A simple optical method for producing two identical stimuli moving in opposite directions

A problem in experiments on adaptation to moving stimuli is the tendency of subjects to track the stimuli visually, which can complicate results. A simple optical method is described which eliminates this tendency by presenting two identical stimuli moving in opposite directions.     

A study of area conservation using a simple method of adjustment

The method of adjustment was adapted to study conservation of area with Papua New Guinea High School students. Subjects were shown a standard field, representing “a block of land”, with a “house” in each corner. An identical comparison field. with adjustable borders was presented under one of two conditions. In one condition the houses were placed along one side, and in the other they were placed randomly about the field. Non-conservers were invited to adjust the borders of the comparison field to match the area of the standard. Non-conservers in the Edge condition reduced, and those in the Random condition increased, the size of the comparison field.     

A cryogenic implant for producing reversible functional brain lesions

This paper describes a permanently implanted device for applying cold to localized parts of the brain surface in order to produce reversible functional lesions in behaving animals. It consists of an array of several independently controlled stainless steel tubing loops, each shaped to fit a separate brain area. Cooled alcohol is pumped through the tubing and temperatures are monitored with attached thermocouples. Implanted loops can be cooled to 0°C within 15 sec, and temperatures can be maintained at ±1°C of accuracy. Tissue tolerance is excellent: Implants have been demonstrated to last up to 1 year or more. Methods and materials for construction are discussed.     

A simple device for producing synchronous and asynchronous binocular flicker

Many studies on binocular integration have compared in-phase and out-of-phase flicker stimulation. A new method of producing such stimulation is described. It differs from previous designs in that a combination of polarizers is used rather than mechanical light choppers or electronic flashers. The arrangement produces sinusoidal luminance pulses that can be presented with any degree of asynchrony between the two eyes.     

A method for producing random visual textures

Textures composed of randomly shaped black and white areas may be produced from high-contrast photographs of a mixture of white and black-dyed rice. Moderate control of black-to-white ratio and many randomizations at a given ratio are possible. This method is cheaper than computer generation and better controlled than the more inexpensive methods.     

A simple method of factor analysis

A simple method for extracting correlated factors simultaneously is described. The method is based on the idea that the centroid pattern coefficients for the sections of unit rank of the complete matrix may be interpreted as structure values for the entire matrix. Only the routine centroid average process is required.     

A simple general method for oblique rotation

A simple and very general algorithm for oblique rotation is identified. While motivated by the rotation problem in factor analysis, it may be used to minimize almost any function of a not necessarily square matrix whose columns are restricted to have unit length. The algorithm has two steps. The first is to compute the gradient of the rotation criterion and the second is to project this onto a manifold of matrices with unit length columns. For this reason it is called a gradient projection algorithm. Because the projection step is very simple, implementation of the algorithm involves little more than computing the gradient of the rotation criterion which for many applications is very simple. It is proven that the algorithm is strictly monotone, that is as long as it is not already at a stationary point, each step will decrease the value of the criterion. Examples from a variety of areas are used to demonstrate the algorithm, including oblimin rotation, target rotation, simplimax rotation, and rotation to similarity and simplicity simultaneously. While it may be, the algorithm is not intended for use as a standard algorithm for well established problems, but rather as a tool for investigating new methods where its generality and simplicity may save an investigator substantial effort.The author would like to thank the review team for their insights and recommendations.     

A simple method for pairwise monotone regression

A simple method of monotone regression is described based on the principle of minimizing pairwise departures from monotonicity.     

A simple method to stand outside oneself

Here we outline a simple method of using two mirrors which allows one to stand outside oneself. This method demonstrates that registration of vision with touch and proprioception is crucial for the perception of the corporeal self. Our method may also allow the disassociation of taste from touch, proprioception, and movement.     

A method of producing a three-dimensional cathode ray tube display

A method of producing a true three-dimensional cathode ray tube display has been developed. It has been used to plot three-dimensional vectorcardiograms, bar graphs, and would probably be useful to research in visual perception.     

A simple method for semiquantitative assessment of thermesthesia

A technically simple method based on the Peltier effect was employed to determine semiquantitatively thermesthesia in normal individuals, patients with functional disorders, and patients with cortical and spinal complaints and peripheral affections of the CNS. The results demonstrate the suitability of the method in principle for use in routine examination.     

A simple method using a single video camera to determine the three-dimensional position of a fish

In the present paper, we describe a method for recording the coordinates of a fish in an aquarium in a three-dimensional space, using a single video camera and a mirror. We use photogrammetic equations for this, considering the image obtained in the mirror as a virtual image obtained by a second camera. A transformation of the coordinate system is required to express the obtained coordinates in anx,y,z system defined by the edges of the aquarium. The accuracy of the proposed method was estimated, and errors in extreme conditions were found to be 0.8% to 1.2 %, compared with the dimensions of the aquarium used in the test.     

A simple graphical method for orthogonal rotation of axes

A simple method of making orthogonal rotations by projecting coordinates from one plot to another is presented. An easily constructed apparatus for rapid and accurate work is described in detail. By the technique proposed 12 to 15 rotations of pairs of axes involving 20 test variables can be completed per hour by a practiced technician.