Age-dependent facilitation of taste-footshock conditioning by prior exposure to the training context

Among adult rats, gustatory stimuli are easily associated with illness, but not with external unconditioned stimuli such as footshock. Recent evidence indicates, however, that this cue-to-consequence specificity may vary ontongenetically. The present studies examined the acquisition of an aversion to a taste paired with footshock in 5- and 15-day-old rats. Consistent with previous reports, 5-day-old rats avoided the taste that preceded footshock, while 15-day-old subjects did not express an aversion to the taste paired with footshock. Exposure to the training context for either 1 or 5 h prior to conditioning disrupted taste-footshock conditioning in the 5-day-old subjects. For the 15-day-old subjects, 1 h of pre-conditioning exposure to the training context had no effect on conditioning, whereas a longer duration of preexposure promoted conditioning to the taste cue. The results suggest ontogenetic differences in stimulus selection.     

The naturalistic fallacy: moral inferences drawn from research with children versus adults

The naturalistic fallacy occurs when a person reads a report of scientific research and concludes that the moral implication of the research was included in the article when, in fact, it was not. For example, the fallacy is committed when a study contains the conclusion that TV advertising increases preference for sugar-based foods, but the reader later believes that the study concluded that TV advertising should be controlled. Previous research indicates that the commission of the fallacy was strong when memory for social research was tested. The present study showed that the commission of the fallacy was stronger when the research which was read involved children as subjects compared to adult subjects. Increased empathy for the subjects of a research article strengthens commission of the fallacy.     

Clinical judgment, clinical training, and professional experience

Reviews studies on training, experience, and clinical judgment. The results on the validity of judgments generally fail to support the value of on-the-job experience in mental health fields. The validity results do provide limited support for the value of training. Other results suggest that experienced clinicians are better than less experienced judges at knowing which of their judgments are likely to be correct and which are likely to be wrong. Reasons why clinicians have trouble learning from experience are given. Recommendations are made for improving training and clinical practice.     

Extraretinal information about eye position during involuntary eye movement: optokinetic afternystagmus

Despite importance for theories of perception, controversy exists as to whether information is available to the perceptual system about involuntary as well as voluntary eye movements. We measured the perceived direction of targets flashed briefly in an otherwise dark field during the primary phase of optokinetic afternystagmus (OKAN), an involuntary eye movement that persists in darkness following optokinetic stimulation. Perceived direction was measured by unseen pointing in one experiment and by pointing made under visual control in a second experiment. Pointing was essentially veridical in both experiments, indicating that accurate extra-retinal information about eye position (presumably, as efference copy) exists for OKAN. Illusory motion of visual targets, which can occur during involuntary oculomotor responses, therefore cannot be attributed to a lack of efference-copy signals for such eye movements.     

Relationship between two nontraditional procedures for assessing speech-sound discrimination

Test of speech-sound discrimination are used by special educators, reading specialists and speech-language pathologists in assessing children's ability to differentiate between speech sounds occurring in standard English. Such tests are important in determining if speech-sound articulation errors are caused by difficulty in making such differentiations. However, during the past 10 years, these tests have been criticized on the basis of their reliability and validity. The purpose of this study was to examine the use of two alternative methods of assessing speech-sound discrimination with a school-aged population to determine if they elicited responses in a similar manner.     

H-reflexes during a motor skill acquisition task

H-reflex amplitudes were studied during the acquisition of a motor skill involving coordinated isometric plantarflexion at the ankle joints as subjects learned to trace a triangular pattern on an oscilloscope screen by controlling plantarflexion torque applied against load cells. Torque feedback was presented on a subject oscilloscope with the right foot controlling a vertical cursor and the left foot a horizontal cursor. Eleven subjects reached criterion performance. H-reflexes were recorded from the right soleus and timed to the initiation of soleus muscle activity to plantarflex the foot. Average time to complete one trial decreased from 9 sec. in the prelearning block to 4 sec. postlearning. No single learning strategy was evident as subjects varied widely in their levels of H-reflex amplitude, but during postlearning, H-reflex amplitude became consistent within subjects as tracing performance became faster and accurate.     

Pitch motion with random chord sequences

Perception of global pitch motion was studied through psychoacoustic experiments with random chord sequences. Chords contained either six or eight (fixed) tone elements, being sinusoidal, sawtooth-like, or Shepard tones, which were either on or off according to a probability controlled by the experimenter. Sequences of 2, 4, 5, or 8 chords were used. Identification by subjects of the perceived direction of overall pitch motion (up or down) was found to be well accounted for by a model in which the ultimate pitch motion percept is given by a sum of contributions from selected element transitions--that is, transitions between adjoining tone elements in successive time frames only. In its simplest form, this dipole contribution model has only one free parameter, the perceptual noise for an element transition, which was estimated for various acoustic tone representations and chord arrangements. Results of two experiments, which were carried out independently in two different laboratories, are reported.     

Interference in localizing tactile stimuli

A series of experiments investigated the ability of subjects to localize a tactile stimulus in the presence of an additional, extraneous tactile stimulus. The subject's task was to localize a tactile stimulus (target) presented at one of several locations on his or her left index fingerpad. The target stimulus, generated on a 6 x 24 array of stimulators, was presented either by itself or in the presence of an extraneous stimulus (masker) that either preceded or followed the target. The localizability of the target was affected by the temporal separation between the target and masker in much the same way as previous studies have shown identification of tactile patterns to be affected. Unlike previous identification results, presenting the masking stimulus to the same location as the target interfered with localizability, although not as much as did presenting the masker to a different location. The results are discussed in terms of their implications for identification and discrimination of tactile patterns.