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Face recognition is one of the best cognitive skills people have. We generally recognize faces with very little effort, despite large variations in skin tone, viewpoint, and expression. Discussion of [...], The face inversion effect (FIE) is a reduction in recognition performance for inverted faces compared with upright faces. Several studies have proposed that a type of configural information, called second-order relational information, becomes more important with increasing expertise and gives rise to the FIE. However, recently it has been demonstrated that it is possible to obtain an FIE with facial features presented in isolation, showing that configural information is not necessary for this effect to occur. In this article we test whether there is a role for configural information in producing the FIE and whether second- or first-order relational information is particularly important. In Experiment 1, we investigated the role of configural information and local feature orientation by using a new type of 'Thatcherizing' transformation on our set of faces, aiming to disrupt second-order and local feature orientation information but keeping all first-order properties unaltered. The results showed a significant reduction in the FIE for these 'new' Thatcherized faces, but it did not entirely disappear. Experiment 2 confirmed the FIE for new Thatcherized faces, and Experiment 3 establishes that both local feature orientation and first-order relational information have a role in determining the FIE. KEYWORDS: inversion effect, configural information, featural information, Thatcher illusion, face recognition

Pinniped body lengths from different species were obtained and subsequently correlated with growth-rate factors and body size variability studies within and among species. Data evaluation was based on a nonlinear fitting of growth curves which provided asymptotic size estimation, growth-body size parameters and intraspecies variability assessment. The results showed that the body length growth in pinnipeds could not be generalized using only one growth equation. This proved that size and development pattern variations existed among pinnipeds.

A sensor for the rapid (10-ms response time) measurement of vapors from the hydrocarbon-based fuels JP-8, DF-2, and gasoline is described. The sensor is based on a previously reported laser-mixing technique that uses two tunable diode lasers emitting in the near-infrared spectral region [Appl. Opt. 39, 5006 (2000)] to measure concentrations of gases that have unstructured absorption spectra. The fiber-mixed laser beam consists of two wavelengths: one that is absorbed by the fuel vapor and one that is not absorbed. Sinusoidally modulating the power of the two lasers at the same frequency but 180 [degrees] out of phase allows a sinusoidal signal to be generated at the detector (when the target gas is present in the line of sight). The signal amplitude, measured by use of standard phase-sensitive detection techniques, is proportional to the fuel-vapor concentration. Limits of detection at room temperature are reported for the vapors of the three fuels studied. Improvements to be incorporated into the next generation of the sensor are discussed. OCIS codes: 120.0120, 120.1880, 140.2020, 280.0280.

We describe the development and characterization of a near-infrared diode-laser-based sensor to measure the vapor from trace gases having unstructured absorption spectra. The technique uses two equal amplitude-modulated laser beams, with the modulation of the two lasers differing in phase by 180 deg. One of the laser beams is at a wavelength absorbed by the gas [for these experiments, vapor is from pyridine ([C.sub.5][H.sub.5]N), and the second laser beam is at a wavelength at which no absorption occurs. The two laser beams are launched onto near-coincident paths by graded-index lens-tipped optical fibers. The mixed laser beam signal is detected by use of a single photodiode and is demodulated with standard phase-sensitive detection. Data are presented for the detection and measurement of vapor from pyri-dine ([C.sub.5][H.sub.5]N) by use of the mixed laser technique. The discussion focuses on experimental determination of whether a compound exhibits unstructured absorption spectra (referred to here as a broadband absorber) and methods used to maximize sensitivity. [C] 2000 Optical Society of America OCIS codes: 120.0120, 120.1880, 140.2020, 280.0280.