How is gait visually regulated when the head is travelling faster than the legs?

Gait regulation patterns were examined under various visual conditions in order to determine whether speed information provided by peripheral vision is taken into account in gait adjustments. Nine subjects walking toward a visual target on the ground were required to place one foot exactly on it. peripheral vision was either restricted to a 12 degrees angle or decorrelated, corresponding to a moving speed greater than the actual walking speed. Decorrelation was obtained by placing the subject on a treadmill moving in the walking direction. The results show, by comparison with the control condition, that the restriction of peripheral visual information did not affect the accuracy of the foot positioning, whereas decorrelated conditions affected it significantly: we noted that the gait regulation was triggered early on and showed a very stable pattern so that the distance to the target was consistently underestimated. This suggest that, although visual speed information is not indispensable in this kind of task, it is nevertheless taken into account in stride adjustments when the whole visual field is available. The results are discussed, in the context of a time-based approach to locomotor activity, in relation to the possible visual methods that might be used in obtaining information about time to contact the target.     

Better than brainstorming? Potential contextual boundary conditions to brainwriting for idea generation in organizations

Organizations and societies all need good, useful ideas to survive and prosper. People often enjoy brainstorming, though it is not as productive as they tend to believe. Groups can potentially generate more and better ideas when ‘brainwriting’; that is, silently sharing written ideas in a time‐ and sequence‐structured group format. This conceptual paper identifies likely boundary conditions to the promising findings from brainwriting laboratory research generalizing to real‐world organizational contexts. Important dimensions of organizational context may be revealed by drawing on the journalistic principle to examine what, who, when, where, and why certain outcomes result from particular organizational practices (Johns, 2006). Multiple potential contextual moderators are suggested in each of these five areas. Subsequent field research will inform the idea‐generation literature as well as those concerned with eliciting high‐quality, useful ideas to address particular organizational and societal challenges.     

How repeatable are Stevens’s power law exponents for individual subjects?

Magnitude estimations of apparent length and apparent area were obtained for the same group of Ss over successive experimental sessions. Session-to-session correlations between individual exponents on a given continuum were positive and reliable for successive 24-h intersession intervals, but were not significant for a 1-year interval. In a second experiment on judgments of apparent area, when each stimulus was judged only once per session, the session-to-session correlation was reliable only when the intersession interval was zero. Six other intervals, ranging from 1 to 77 days, yielded nonsignificant correlations. When the constraints exerted by repeated judging are removed, the location of S’s exponent in a distribution of exponents is stable only for brief intervals. Thus the differences among exponents cannot reflect any persisting attributes of Ss’ sensory or judgmental processes.     

Unification of psychophysical phenomena: The complete form of Fechner’s law

Many of the laws and empirical observations of fundamental psychophysics can be unified with a single equation, which has been called the complete form of Fechner’s law. It can be shown that this law embraces both of the commonly used forms: Stevens’s and Fechner’s laws. It assumes one or the other form with appropriate values of the parameters. However, the complete equation confers an advantage beyond simply containing the classical laws. It offers greater flexibility in the representation of experimental data. It is shown that psychophysical phenomena may be represented by any number of triplets of quantities: subjective magnitude of stimulus, subjective just noticeable difference (jnd), and differential threshold. Each of the preceding quantities are functions of the physical magnitude of the stimulus. The investigator has the license to choose two of these quantities in the form he or she thinks is best; the third quantity is determined by the choice of the first two. Thus, for example, different forms of the law of sensation and different forms of the mathematical function for differential threshold may coexist with equal validity.     

Why doesn’t feedback correct Vierordt’s law?

