Alterations of the phonetic coding of speech sounds during repetition

One aspect of the comprehension of speech is the assignment of a phonetic representation to the sounds being heard. However, if a person listens to a meaningless syllable that is continually repeated, over time he will hear the syllable undergo a variety of changes. These changes are very systematic in character and represent alterations in the phonetic coding assigned to an unchanging sound stimulus. When the restricted nature of the changes that occur is analyzed phonetically, these changes are found to invlove a reorganization of the phones constituting the syllables and changes in a small number of distinctive features.     

The detection of visual intensity differences by pigeons

Pigeons were trained in a conditional discrimination procedure to discriminate between visual stimuli that varied in intensity. The magnitude of the intensity difference ranged from 0.80 to 0.05 logarithmic units. Psychometric functions were calculated from the data and the mean difference threshold for the 11 subjects was approximately 0.12 logarithmic units. A signal-detection analysis of the data suggested that stimuli that were below the calculated threshold were detectible to the subjects.     

BASIC subroutines for on-line experiments using Hewlett-Packard computers

Modifications of the Hewlett-Packard version of the BASIC language to permit its use in data acquisition and control of on-line experiments are described. The resulting software system is an easy-to-use interpretative compiler.     

A comparison of leverpress and head-poke discriminated Sidman avoidance

A discriminated Sidman avoidance procedure used by Forgione (1970) was replicated using a head-poke response instead of a leverpress as the avoidance operant. The resultant data were described in terms of the five dependent measures reported by Forgione. Head-poke avoidance was found to be more efficient than its leverpress counterpart and compared very favorably with the lever-disabling (or shock-timer-on) procedure used by Forgione to break up inefficient leverpress behavior patterns.     

A Plexiglas helmet and catheter protection assembly for chronic intravenous administration of drugs in small primates

A restraint and catheter-protection system consisting of a Plexiglas helmet and a nylon-tubing protector line has been developed to permit the long-term study of drug self-administration in monkeys. Frequent observations of monkeys in the system over a period exceeding a year have shown that the technique satisfies the requirements for long-term study of drug administration through an indwelling catheter and avoids several recurring problems inherent in other protection systems. Additional applications of the helmet and protector line are discussed.     

An inherent problem in certain constant-current stimulators

A basic and potentially dangerous problem that may occur in the use of triggered constant-current generators for stimulation is discussed in the general case. A solution with schematic illustration is presented for one specific constant-current generator, the CCS-1A manufactured by Electronics of Life Sciences, Inc.