigation, we documented an example of an important exception to this principle: Results of a multidimensional-scaling study of igneous, metamorphic, and sedimentary rocks (Experiment 1) suggested that the structure of these categories is disorganized and dispersed. This finding motivated us to explore what might be the optimal procedures for teaching dispersed categories, a goal that is likely critical to science education in general. Subjects in Experiment 2 learned to classify pictures of rocks into compact or dispersed high-level categories. One group learned the categories through focused high-level training, whereas a second group was required to simultaneously learn classifications at a subtype level. Although high-level training led to enhanced performance when the categories were compact, subtype training was better when the categories were dispersed. We provide an interpretation of the results in terms of an exemplar-memory model of category learning.
Seismic anisotropy in the upper mantle can be explained by crystallographic mineral alignment achieved through dislocation motion. The physical mechanism of mineral alignment requires upper mantle shear flow which reorients and aligns minerals by dislocation glide and climb governed by the dominant glide syst. em of each mineral. The dominant glide systems are assumed to be [100](010) for olivine and [001](100) for the pyroxenes. These yield a predominantly orthorhombic fabric with the olivine [100] and the pyroxene [001] axes aligned in the upper mantle flow direction and the olivine [010] and the pyroxene [100] axes aligned normal to the upper mantle flow plane. These glide systems have a threshold temperature of enhanced mobility of 1100-1200 K, which yields a solid-state, thermally defined lithosphere-asthenosphere boundary in a olivine-pyroxene mantle consistent with recent seismic determinations of the thickness of the lithosphere. Mantle anisotropy due to mineral alignment is then actively maintained below this boundary (a•thenosphere and mesosphere) and is a fossil state above this boundary (lithosphere). We •.!se the dominant glide systems to establish the crystallographic orientation of olivine and pyroxene in calculating the maximum seismic anisotropy of two petrologic models (pyrolite and piclogite) for the upper mantle by an extrapolation of single-crystal, anisotropic mineral elastic properties to a •epth of 400 km. The real-earth seismic anisotropy will be bound by the limits of maximum anisotropy from perfect mineral alignment and minimum anisotropy (isotropy) from random mineral alignment. The seismic anisotropy of the upper 220 km is best represented by the pyrolite model, which reduces to quasi-hexagonal symmetry with the unique axis in the direction of mantle flow. The Lehmann discontinuity is conjectured to be due to a change in composition from pyrolite to piclogite and therefore may represent a change in anisotropy. The piclogite model has orthorhombic symmetry •istinctly different from that of the pyrolite. The piclogite anisotropy model can appear quasi-isotropic, when measured by transverse isotropy parameterization, if the mantle flow is mainly horizontal with a horizontal shear plane (that is, the shear flow gradient dult /dR dominates). 0148-0227/86/004B-5212505.00 tropy in the upper mantle is due to crystallographic alignment of intrinsically anisotropic minerals, mainly olivine and the !•roxenes. Evidence for alignment of these minerals comes from studies of ophiolites [e.g., Christensen and Lundquist, 1982; Christensen, 1984] and upper mantle xenoliths [e.g., Mercier and Nicolas, 1975]. Thus not only is there evidence for substantial alignment of olivine (ol}, but there is also evidence for alignment of orthopyroxene (opx) and weak alignment of clinopyroxene {cpx} (e.g., diopside, see Peselnick et al. [1974]). The petrofabric evidence shows that ol [100] and opx [001] tend to be aligned in the same direction, that ol [010] and opx [100] tend to be aligned in the same direction, and...
The Khutzeymateen assemblage records a portion of the polyphase deformation experienced by rocks within the core of the Coast Plutonic Complex. This series of deformational events probably took place during Late Cretaceous to Early Eocene regional orogenic activity. The Khutzeymateen assemblage is dominated by metamorphosed graywackes and volcaniclastic material. The earliest recognizable deformation involves thrust faulting that juxtaposed rocks of the Khutzeymateen assemblage and Central Gneiss Complex. The next deformational event produced isoclinal folds (F1), a penetrative foliation (S1), and a strong mineral lineation (L1). Both F1 and L1 have a 340°, 15 °orientation. Peak metamorphism (P = 450 ± 50 MPa, T = 650° ± 50 °C) was synchronous with this isoclinal folding event. F1 folding was followed by a brittle chevron folding event (F2) with a 335°, 20° orientation. There is a strong lithologic control on the development of F2 minor folds, which are developed predominantly within regularly layered quartzo-feldspathic lithologies. Open F3 folds (065°, 35°) may have developed by buckling related to differential uplift on the Larch Creek Fault. Post-F3 faults and minor shear zones are developed mostly in the eastern half of the area. The different deformational styles associated with the different deformational events probably reflect variations in the position of this group of rocks with respect to the surface during a single orogenic episode.
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