Infants' responsiveness to the auditory and visual attributes of a sounding/moving stimulus.

Responses to unimodal and multimodal attributes of a compound auditory/visual stimulus were investigated in 4-, 6-, 8-, and 10-month-old infants. First, infants were habituated to a compound stimulus consisting of a visual stimulus that moved up and down on a video monitor and a sound that occurred each time the visual stimulus reversed direction at the bottom. Once each infant met a habituation criterion, a series of test trials was administered to assess responsiveness to the components of the compound stimulus. Response was defined as the total duration of visual fixation in each trial. In the two unimodal test trials, the rate at which the component was presented was changed while the rate of the other component remained the same, whereas in the bimodal test trial the rate of both components was changed simultaneously. Results indicated that infants at each age successfully discriminated the bimodal and the two unimodal changes and that regression to the mean did not account for the results. Results also showed that disruption of the temporal relationship that accompanied the change in rate in the two unimodal test trials was also discriminable, but rate changes appeared to play a greater role in responsiveness than did synchrony changes. Considered together with results from similar prior studies, the current results are consistent with the modality appropriateness hypothesis in showing that discrimination of temporal changes in the auditory and visual modalities is dependent on the specialization of the sensory modalities.     

Spatial attention in Ponzo-like patterns.

A variant of Ponzo's pattern was devised by drawing converging oblique lines at the ends of each of two horizontal lines that were located directly one above the other. Pairs of converging or diverging fins (either between or outside the horizontal shafts) were systematically removed. The results showed that, as predicted by integrative field theory, oblique lines between the shafts produced more distortion than did oblique lines outside the shafts. Also, it was shown that the attentive field construct in integrative field theory was crucial for predicting patterns of means and variances in this experiment. The modified Ponzo effect was shown to have much in common with the classical Müller-Lyer illusion. The subtle differences between the two were explained by proposing that the size of the optimum attentive field was larger in the Ponzo tasks than in the Müller-Lyer tasks because expansion fins are found on both shafts in the Ponzo-like figure.     

Adaptation to auditory motion in the horizontal plane: effect of prior exposure to motion on motion detectability.

Thresholds for auditory motion detectability were measured in a darkened anechoic chamber while subjects were adapted to horizontally moving sound sources of various velocities. All stimuli were 500-Hz lowpass noises presented at a level of 55 dBA. The threshold measure employed was the minimum audible movement angle (MAMA)--that is, the minimum angle a horizontally moving sound must traverse to be just discriminable from a stationary sound. In an adaptive, two-interval forced-choice procedure, trials occurred every 2-5 sec (Experiment 1) or every 10-12 sec (Experiment 2). Intertrial time was "filled" with exposure to the adaptor--a stimulus that repeatedly traversed the subject's front hemifield at ear level (distance: 1.7 m) at a constant velocity (-150 degrees/sec to +150 degrees/sec) during a run. Average MAMAs in the control condition, in which the adaptor was stationary (0 degrees/sec,) were 2.4 degrees (Experiment 1) and 3.0 degrees (Experiment 2). Three out of 4 subjects in each experiment showed significantly elevated MAMAs (by up to 60%), with some adaptors relative to the control condition. However, there were large intersubject differences in the shape of the MAMA versus adaptor velocity functions. This loss of sensitivity to motion that most subjects show after exposure to moving signals is probably one component underlying the auditory motion aftereffect (Grantham, 1989), in which judgments of the direction of moving sounds are biased in the direction opposite to that of a previously presented adaptor.     

The effects of complexity on the perception of vibrotactile patterns presented to separate fingers.

Pairs of vibrotactile patterns were presented to subjects' left middle and index fingerpads (unilateral presentation) or left and right index fingerpads (bilateral presentation), using two Optacon arrays. A set of simple (one-line) patterns and a set of complex (two-line) patterns were constructed so that they were equally identifiable when presented individually. In Experiment 1, discrimination performance was lower for two-line patterns than it was for one-line patterns, and it was lower for unilateral presentation than it was for bilateral presentation. Communality, the number of lines that two patterns share in common, was a major factor in reducing discrimination performance for two-line patterns. Subjects' abilities to identify one member of the pair of patterns were measured in Experiment 2. There were no significant differences in performance between pattern sets or type of presentation when subjects attended to a single pattern. However, when subjects were required to attend to both patterns, identification performance was lower for two-line patterns than it was for one-line patterns, and it was lower for unilateral presentation than it was for bilateral presentation. The results suggest that there are limited attentional resources for processing vibrotactile patterns and that more resources are available bilaterally than are available unilaterally.     

