Signalling games: evolutionary convergence on optimality

Horn's division of pragmatic labour (Horn, 1984) is a universal property of language, and amounts to the pairing of simple meanings to simple forms, and deviant meanings to complex forms. This division makes sense, but a community of language users that do not know it makes sense will still develop it after a while, because it gives optimal communication at minimal costs. This property of the division of pragmatic labour is shown by formalising it and applying it to a simple form of signalling games, which allows computer simulations to corroborate intuitions. The division of pragmatic labour is a stable communicative strategy that a population of communicating agents will converge on, and it cannot be replaced by alternative strategies once it is in place.

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The Critical Test

Darwin's Psychology ◽

10.1093/oso/9780198708216.003.0009 ◽

2020 ◽

pp. 292-314

Author(s):

Ben Bradley

Keyword(s):

Young Children ◽

Simple Form ◽

Human Agency ◽

Human Action ◽

Biographical Sketch ◽

Critical Test ◽

Group Life ◽

Complex Development ◽

Complex Forms ◽

Preverbal Infants

Darwin used observations of infants as evidence for his evolutionary hypotheses about human agency, in three ways. First, human actions that appear fully formed at the start of life, like sucking, were deemed reflexes or instinctive fruits of evolution. Second, infant actions show in a clear and simple form the foundations of human agency. Third, when there is no direct way of proving how complex forms of human action evolved, their growth in infancy provides a working model for natural, simple-to-complex development that is analogous to evolution. Two texts exploit these arguments: Expression (1872) and ‘A Biographical Sketch of an Infant’ (1877). The former concentrates on crying and weeping. The latter focuses on some of the distinctively human forms of agency described in Descent. A key omission in the evidence Darwin’s infant observations provide for his theory is a test of infants’ capacity for group-interaction. Evidence from such a test is critical to acceptance of Descent’s thesis that adaptations to group-life ground the most distinctive forms of human behaviour. Only recently have scientists sought this evidence. From these we know that preverbal infants do have a capacity for ‘groupness.’ Darwin’s observations of young children show a robustness and prescience borne out by contemporary research.

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Organization of the Pellicle and the Muciferous Glands in Euglena Gracilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100067510 ◽

1970 ◽

Vol 28 ◽

pp. 104-105

Author(s):

Hilton H. Mollenhauer ◽

W. Evans

Keyword(s):

Plasma Membrane ◽

Euglena Gracilis ◽

Complex Forms ◽

Secondary Periodicity

The pellicular structure of Euglena gracilis consists of a series of relatively rigid strips (Fig. 1) composed of ridges and grooves which are helically oriented along the cell and which fuse together into a common junction at either end of the cell. The strips are predominantly protein and consist in part of a series of fibers about 50 Å in diameter spaced about 85 Å apart and with a secondary periodicity of about 450 Å. Microtubules are also present below each strip (Fig. 1) and are often considered as part of the pellicular complex. In addition, there may be another fibrous component near the base of the pellicle which has not yet been very well defined.The pellicular complex lies underneath the plasma membrane and entirely within the cell (Fig. 1). Each strip of the complex forms an overlapping junction with the adjacent strip along one side of each groove (Fig. 1), in such a way that a certain amount of sideways movement is possible between one strip and the next.

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A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055904 ◽

1982 ◽

Vol 40 ◽

pp. 722-723 ◽

Cited By ~ 1

Author(s):

R. Gronsky

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Computer Simulations ◽

Structural Characteristics ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133874 ◽

1990 ◽

Vol 48 (2) ◽

pp. 56-57

Author(s):

C P Scott ◽

A J Craven ◽

C J Gilmore ◽

A W Bowen

Keyword(s):

Energy Loss ◽

Multiple Scattering ◽

Simple Form ◽

Single Scattering ◽

Low Loss ◽

Characteristic Energy ◽

Normal Method ◽

Fitting In ◽

Electron Energy Loss ◽

Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

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Multislice calculations for quasi-periodic and non-periodic objects

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173820 ◽

1990 ◽

Vol 48 (4) ◽

pp. 138-139

Author(s):

R. Herrera ◽

A. Gómez

Keyword(s):

Electron Diffraction ◽

Computer Simulations ◽

Periodic Table ◽

Amorphous Materials ◽

Space Group ◽

Essential Step ◽

Shape Effects ◽

Atomic Scattering ◽

Diffraction Patterns ◽

Periodic Continuation

Computer simulations of electron diffraction patterns and images are an essential step in the process of structure and/or defect elucidation. So far most programs are designed to deal specifically with crystals, requiring frequently the space group as imput parameter. In such programs the deviations from perfect periodicity are dealt with by means of “periodic continuation”.However, for many applications involving amorphous materials, quasiperiodic materials or simply crystals with defects (including finite shape effects) it is convenient to have an algorithm capable of handling non-periodicity. Our program “HeGo” is an implementation of the well known multislice equations in which no periodicity assumption is made whatsoever. The salient features of our implementation are: 1) We made Gaussian fits to the atomic scattering factors for electrons covering the whole periodic table and the ranges [0-2]Å−1 and [2-6]Å−1.

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Computer simulations for the TEM bend contour technique

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163137 ◽

1996 ◽

Vol 54 ◽

pp. 134-135

Author(s):

Vladimir Yu. Kolosov ◽

Anders R. Thölén

Keyword(s):

Computer Simulations ◽

Real Space ◽

Advantages And Disadvantages ◽

Short Overview ◽

Diffraction Contrast ◽

Beam Method ◽

Convergent Beam ◽

Contour Technique

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.

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Individual Differences in Mental Rotation

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169/a000184 ◽

2013 ◽

Vol 60 (3) ◽

pp. 164-171 ◽

Cited By ~ 20

Author(s):

Peter Khooshabeh ◽

Mary Hegarty ◽

Thomas F. Shipley

Keyword(s):

Individual Differences ◽

Mental Rotation ◽

Response Times ◽

Task Demands ◽

Mental Rotation Task ◽

Imagery Ability ◽

Alternative Strategies

Two experiments tested the hypothesis that imagery ability and figural complexity interact to affect the choice of mental rotation strategies. Participants performed the Shepard and Metzler (1971) mental rotation task. On half of the trials, the 3-D figures were manipulated to create “fragmented” figures, with some cubes missing. Good imagers were less accurate and had longer response times on fragmented figures than on complete figures. Poor imagers performed similarly on fragmented and complete figures. These results suggest that good imagers use holistic mental rotation strategies by default, but switch to alternative strategies depending on task demands, whereas poor imagers are less flexible and use piecemeal strategies regardless of the task demands.

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