Discrimination of 3-D shape and 3-D curvature from motion in active vision

We examined the ability of human observers to discriminate between different 3-D quadratic surfaces defined by motion, and with head position fed back to the stimulus to provide an up-to-date dynamical perspective view. We tested whether 3-D shape or 3-D curvature would affect discrimination performance. It appeared that discrimination of 3-D quadratic shape clearly depended on shape but not on the amount of curvature. Even when the amount of curvature was randomized, subjects’ performance was not altered. On the other hand, the discrimination of 3-D curvature clearly depended linearly on curvature with Weber fractions of 20% on the average and, to a small degree, on 3-D shape. The experiment shows that observers can easily separate 3-D shape and 3-D curvature, and that Koenderink’s shape index and curvedness provide a convenient way to specify shape. These results warn us against using just any arbitrary 3-D shape in 3-D shape perception tasks and indicate, for example, that emphasizing 3-D shape in computer displays by exaggerating curvature does not have any effect.     

Abnormal and normal obsessions

Three related, exploratory studies were carried out in order to ascertain the occurrence and nature of normal obsessions, and to relate them to abnormal obsessions. The subjects included 8 obsessional patients, and up to 124 non-clinical subjects.Broadly, the findings were that normal obsessions are a common experience and they resemble the form of abnormal obsessions. They also show some notable similarities of content. However normal and abnormal obsessions differ in several respects, including frequency, duration, intensity and consequences, among others.With repeated practice, the frequency, duration and discomfort of obsessions are observed to decrease. Overall, the findings are considered to be consistent with the noxious stimulus cum habituation theory.     

Insulin and glucagon as determinants of body weight set point and microregulation in rats

Seven adult male rats were observed for body weight and microregulation (feeding, drinking, and running patterns) after manipulation of insulin and glucagon levels. They received three injections per day for 3 days each week of 3 U of protamine zinc insulin, .25 mg of zinc glucagon, 50 microgram of protamine zinc somatostatin (SRIF), or protamine zinc vehicle. Diabetes was then induced with an iv injection of streptozotocin (65 mg/kg), and the injection schedule was repeated after the full diabetic syndrome emerged. In all rats whose insulin levels were increased relative to glucagon levels, body weight increased; in those whose glucagon levels were increased relative to insulin levels, body weight decreased. All injections except vehicle reduced meal sizes in both normal and diabetic rats, but only insulin increased the frequency of feeding. These effects could be predicted by the glucostatic theory of food intake regulation and are thus interpreted as supportive of this theory. These results also support the hypothesis that the relative concentration of insulin to glucagon is a regulator of body weight set point.     

Foreign Investments in Southern Africa

“If one believes in the Prince of Peace one must stop committing crimes in the name of the Prince of Peace. The Christian Church still rules this world, it still has the power to change the structure of South Africa.” James Baldwin in his address to the Fourth Assembly of the World Council of Churches, Uppsala, 1968.     

A speech-rate intelligibility threshold for speeded and time-compressed connected speech

An automated threshold method has been developed for determining the maximum rate of speech understood by individual listeners. Two experiments were undertaken to determine whether the threshold was related to the comprehension of speech or to speech intelligibility. The first experiment compared thresholds of two types of rapid speech reportedly different in intelligibility: simple speeded speech and speech compressed by the sampling method. The second experiment sought to determine the relationship of the threshold to traditional comprehension measures. The results are discussed in terms of the intelligibility and comprehensibility of speech.     

Goal attainment scaling: An idiosyncratic method to assess treatment effectiveness in agoraphobia

Goal attainment scaling (GAS) is an individually tailored way to measure treatment gains, using a highly standardized procedure. An advantage of the method is that it takes into account individual characteristics of the patients, and at the same time the data are suitable for quantitative analysis and comparable across patients. Despite the wide acceptance and use of the method in the evaluation of psychotherapy, data on its psychometric properties are rather scarce. In the current study, GAS was used as one of several outcome measures in a research project on the effectiveness of various treatments for panic disorder with agoraphobia. Guidelines for GAS are presented as well as data on the reliability and validity of the procedure. Results indicate that the procedure is reliable, valid, and sensitive to the improvement of patients during treatment. Comparison of GAS with standardized measures revealed considerable concordance, although the clinical end status of patients diverged somewhat dependent on the measure considered.     

Phonological deficits: Beneath the surface of reading-acquisition problems

Summary In Experiment 1, the performance of young retarded readers on speech-segmentation tasks was compared with the performance of normal subjects matched for chronological age (CA) and with subjects matched for reading age (RA). Retarded readers were poorer than both control groups in consonant deletion, while there was no difference between the groups on a rhyme-judgement task and a syllabic-vowel-reproduction task. In Experiment 2, another group of reading retarded children was compared with CA and RA controls on the classification of pseudowords, either by common phoneme or by overall phonetic similarity. The retarded readers made fewer classifications based on common phoneme than both control groups, while there was no difference between the groups in classifications based on overall phonetic similarity. In Experiment 3, adult developmental dyslexics were compared with normal adults in the tasks of Experiments 1 and 2. The dyslexics made fewer classifications based on a common phoneme than the normals, while no difference was found in classifications based on overall phonetic similarity.     

Stop Doubting with Descartes

Did Descartes manage to overcome the skeptics? If we understand “overcome” in the sense of “refute,” the answer is no, since his hyperbolic doubt harbors several blind spots and is, therefore, not as radical as is commonly argued. In this way, the victory of the cogito is perhaps less decisive and fruitful than it is claimed. If we understand “overcome” in the sense of “remove” or “move beyond,” the answer is yes. Descartes has overcome skepticism, but at the cost of a decision, a sort of bet made in favor of reason based on a confidence in the human mind that is never really subverted. This faith in reason, truth, and specific epistemological principles in Descartes’ philosophy constitute what Wittgenstein calls “hinges,” which are indispensable for doubting and searching for truth. In this sense, Descartes’ anti-skepticism is more a confidence in reason in order to save the possibility of science than the result of a logical refutation.

     

Sentence comprehension and production in children with cochlear implants: Errorless procedures and equivalence-based instruction

Research supports equivalence-based instruction (EBI) and matrix training for increased listening and speaking skills in children with cochlear implants (CI). We incorporated errorless procedures to optimize the EBI and evaluated the effects on the auditory comprehension and verbal responding at-sentences level in six CI children who were readers and showed inaccurate tacting. Subject-verb-object sentences were arranged in two matrices; diagonal combinations were trained and evaluated non-diagonal combinations. EBI included stimulus fading and exclusion to directly teach the dictated sentence-picture matching; written-sentences construction upon dictation also was taught. Probes assessed the derived stimulus-stimulus and stimulus-response relations. All participants learned the auditory-visual discriminations and the exclusion resulted in fewer errors than on a stimulus fading procedure. Five participants formed equivalence classes and increased verbal responding to equivalent stimuli, especially pictures tacting. They also showed recombinative generalization for both matrices. Professionals can incorporate errorless procedures to EBI for improving sentence comprehension, tacting, and productivity in CI children.