Vierordt [(1868). Der zeitsinn nach versuchen. Tübingen: Laupp] observed that participants over-reproduce short durations and under-reproduce long durations within a test range of sample durations (Vierordt’s law). Similar phenomena have been reported for sensory and other processing (e.g. [Helson (1964 Helson, H. (1964). Adaptation-level theory. New York, NY: Harper &; Row. [Google Scholar]). Adaptation-level theory. New York: Harper &; Row; Stevens, and Greenbaum (1966). Regression effect in psychophysical judgment. Perception &; Psychophysics, 1, 439–446]. Performance feedback (knowledge of results) does not correct this performance distortion although it does correct other errors. In Experiment 1, I tested the hypothesis that a random presentation order of the standard durations makes feedback on one trial inappropriate for the next trial preventing correction of the Vierordt effect. In Experiment 2, participants performed two consecutive reproductions after each standard duration. Having the opportunity to immediately utilize the feedback from the first reproduction did not eliminate the Vierordt effect, although participants did attempt to correct the error on the first reproduction. In Experiment 3, the Vierordt effect was reduced in a blocked presentation design. Feedback produced more veridical performance. I conclude that the resistance of the Vierordt effect to correction by feedback may result, in part, from feedback on a given trial being misapplied to correcting performance on the next trial. Ironically, the Vierordt effect, which produced the differing directions and magnitudes of performance errors reported by the feedback, may be what prevents feedback from correcting for the Vierordt effect.     

The engineer’s responsibility for quality

This paper offers a definition of quality for products, explains why engineers are morally responsible for quality, and outlines how engineers can fulfill this responsibility. This paper was presented at the Engineering Foundation Conference on “Ethics for Science and Engineering Based International Industries”, Durham, NC, USA, 14–17 September 1997.     

Hick’s law equivalent for reaction time to individual stimuli

Hick’s law, one of the few law-like relationships involving human performance, expresses choice reaction time as a linear function of the mutual information between the stimulus and response events. However, since this law was first proposed in 1952, its validity has been challenged by the fact that it only holds for the overall reaction time (RT) across all the stimuli, and does not hold for the reaction time (RT_i) for each individual stimulus. This paper introduces a new formulation in which RT_i is a linear function of (1) the mutual information between the event that stimulus i occurs and the set of all potential response events and (2) the overall mutual information for all stimuli and responses. Then Hick’s law for RT follows as the weighted mean of each side of the RT_i equation using the stimulus probabilities as the weights. The new RT_i equation incorporates the important speed–accuracy trade-off characteristic. When the performance is error-free, RT_i becomes a linear function of two entropies as measures of stimulus uncertainty or unexpectancy. Reanalysis of empirical data from a variety of sources provide support for the new law-like relationship.     

Visual layout modulates Fitts’s law: The importance of first and last positions

When a target in the last position of a structured visual array is aimed for, movement times (MTs) are shorter than predicted by Fitts’s law (Adam, Mol, Pratt, & Fischer, 2006). That study, however, confounded relative target position with absolute target location. To determine whether target position does, indeed, produce changes in the speed-accuracy trade-off function, the present experiment manipulated relative target position (e.g., first or last) independently of absolute target location (e.g., nearest or farthest). This was accomplished by presenting connected placeholders at three adjacent locations from a set of five possible locations (i.e., the middle location could be the first, middle, or last placeholder position in an array). The results of a speeded manual-pointing task showed that relative position is important for Fitts’s law; when absolute location was held constant, shorter MTs were found for last-position than for middle-position targets. In addition, a similar effect was found for first-position targets. These results suggest that Fitts’s law holds within, but not between, relative target positions in visible structured arrays.     

The latency of response in relation to Bloch’s law at threshold’

Bloch’s law failed to hold for latencies of response in a threshold experiment where frequencies ofresponse did, nevertheless, obey the law. Dark-adapted Ss were instructed to respond as soon as they detected flashes of various luminances and durations. The frequency of response increased with increases in stimulus energy (luminance times duration); it was constant when energy was constant. The latency of response, measured from stimulus onset. varied inversely with energy; it also varied inversely with the luminance of flashes that were constant in energy. The results were consistent with data from earlier threshold and simple reaction time experiments.     

