Serial position and clustering effects in a chimpanzee’s “flee recall”

Lana, a chimpanzee sophisticated in the language Yerkish, was tested for free recall on lists consisting of from one to eight words randomly drawn from one of three taxonomic categories or on lists consisting of nine words with every third word from a different category. Serial position effects were observed for the four- to eight-item lists, with statistically significant first-item primacy effects on the seven- and eight-word lists and last~position recency effects on the six-, seven-, and eight-word lists. Also, above-chance clustering was observed in the recall of the nine-item categorized lists. These results were compared and contrasted with the serial position and clustering effects obtained in free recall with humans. Several alternative theoretical accounts of the results were considered.     

Processing level and recognition: A search method for inducing alternative encodings of unrelated words

Twenty-four subjects viewed cards containing four words. In synonym orienting, half of the cards contained a synonym pair and half did not; in homophone orienting, half of the displays contained a homophone pair. The remaining two words in each display were used to index retention. During presentation of displays, subjects responded “yes” or “no” to indicate the presence or absence of a matching pair. Following presentation, a recognition test was administered. Half the items were tested early and half were tested late; within each test order, half the items appeared with context cues during testing and half appeared without. Results showed superior recognition (1) following semantic orienting, (2) for items tested early, (3) for items tested with context, and (4) for nonmatch displays requiring exhaustive item comparison. An Orienting by Test Cuing interaction showed that the presence of test cues improved recognition for homophone orienting items only. The interaction may have resulted from the lack of cuetarget associations and the reinstatement of the phonemic orienting set during the test.     

Case-like categories in children: The actor and some related categories

Case categories were investigated using a method in which pictures are presented accompanied by a sentence describing the scene: Preschool children learn to put tokens on the objects in the pictures according to the role each object plays in the scene as described. Generalization trials explore what the children include within the various roles. Children rapidly learn to associate tokens with case-like categories during the training phase, and readily transfer to new stimuli in generalization trials. The experiments demonstrate that children have a broad Actor category. The Actor “does” the action, and Actors are not necessarily animate. However, animacy is a class property of stimuli to which the children were very sensitive. There was evidence that User and Instrument are subcategories of Actor that are differentiated only when a sentence contains both. The data also suggest a Locative category, and Patient as a category of the grammatical object. Finally, the children appeared to treat subjects of predicate adjectives as a separate category, here called the Subject of Attribution, distinct from Actor, and functionally independent of objects of transitive verbs.     

Letter versus dot stimuli as tools for “splitting the normal brain with reaction time”

Filbey and Gazzaniga (1969) found simple dot-present or -absent reports averaged 35 ms slower for the left than for the right visual field. Other data suggests that verbal processing efficiency differences between the cerebral hemispheres, rather than transcallosal transfer time alone, must be tapped to obtain half-field differences as large as 35 ms. Three experiments were conducted. The first failed to show any half-field differences in vocal RT for dot detection; the second replicated previous reports of significant right field superiority of vocal RT to letter stimuli for right handers, and also showed a substantially smaller half-field difference for left handers; the third experiment, utilizing the fixation control procedure of the second experiment, again failed to show half-field differences for the dot detection paradigm. Differences between the Filbey and Gazzaniga and present results probably reflect important procedural differences. We conclude that transcallosal transfer time for simple dot information is much smaller than assumed by Filbey and Gazzaniga and that the letter report-time task taps hemispheric asymmetries of verbal processing efficiency.     

Cognitive processing of uncertainty: Its effect on pupillary dilation and preference ratings

The prediction of greater pupillary dilation as unpredictability (induced by random-turn shapes) increased was supported (p <.001) in studies involving 40 young adults and 10 children. The postulated linearity of this increase found support, except in cases where apparent stimulus-selection strategies attenuated the dilation at higher levels of variability. Those Ss who did preference ratings concomitantly with the intake of visual unpredictability evidenced significantly greater dilation (p <.001) at the time of reporting the rating. Both children and adults dilated significantly less to the shapes after prolonged experience with similar stimuli. indicating development of either ability to handle variability or to selectively filter input, but age was not a factor. The lack of any significant relationship between pupillary dilation and preference indicated the need for more definitive work in determining when these two indices profitably complement each other. Finally, adults dilated more to provocative auditory stimuli than to the visual shapes.     

