Effects of identical context on visual pattern recognition by pigeons

The effects of identical context on pattern recognition by pigeons for outline drawings of faces were investigated by training pigeons to identify (Experiment 1) and categorize (Experiment 2) these stimuli according to the orientation of the mouth—an upright U shape representing a smiling mouth or an inverted U shape representing a sad mouth. These target stimuli were presented alone (Pair 1), with three dots in a triangular orientation to represent a nose and eyes (Pair 2), and with the face pattern surrounded by an oval (Pair 3). In Experiment 1, the pigeons trained with Pair 1 were most accurate, those trained with Pair 2 were less so, and those trained with Pair 3 failed to acquire the discrimination within eighty 100-trial sessions. The same ordering was found in Experiment 2 for pigeons trained on the three pairs simultaneously. The authors suggest that a contrasting finding in humans, the face superiority effect, might be due to a gain in discriminability resulting from recognition of the pattern as a face. An exemplar model of information processing that excludes linguistic coding accounts for the present results.     

Secure chaotic communication based on extreme multistability

Extreme multistability is the coexistence of a large number of attractors which can be reached by varying initial conditions. In this paper we show how this fascinating phenomenon can be used for secure communication. The main advantage of the communication system based on extreme multistability over a conventional chaos-based communication system is its exceptionally high security. The proposed system consists of two identical six-order oscillators; one in the transmitter and another one in the receiver, each exhibiting the coexistence of a large number of chaotic attractors. The oscillators are synchronized using a private channel through one of the system variables, while the information is transmitted via a public channel through another variable. The information is encrypted by varying the initial condition of one of the state variables in the transmitter using a chaotic map, adhering message packages in a staggered form to the coexisting attractors within the same time series of another state variable, which leads to switching among the coexisting chaotic attractors. To ensure communication security, the duration of the packages is shorter than synchronization time, so that synchronization attacks are ineffective.     

Factors Which Influence Precision of School-Level IRT Ability Estimates

The precision of the group-level IRT model applied to school ability estimation is described, assuming use of Bayesian estimation with precision represented by the standard deviation of the posterior distribution. Similarities and differences between the school-level model and the familiar individual-level IRT model are considered. School size and between-school variability, two factors not relevant at the student level, are dominant determinants of school-level precision. Under the multiple-matrix sampling design required for the school-level IRT, the number of items associated with a scale does not influence the precision at the school level. Also, the effects of school ability and item quality on school-level precision are often relatively weak. It was found that the use of Bayesian estimation could result in a systematic distortion of the true ranking of schools based on ability because of an estimation bias which is a function of school size.     

2. GENERAL COMMUNICATIONS

William L. Rivers and William T. Slater's Aspen Handbook on the Media: Research, Publications, Organizations (Palo Alto, Calif.: Aspen Program, 770 Welch Rd., Suite 453, 1973— $1.95, paper)

John McHale's The Changing Information Environment: A Selective Topography (Center for Integrative Studies, School of Advanced Technology, SUUT-Binghamton, Binghamton, N.Y. 13901—no price indicated).

Donis A. Dondis' A primer of Visual Literacy (Cambridge, Mass.: MIT Press, 1973— $9.95)

Anthony Sampson's The Sovereign State of ITT (New York: Stein &; Day, 1973—$10.00)

Z.A.B. Zeman's Nazi Propaganda (New York: Oxford University Press, 1973-.42.95, paper),

Edmund Carpenter's Oh What A blow That Phantom Gave Me! (New York: Holt, Rinehart &; Winston, 1973– $5.95),

Joe Morella, Edward Z. Epstein and Eleanor Clark's The Amazing Careers of Bob Hope: From Gags to Riches (New Rochelle, N.Y.: Arlington House, 1973—$8.95)     

Intelligence in the Wild: A Dispositional View of Intellectual Traits

Most accounts of intelligence are abilities-centric. They aim to explain intelligent behavior in terms of IQ or other measures of intellectual aptitude. However, several investigators have proposed that intelligent behavior in the wild—in everyday circumstances in which carefully framed tests do not tell people exactly what intellectual task to attempt—depends in considerable part on thinking dispositions. Definitionally, dispositions concern not what abilities people have, but how people are disposed to use those abilities. Everyday language includes a number of dispositional terms such as curiosity, open-mindedness, and skepticism. We review several dispositional constructs that researchers have investigated, sometimes under the label dispositions. The findings in trend show that dispositions are stable traits that help to explain intellectual performance over and above measures of intellectual aptitude. It is argued that a dispositional view of intelligence is warranted, and that it is an important area for continued research.