Two visual mechanisms underlying the behavior of fish

Summary Studies of motion-detection by fish reveal two separate processes, which are hypothetically linked to different kinds of behavior. Furthermore, studies of interocular transfer with mirror-image shape discriminations also indicate two distinct mechanisms for the representation of visual directions. From these two kinds of experiment, it seems that visual processes subserving orientation of the fish to a moving object should be clearly distinguished from processes by which the fish evaluates the identity or activity of the object.

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Zusammenfassung Untersuchungen der Bewegungswahrnehmung von Fischen zeigen zwei verschiedene Prozesse auf, die mit zwei verschiedenen Verhaltensweisen in Beziehung gesetzt werden. Eine Analyse des interokularen Transfers mit Unterscheidung spiegelbildlicher Formen läßt außerdem erkennen, daß zwei verschiedene Mechanismen für die Repräsentation visueller Richtungen verantwortlich sind. Aus diesen Experimenten wird geschlossen, daß jene visuellen Prozesse, welche der Orientierung des Fisches in bezug auf ein sich bewegendes Objekt dienen, scharf unterschieden werden sollten von denen, durch welche der Fisch die Identität oder Aktivität des Objektes beurteilt.

     

Intake and Walk-in Procedures in a College Counseling Setting

Modifications of the intake procedure usually employed in counseling settings were adopted in order to provide students the opportunity for immediate contact with a counselor. Elimination of the waiting list, reduction in number of missed appointments, and reduction of length of counseling came about. Staff satisfaction with the new approach has been high and there would be opposition to reverting to the scheduled initial interview. Possible changes in the type of problem or clients' readiness for problem-solving were observed.     

A portable solid-state stimulus programmer

This paper describes a miniature solid-state timing device particularly useful for presenting repetitive signal sequences in classical conditioning experiments. The device uses transistors, silicon-controlled rectifiers, and four-layer diodes, and is powered by 20-hour rechargeable nickel-cadmium batteries. Visual monitoring is provided for the unelapsed ITI and battery charge. Ranges are; ITI, 15 sec. to 5 min., ISI, 0–50 secs., CS duration, 0.5 to 30 sec., US duration, 0.5 to 30 sec. The CS and US durations are adjustable and the onset of the latter may be at any time after the CS onset. Cycling is continuous and automatic; the outputs are in the form of relay closures.     

Detection of auditory signals presented at random times

One hundred msec tones of 1000 Hz at four intensities were presented according to two Poisson schedules in a background of wide band noise and as increments to a 1000 Hz tone. Each 15 minute test session was run under fixed conditions and one of three instructions to detect the signals; the two Ss were free to respond at any time. The data analyzed were several inter-response and signal-response distributions, and they were compared with a theory due to Luce. Discrepancies between the theory and data indicate needed modifications of both the theory and the procedure.     

A computer program to find the best-fitting orthogonal factors for a given hypothesis

A modification of the quartimax computation for factor rotation is described in which a hypothesized factor pattern is given to the machine along with the data. The machine uses the pattern to select the subset of variables to which it will attend when rotating in a given plane, in order to find an orthogonal solution which closely fits the hypothesis. The program also provides a measure of the goodness of this fit. The program can utilize pattern matrices that reflect only partial hypotheses as to the nature of the factors, as well as those that specify highly determined simple structure.     

Evidence

Conclusion We can now see, perhaps, what merits if any this definition has. It ties in the concept of evidence with that of law, and requires us to support our claim that some fact (or statement) is evidence for another by pointing out the science, and within it the law (or what meets the tests of being acceptable as such) whose existence alone justifies us in assuming that a certain conditional statement qualifies as acceptable as nomological. Whoever claims that a certain fact is evidence for another is required to justify his assumption that there exists a certain law. That in some sense there are such justifiable assumptions is clear from the existence of natural sciences and technologies based upon them. But it will turn out that in many cases it is impossible, as of a given moment, to make out a case for the claim that a certain conditional statement, required to support the view that a certain fact is evidence for another, is nomological. In such cases we are able to draw a clear line between what someone may think or claim is evidence, and what we have reasonable grounds for accepting as such. In short the concept offers us a principle of demarcation between justified and unjustified claims for the evidential nature of facts (or statements) offered as such. If this is not a very impressive achievement still it is not wholly contemptible, considering the confusion that prevails among many people concerning the question of evidence.     

Investigations of a mirror-image transfer effect in pigeons

In two separate experiments, pigeons trained binocularly to peck a key on which an oblique line (e.g., 60 degrees counter-clockwise rotation from horizontal) was projected yielded bi-modal angularity generalization gradients in extinction, with peaks of responding at both the training stimulus and its mirror image (in this case 120 degrees ). This mirror-image transfer effect may be analogous to an "octave effect" in auditory generalization, but Mello's finding of a mirror-image reversal transfer effect following monocular training in pigeons suggests an alternative interpretation.