Adjunctive brainstem behaviors in the rat

Adjunctive behaviors refers to behaviors that are “out of context” and/or excessive in amount. The terminology was first used for unexplained behaviors associated with food pellet ratio contingencies in food deprived rats (Falk, 1971). Clinically, unrelated and complex excessive behaviors were also noted with brainstem and diencephalic discharges (Andy, 1986, 1989 and 1995; Andy and Jurko, 1986). The objective of this study was to develop a model of brainstem generated adjunctive behaviors in the rat. Method: Sixty-one adult rats were used. Kindling was induced by mechanical and DC electrical perturbations in the midbrain. Nine different treatment groups were established in which lesions and drugs were used separately and in different combinations. Cocaine was used to accentuate, and dextrorphan to attenuate the kindling process. Behaviors were visually analyzed and recorded by video camera; they were not quantified. DC stimulation and EEGs were done with Grass instruments. Recording and stimulation sights were verified histologically. Results: A total of 45 different behaviors were elicited. DC stimulation kindled subjects had significantly more behaviors than did electrode insertion alone and cocaine alone. However, cocaine combined with DC stimulation increased the number and intensity of the kindled behaviors. Dextrorphan tended to facilitate catatonic and sleep states. Behaviors occurred randomly and were unrelated, even when they occurred in clusters. The behaviors were associated with four abnormal EEG discharge patterns. Conclusion: We speculate that brainstem behaviors are innate adjunctive drives that are generated in the brainstem reticular formation. They are monitored by the cortex and partially modified by environmental and cortical inputs.     

‘Attentional Bias’ in correlation judgments? Smedslund (1963) revisited

Smedslund (1963) reports one of the first studies that investigated human judgments of correlation. Smedslund's conclusion, that people reason about correlation mostly from a consideration of the number of times two variables co-occur, has become textbook wisdom (e.g. Baron's "attentional bias", 1994). Yet the data reported in Smedslund's paper fall short of endorsing such a conclusion. After reviewing the original paper, we present the method with which we replicated Smedslund's main experiment. In Experiment 1 subjects were presented with symptom-disease correlation data through a simulated medical diagnosis task. Subjects clearly discriminated between data sets which shared an equal number of symptom-disease co-occurrences but which otherwise showed different levels of correlation. Subjects' diagnoses showed a propensity to predict the disease in the presence of the symptom, and symptom-disease co-occurrences were overestimated in two of the five data sets presented to the subjects. Experiment 2 used a novel abstract scenario with a symmetric predictor variable. Judgments again indicated good discrimination, and biases in prediction responses and case recall were eliminated. In both experiments, judgments of zero correlation were a function of the outcome base rate. We evaluate and contrast the extent to which Cheng's (1997) model of causal induction and two associative models, Rescorla and Wagner (1972) and Pearce (1987) can anticipate the observed pattern in the mean judgments.     

Revision and Restandardization of the Conners Teacher Rating Scale (CTRS-R): Factor Structure, Reliability, and Criterion Validity

The Conners Teacher Rating Scale (CTRS) is a commonly used research and clinical tool for assessing children's behavior in the classroom. The present study introduces the revised CTRS (CTRS-R) which improves on the original CTRS by (1) establishing normative data from a large, representative North American sample, (2) deriving a factor structure using advanced statistical techniques, and (3) updating the item content to reflect current conceptualizations of childhood disorders. Using confirmatory factor analysis, a six-factor structure was found which includes Hyperactivity-Impulsivity, Perfectionism, Inattention/Cognitive Problems, Social Problems, Oppositionality, and Anxious/Shy factors. The reliability of the scale, as measured by test-retest correlations and internal consistency, is generally satisfactory. Using all of the scale factors to discriminate between attention deficit hyperactivity disordered and normal children, 85 percent of children were correctly classified, supporting the validity of the scale and indicating excellent clinical utility. Similarities and differences between the original CTRS factor structure and the CTRS-R factor structure are discussed.