Decision processes in visual discrimination of line orientation

The contribution of decision factors to the meridional variations in line orientation discrimination was determined for two-alternative forced-choice experimental designs. Using Johnson's (1980) formalization of decision processes in discrimination tasks, we identified three decision factors: the decision rule, memory variance, and criterial noise. In a first experiment, we showed the effect of experimental design on orientation discrimination to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in orientation discrimination were not due to a decision rule anisotropy. In a second experiment, the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. The results of two other experiments supported the hypothesis that the meridional variations in orientation discrimination are not due to a criterial noise anisotropy. These different results strongly suggested that the oblique effect in line orientation discrimination is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in line orientation discrimination.     

Disruption of reference in aging

A homogeneous sample of normal adults living in a religious order in a study of age effects on reference as a cohesive device in discourse production and comprehension. Narrative and procedural discourse were examined across various levels of complexity and stimulus/response requirements. Results indicate that significant ambiguity of reference emerges in the younger elderly group (age 64-76) in comparison to the middle-aged group (age 27 to 55), and increases markedly in the older elderly group (age 77-92). Related impairments of comprehension and cognition were also observed. These findings are interpreted to be general features of linguistic variation with advancing age. Communicative consequences of ambiguous reference are discussed.     

Lateralization of lexical codes in auditory word recognition

Three experiments examined the lateralization of lexical codes in auditory word recognition. In Experiment 1 a word rhyming with a binaurally presented cue word was detected faster when the cue and target were spelled similarly than when they were spelled differently. This orthography effect was larger when the target was presented to the right ear than when it was presented to the left ear. Experiment 2 replicated the interaction between ear of presentation and orthography effect when the cue and target were spoken in different voices. In Experiment 3, subjects made lexical decisions to pairs of stimuli presented to the left or the right ear. Lexical decision times and the amount of facilitation which obtained when the target stimuli were semantically related words did not differ as a function of ear of presentation. The results suggest that the semantic, phonological, and orthographic codes for a word are represented in each hemisphere; however, orthographic and phonological representations are integrated only in the left hemisphere.     

The Rotter locus of control scale: The comparison of alternative response formats and implications for reliability, validity, and dimensionality

Participants completed the Rotter internal/external (IE) instrument using three different response formats before and after completion of the Outward Bound program, and were evaluated by external observers at the end of the intervention. Multitrait-multimethod analyses indicated that five specific IE facets identified in previous research were consistently distinguished with each of the response formats. While responses were substantially more internal after the intervention, effect sizes varied with the IE facet and with the response format. Observer responses were significantly correlated with self-responses, and provided additional support for the construct validity of responses to the Rotter instrument and the interpretation of the intervention effect. Nevertheless, problems with the Rotter instrument were identified, and the implications for further research were discussed.     

Range effects in successive discrimination

In two sets of experiments we examined pigeons' discrimination performance with a visual flicker-rate continuum, using a conventional successive discrimination procedure. In the first experiment, responses during the intermediate stimulus value were never reinforced, while responses during stimuli on either end of the continuum were reinforced periodically. In the second experiment, responses during stimuli from one end of the continuum were never reinforced, while responses during stimuli from the other end of the continuum were reinforced periodically. Results from both experiments show that discrimination between unchanged positive and negative stimulus values is a function of the range over which the total stimulus set varies. These range effects are comparable to effects found in absolute judgment tasks in human and animal psychophysics. In addition, the range effects reported here are not due to channel capacity, but may depend instead on variability in judgment criteria.     

The Zeigarnik effect and intrinsic motivation: Are they the same?

The present study focused on delineating the parameters under which intrinsic motivation leads an individual to reengage an activity from those that result in the Zeigarnik effect. In a posttask free-choice period, participants not completing the experimental task displayed more reengagement behavior than participants completing the task (the Zeigarnik effect). When participants were also provided self-efficacious performance feedback via a prearranged competitive outcome manipulation, there was no evidence of the Zeigarnik effect, while there was support for intrinsic motivation from competent self-efficacious performance feedback. Results were discussed in terms of distinguishing between intrinsic motivation and the Zeigarnik effect as sources of reengagement motivation. It was concluded that, in the presence of self-efficacious performance feedback, the competent-incompetent impression was more salient than task-completion feedback.Preparation of this article was supported by Texas Christian University grant TCU/RF 5-23757.     

Type A behavior,anger expression,and reactions to anger imagery

The experiment investigated the effects of Type A behavior, anger expression, and gender on perceptions of control and heart rate. Jenkins Activity Survey defined Type A and B subjects, categorized as either high or low in anger expression, were asked to recall, image, and generate self-referent statements about angry situations. State anger and heart rate were measured during all of the anger induction conditions, and ratings of imagery vividness and perceptions of control for self and others were taken following the recalled and imaged anger conditions. The results, with both the heart rate and self-report measures, indicated that the effects of the independent variables were interactive and situationally dependent. Type A behavior was associated with increased heart rate in two experimental conditions (mood anger and recalled anger), and, in one instance, this effect was amplified in male subjects (recalled anger). The self-report results yielded interactional effects that most commonly took the form of high anger expression, with male Type A's providing higher ratings of state anger, more vivid anger imagery, and lower perceived self-control ratings than did other categories of subjects. Taken together, these results suggest that anger expressiveness, particularly among males, amplifies the usual reactions attributed to Type A's, and that such effects are mediated by the threat of loss of control. Further, the observed interactive relationships limit the generalizability of A/B differences and raise definitional questions about Type A behavior.     

Weanlings' transfer of conditioned ethanol aversion from olfaction to ingestion depends on the unconditioned stimulus

Weanling (21-day-old) rats were exposed to an alcohol odor paired with either an interoceptive (apomorphine-induced illness) or exteroceptive (footshock-induced distress) reinforcer. Twenty-four hours later, ethanol preferences were measured in a locational olfactory test (ethanol vs lemon odor) or an ingestion test (5.6% v/v ethanol vs 0.25% v/v citric acid solution). Weanling rats expressed substantial olfactory aversions, independent of the reinforcer employed in conditioning. During the drinking test, however, only rats that had experienced the ethanol odor paired with internal malaise showed a significant reduction in the intake of the ethanol solution when compared to unpaired controls. Furthermore, rats that had experienced the ethanol odor paired with external distress drank significantly more of the ethanol solution than their controls. These results provide further evidence that olfactory experiences with ethanol can lead to changes in ethanol ingestion, and indicate that the nature of the unconditioned stimulus is critical in establishing the ingestive effect.     

Preserved spatial memory in old rats survives 10 months without training

Aged rats with extensive prior training on the radial maze retain the capacity for accurate spatial working memory (WM) for at least 3 months without practice. To investigate the temporal limits of this influence of prior experience we compared the reacquisition of spatial WM by a group of experienced 21.5-month-old rats to the original acquisition by naive 3-month-old rats. The aged rats had received 225 radial maze tests between 3 and 11 months of age. Despite 10 months without practice the old rats rapidly reacquired critical performance. Their reacquisition was markedly superior to original learning by the young rats, even when delays as long as 5 h were imposed between the rats' fourth and fifth choices during the daily tests in the eight-arm maze. Additional tests showed that neither young nor old rats employed a response strategy to maintain accurate spatial WM performance. Experience clearly confers long-lived protection against the otherwise deleterious effects of aging on spatial WM, but the mechanism by which this influence arises is unknown.