Mental rotation: An event-related potential study with a validated mental rotation task

Event-related potentials (ERPs) were recorded while subjects performed a validated mental rotation task, taken from the cognitive psychology literature. These ERPs show a late posterior negativity relative to a baseline condition requiring all of the same perceptual and cognitive processes except for the mental rotation itself. Our tentative identification of this posterior negativity with mental rotation is further supported by the finding that it varies systematically with the amount of mental rotation required on a trial by trial basis in the experimental task. We conclude that this late negativity is an ERP marker of the mental rotation process, and that this process engages primarily posterior brain regions.     

Automated Measurement of Mouse Freezing Behavior and its Use for Quantitative Trait Locus Analysis of Contextual Fear Conditioning in (BALB/cJ × C57BL/6J)F2 Mice

The most commonly measured mouse behavior in fear conditioning tests is freezing. A technical limitation, particularly for genetic studies, is the method of direct observation used for quantifying this response, with the potential for bias or inconsistencies. We report the use of a computerized method based on latency between photobeam interruption measures as a reliable scoring criterion in mice. The different computer measures obtained during contextual fear conditioning tests showed high correlations with hand-scored freezing; r values ranged from 0.87 to 0.94. Previously reported strain differences between C57BL/6J and DBA/2J in context-dependent fear conditioning were also detected by the computer-based system. In addition, the use of computer-scored freezing of 199 (BALB/cJ×C57BL/6J)F₂ mice enabled us to detect a suggestive gender-dependent chromosomal locus for contextual fear conditioning on distal chromosome 8 by QTL analysis. Automation of freeze scoring would significantly increase efficiency and reliability of this learning and memory test.     

Range of acceptable stimulus intensities: An estimator of dynamic range for intensive perceptual continua

The dynamic range (DR) of a sensory system is the span (usually given in log units) from the lowest to highest intensities over which a continuously graded response is evoked, and may be a distinctive feature of each such system. Teghtsoonian (1971) proposed that, although DR varies widely over sensory systems, itssubjective size (SDR) is invariant. Assuming the psychophysical power law, the exponent for any continuum is given by the ratio of subjective span to DR, both quantities expressed logarithmically. Thus, exponents are inversely related to DR and may be interpreted as indexes of it. Because DR can be difficult or even dangerous to measure directly, we sought to define a smaller range representing some fixed proportion of DR that could be used in its place to test the hypothesis of an invariant subjective range. Observers manipulated the intensities of five target continua to produce the broadest range they found acceptable and reasonably comfortable, a range of acceptable stimulus intensities (RASIN). Combined with an assumed constant SDR (derived from previous research), RASINs accurately predicted exponents obtained by magnitude production from the same observers on the five continua, as well as exponents reported in the literature.     

A portable system for studying head movements in infants in relation to contingent and noncontingent sensory stimulation

A portable apparatus for studying infant head movements and programming sensory stimulation is described. Remote pushbuttons allow observation of vocalizations, smiles, and visual attention. Lightweight and compact, the system allows recording of data in a variety of locations, including home, hospital, and laboratory.     

CROSS-AGE TUTORING: FIFTH GRADERS AS ARITHMETIC TUTORS FOR KINDERGARTEN CHILDREN1

Five fifth-grade students tutored five kindergarten children in basic arithmetic skills for 7.5 weeks. A control group consisted of five kindergarten children who received no tutoring and were matched with the experimental group in arithmetic ability. Pre-, mid-, and posttesting was done using a skills-based arithmetic test. Results showed that the experimental group made far greater gains than the control group on a post-test comparison (matched pairs signed ranks test p = 0.062). In addition, a subanalysis of specific arithmetic skills showed they were improved only when tutoring for that skill was carried out. Systematic observations made of the tutor-student interactions indicated wide tutor-to-tutor variability in the percentage of student responses praised, and very little use of negative, disapproving statements. It was concluded that trained fifth-grade students can effectively teach basic arithmetic skills to kindergarteners.     

FACTORS RELATED TO SUCCESS IN AN MDTA PROGRAM

A study was undertaken to attempt to relate selected defined factors to success in a Manpower Development Training Center program. Subjects were disadvantaged or culturally deprived adults who were referred to a nurse aide-orderly training course that consisted of both vocational and remedial education phases. Factors studied were an evaluation by the referring counselor in the stated interest of an individual taking the training, previous employment history (compiled by both type and duration), formal educational level, age when completing the course, expressed attitudes toward the course while enrolled, and aptitude test results.     

Shifts in categorization and identifiability of visual stimuli by rhesus monkeys

Four monkeys, trained to match to sample, were asked to judge seven stimuli which differed in lightness, in terms of five response categories. The sample stimulus was presented on a black or white background, and all responses were made on a gray background. The mean judgment category for a stimulus was a function of the adaptation reflectance, and, in general, the ease of categorization depended upon the distance of the stimulus from the adaptation level.