Shaw’s stored information as a quantitative measure of sequential structure

In this paper, we describe a method to study the sequential structure in interevent times. The technique uses the stored information of an iterative map developed by-Shaw (1984). The stored information is a quantitative measure of the sequential organization or predictability in data. This paper discusses the concept of stored information and provides a FORTRAN routineto compute the stored information of interevent time data. Several synthetic data sets with known sequential structures are examined. Finally, we present some initial results from computing the stored information of experimental interresponse time data.     

Application of chaos theory to biology and medicine

The application of “chaos theory” to the physical and chemical sciences has resolved some long-standing problems, such as how to calculate a turbulent event in fluid dynamics or how to quantify the pathway of a molecule during Brownian motion. Biology and medicine also have unresolved problems, such as how to predict the occurrence of lethal arrhythmias or epileptic seizures. The quantification of a chaotic system, such as the nervous system, can occur by calculating the correlation dimension (D2) of a sample of the data that the system generates. For biological systems, the point correlation dimension (PD2) has an advantage in that it does not presume stationarity of the data, as the D2 algorithm must, and thus can track the transient non-stationarities that occur when the systems changes state. Such non-stationarities arise during normal functioning (e.g., during an event-related potential) or in pathology (e.g., in epilepsy or cardiac arrhythmogenesis). When stochastic analyses, such as the standard deviation or power spectrum, are performed on the same data they often have a reduced sensitivity and specifity compared to the dimensional measures. For example, a reduced standard deviation of heartbeat intervals can predict increased mortality in a group of cardiac subjects, each of which has a reduced standard deviation, but it cannot specify which individuals will or will not manifest lethal arrhythmogenesis; in contrast, the PD2 of the very same data can specify which patients will manifest sudden death. The explanation for the greater sensitivity and specificity of the dimensional measures is that they aredeterministic, and thus are moreaccurate in quantifying the time-series. This accuracy appears to be significant in detecting pathology in biological systems, and thus the use of deterministic measures may lead to breakthroughs in the diagnosis and treatment of some medical disorders.     

Interpolation in structure from motion

We investigated surface interpolation in displays of structure from motion (SFM). To do so, we introduced a new method for measuring surface perception in dynamic displays—theSFM probe. An SFM probe is a dot that moves rigidly with the dots on a simulated surface, and whose distance from that surface can be adjusted with a joystick or similar control. The displays we studied were random-dot cylinders containing a vertical strip devoid of feature points (thegap). Subjects adjusted an SFM probe, presented in the gap, until the probe dot appeared to be on the surface. Variability in probe-dot placement decreased with increasing texture density on the cylinder and increased with increasing gap width. Subjects showed a consistent bias to place the probe dot outside the cylinder. This bias increased with increasing texture density for the SFM displays. (The opposite bias was found in a static two-dimensional interpolation task with an arc whose curvature matched that of the cylinder: Subjects placed the probe dot inside the arc.) This outside bias is inconsistent with several theoretical approaches to surface interpolation.     

Creating new memories that are quickly accessed and confidently held

In two experiments involving a total of 542 subjects, a series of slides depicting a burglary was shown. After the initial event, subjects were exposed to one or more narratives about the event that contained some misinformation or neutral information about four critical details. Finally, subjects were tested on their memories of what they saw, and their reaction times and confidence levels were measured. When subjects took a standard test in which the misinformation item was a possible response option, they responded very quickly and confidently when making this incorrect choice. Misled subjects responded as quickly and confidently to these "unreal" memories as they did to their genuine memories. It does not seem, then, that the misinformation effect arises from a large proportion of subjects who must resolve a conflict between two memories when they are tested, a conflict that would be expected to take time. When subjects took a modified test in which the misinformation item was not a possible response, misled subjects were as accurate as were controls, but they responded more slowly, regardless of whether they ultimately chose the right or wrong option. These findings indicate that misinformation does introduce some form of interference not detected by a simple test of accuracy.     

Attention deficit disorder with hyperactivity and methylphenidate: The effects of dose and mastery level on children's learning performance

This investigation examined the relationship between methylphenidate (MPH) and the learning and recall of paired associations by children with attention deficit disorder with hyperactivity (ADDH). Forty-five children with ADDH were randomly assigned to one of three groups (novel, partial mastery, and mastery learning) that varied in the amount of previous learning of paired associations and participated in a double-blind, placebo-control, repeated-measures-across-dose (crossover) design. Each child received four doses of MPH (5 mg, 10 mg, 15 mg, and 20 mg) and a placebo in a random, counterbalanced sequence. The results indicated that both the rate of acquisition and accuracy in learning paired associations were significantly, but differentially, affected by MPH dose and the degree of learning mastery. The implications of these results for psychopharmacological research and the monitoring of psychostimulant effects on children's learning performance in academic settings are discussed.The authors wish to acknowledge and express their sincere appreciation to the graduate and undergraduate student members of the Children's Learning Clinic.     