Preference can be more powerful than detection of oddity as a test of discriminability.

Subjects presented with sets of three samples, two of distilled water and one of tap water, were significantly more consistent in choosing the tap water as preferable than they were in identifying it as the odd sample in the set. The result is opposite to the prediction of high-threshold models of sensory discrimination, which say that if a difference is not noticed, preferences will be random, whereas if a difference is noticed, preferences may still be in either direction. The result can be quantitatively explained by a model advanced by Frijters to explain an analogous anomaly found with the triangle test used in the food industry. Applying his model to the observed proportions yields essentially equivalent estimates of sensory difference (d' = 1.5, approximately) from the two tasks, and a direction of preference almost unanimously in favor of the tap water that was used. Since the model predicts that the proportion of subjects choosing the odd item will depart further from chance in the preference task than in the oddity task, the former has greater power to reject the null hypothesis of no sensory difference if one exists and if preference is overwhelmingly in one direction.     

Categorical time production: evidence for discrete timing in motor control.

Subjects performed a repetitive manual tapping task, attempting to match a given rate of auditory stimulus pulses, first with the pulses audible (synchronization) and then with the pulses turned off (continuation). In different sessions, the interstimulus interval (ISI) was selected from the range 175 to 825 msec in steps of 25 msec, with different ISI values presented in a random order. Across this range of ISI conditions, interresponse intervals (IRIs) exhibited alternating positive bias (too slow) and negative bias (too fast). We interpret this pattern of bias in terms of a discrete, or categorical, timing mechanism in motor timing. Categorical time production can be viewed as extending our conception of the timekeeper in Wing's (Wing & Kristofferson, 1973a, 1973b) two-process model of motor timing and may be related to the system of multiple clocks proposed by Kristofferson (1980) to explain a categorical pattern of variability measures in duration discrimination.     

Time-place learning by pigeons, Columba livia

In each of two experiments, 2 pigeons received discrimination training in which food reinforcement for key pecking was conditional upon both spatial and temporal cues. In Experiment 1, food was available for periods of 30 s at each of three locations (pecking keys) during trials that lasted 90 s. In Experiment 2, food was available for periods of 15 min at each of four locations (pecking keys) during a 60-min trial. In both experiments, pigeons' key pecking was jointly controlled by the spatial and temporal cues. These data, and other recent experiments, suggest that animals learn relationships between temporal and spatial cues that predict stable patterns of food availability.     

Towards a postmodern ethics: Sir Isaiah Berlin and John Caputo

Conclusions It may seem to their opponents that they are trying to have their cake and eat it too. Postmodernists admit that their own paradigm must be and will be placed into question by future thinkers. But if they can anticipate an eventual reaffirmation of their paradoxical stand in an ongoing oscillating debate, then cannot it be said that they have arrived at a truth that transcends their time and place in history? And, if so, is not their fallibilist stance in fact self-referentially inconsistent? The response of postmodernists is the claim that each reaffirmation of a fallibilist epistemology and ethics throughout history is in fact sui generis. And this is the case because each reaffirmation has its own unique context within which it is made. Modernists will of course argue that these contextual differences are nonessential and irrelevant. And the debate over the problem of the One and the Many is once again launched in a new context. Thus far from running away from the paradoxical position that what they assert is both true and false, postmodernists revel in such inconsistencies.But does not such an ethical stance resemble the Sisyphean nightmare of being condemned to roll a heavy stone up a cliff only to have it keep falling back to the bottom ad infinitum? If no decision is innocent of doing some harm in the world, why should we bother to play the moral game at all? Indeed, what possible help is a postmodernist ethics when it comes to making some of the complex and crucial decisions we face today if it refuses to say anything substantial beyond the recommendations that we be cautious and balanced?And the postmodernist can only reply that we are letting our neurotic need for solid foundations frighten us. For ethics is an art not a science. There are no absolute rules. If we do not like the way the game is set up, then we are simply revealing our ultimate hubris in the face of a mystery requiring deep humility.     

Erikson's life cycle theory and images of God

Human life is a God-ordained pilgrimage by which persons travel toward ever-expanding images of God that emerge from the universal pattern of developmental crises. Using the work of Erik Erikson on the human life cycle and the work of Donald Capps on human sin, the author presents a way to conduct pastoral diagnosis and to provide pastoral care. By accurately tracing a person's images of God back to their potentially unresolved developmental crises, the pastoral caregiver can reopen opportunities for further and healthier resolution of the crises.