Altering memory through recall: The effects of cue-guided retrieval processing

Three experiments were designed to investigate the influence of initial recall on memory by assessing delayed recall after different immediate cued-recall tests. In all experiments, subjects performed semantic and phonemic encoding tasks on a word list. The subjects then received a cued-recall test that cued the target using the same word as the context word in the encoding task, a test that cued the target with a word from the same level at which the target was encoded, a test that cued the target with a cue from a different level at which the target was encoded, or no immediate-recall test. One day later, the subjects performed a final cued-recall test in which the type of cue (semantic or phonemic) was varied. Consistently, delayed recall was facilitated primarily when the cue on the immediate test was from the same level as the cue on the delayed test. This pattern of facilitation suggests that immediate cued-recall produces an elaboration of an existing memory representation that is closely tied to the type of cue used on the immediate test.     

Parts of visual objects: an experimental test of the minima rule

Three experiments were conducted to test Hoffman and Richards's (1984) hypothesis that, for purposes of visual recognition, the human visual system divides three-dimensional shapes into parts at negative minima of curvature. In the first two experiments, subjects observed a simulated object (surface of revolution) rotating about a vertical axis, followed by a display of four alternative parts. They were asked to select a part that was from the object. Two of the four parts were divided at negative minima of curvature and two at positive maxima. When both a minima part and a maxima part from the object were presented on each trial (experiment 1), most of the correct responses were minima parts (101 versus 55). When only one part from the object--either a minima part or a maxima part--was shown on each trial (experiment 2), accuracy on trials with correct minima parts and correct maxima parts did not differ significantly. However, some subjects indicated that they reversed figure and ground, thereby changing maxima parts into minima parts. In experiment 3, subjects marked apparent part boundaries. 81% of these marks indicated minima parts, 10% of the marks indicated maxima parts, and 9% of the marks were at other positions. These results provide converging evidence, from two different methods, which supports Hoffman and Richard's minima rule.     

Teaching self-treatment of cold symptoms to an anoxic brain injured adult

Traumatic brain injury can result in behavioral and physical deficits that require intensive post-acute residential rehabilitation. Behaviors targeted by such programs include basic self-care and living skills. We examined the efficacy of a behavioral training strategy to teach appropriate medical treatment of four different groups of simulated cold symptoms to an anoxic brain injured adult. The strategy included instructor prompting and feedback in the use of written task analyses and picture cues as self-administered prompts. Subsequent to baseline, the participant used written generic task analyses combined with picture cues and then, if necessary, written specific task analyses combined with picture cues to prompt appropriate self-treatment of the four types of colds. Written individualized task analyses, tailored to participant errors, were used to fade specific task analysis prompts and transfer stimulus control to the discriminative stimuli present in the picture cues. A multiple baseline design across responses showed that skill acquisition did not occur after generic task analysis training, but did so after specific task analysis training. The participant responded to all four types of colds for three consecutive trials at 100% correct under baseline conditions. Follow-up results indicated that transfer of stimulus control to the cold symptoms simulated by the picture cues alone did not maintain over time. Correct responding was retrained using generic and, if necessary, individualized task analysis training conditions.     

The effects of staff self-management on positive social interactions in a group home setting

The purpose of this study was to evaluate the effectiveness of a participative management (self-management) procedure directed toward increasing the frequency of positive interactions between direct-care staff and group home residents. A component of the self-management procedure, goal setting, was also evaluated. This study took place in two group homes housing a total of 16 male and female adults with moderate to mild mental retardation. Ten direct-care staff served as subjects. It was found that self-management produced an increase in the frequency of positive interactions of staff and residents, but did not produce changes in other behaviors being measured (e.g., negative interactions, self-stimulation, etc.). Goal setting did not result in changes in positive interactions or other target behaviors. Reasons for the different results of self-management versus goal-setting are discussed and further research is suggested.     

The Role of Sympathy and Altruistic Personality Traits in Helping: A Reexamination

The purposes of this study were (a) to examine the role of social evaluative concerns in the self-report of sympathy and in the relation of sympathy to helping; and (b) to determine the role of "altruistic personality" traits and situationally induced vicarious emotional responses in the intention to help. Dispositional and situational self-reports of sympathy and other vicarious emotional reactions were obtained for persons who also were given the opportunity to assist a needy other. Moreover, dispositional measures of concern with social evaluation and an altruistic orientation were obtained, and a bogus pipeline manipulation was instituted for half the study participants. Both dispositional and situational self-reported sympathy were positively related to helping, as were other personality indices viewed as reflecting altruistic characteristics. The relations for the dispositional indices of sympathy were not due solely to social evaluative concerns or to other egoistic concerns. The effects on intended helping of dispositional sympathy, perspective taking, and the tendency to ascribe responsibility for others to the self appeared to be both direct and mediated by situational sympathetic responding. Finally, situational sadness did not mediate the effects of sympathetic responsiveness.