Error is proportional to distance measured by honeybees: Weber’s law in the odometer

Honeybees were trained to fly a specific distance, the same over trials, down a tunnel for a reward. After training, they were tested occasionally with the reward absent. On tests, bees fly to or just past the expected place of reward, then turn around and fly back. After some distance, they turn back again, and may continue turning back and forth a number of times. Past research has shown that distance estimation in this task is based on the retinal flow of visual texture on the walls of the tunnel. Here we measured the errors in distance estimation as a function of training distance. Errors were measured as the standard deviation across trials of the positions of the first two turns (Turn1 and Turn2), and of the Middle (average of Turn1 and Turn2) and Spread (difference between Turn1 and Turn2). All errors were proportional to the training distance, thus obeying Weber’s law. Models of possible mechanisms underlying this phenomenon are discussed. The mean Spread matches the errors in Turn1 and Middle, suggesting that the bee chooses the spread of its search to match the expected odometric error. Received: 28 April 1998 / Accepted after revision: 19 November 1998     

The cognitive advantage for one’s own name is not simply familiarity: An eye-tracking study

Eye-tracking technique and visual search task were employed to examine the cognitive advantage for one’s own name and the possible effect of familiarity on this advantage. The results showed that fewer saccades and an earlier start time of first fixations on the target were associated with trials in which participants were asked to search for their own name, as compared to search for personally familiar or famous names. In addition, the results also demonstrated faster response times and higher accuracy in the former kind of trials. Taken together, these findings provide important evidence that one’s own name has the potential to capture attention and that familiarity cannot account for this advantage.     

The Growing Evidence for Demonic Possession: What Should Psychiatry’s Response be?

Evidence of evil spirits is voluminous and comes from many cultures, both ancient and modern. Cases from China, India, and the United States are examined and evaluated. The actual experience of spirit victims, the universality of spirit oppression, the superhuman phenomena associated with possession, and the comparative success of deliverance and exorcism vs. psychiatry are considered. Potential arguments against the spirit hypothesis center on the antecedent improbability of spirits, multiple personality disorder, and the effectiveness of medication; but these can be countered. Psychiatrists should question their materialist assumption that mental illness is strictly a matter of an aberrant brain, carefully examine the literature of possession, experiment to determine why exorcists and deliverance ministers often succeed where psychiatry fails, and develop a more complete inventory of techniques for healing the complete person.     

Metacognitive control of action: Preparation for aiming reflects knowledge of Fitts’s law

Metacognitive control has been studied in intellectual skills but has not yet been studied in perceptual-motor skills. To probe metacognitive control in a perceptual-motor context, we developed a task in which participants chose the position of a cursor relative to two targets. One of the two targets was randomly erased. Participants tried to move the cursor into the remaining target within a limited amount of time. The target widths were varied, making the difficulty of moving to either target dependent on the chosen cursor position. Predictions were based on the assumption that participants could use an analogue of Fitts’s law to choose optimal positions. The fit between observed and predicted positions was excellent, suggesting that participants used information about movement speed-accuracy trade-offs to guide movement preparation. The findings suggest that metacognition applies to both perceptual-motor skills and intellectual skills, and that these two domains are more similar than traditionally assumed.     

Exploring attention-based explanations for some violations of Hick’s law for aimed movements

Choice reaction time generally increases linearly with the logarithm of the number of potential stimulus-response alternatives, a regularity known as Hick's law. Two apparent violations of this generalization, which have been reported for aimed eye movements (Kveraga, Boucher, & Hughes, Experimental Brain Research, 146, 307-314, 2002), and arm movements (Wright, Marino, Belovsky, & Chubb, Experimental Brain Research, 179, 475-496, 2007), occurred when the indicator stimulus was an abrupt change at the location that was the target of the to-be-made movement. We report two experiments that examined and rejected the hypothesis that these abrupt-onset indicator stimuli triggered a shift in exogenous attention and that this led to unusually small uncertainty effects. Each experiment compared this indicator stimulus with a single alternative: Experiment 1 tested an indicator stimulus at all locations other than the target; Experiment 2 tested a central pointer to the target. Neither alternative led to an uncertainty effect for pointing responses that was of the size typically observed for other responses using the same stimuli.     

Indian Spirituality: How Relevant is Pargament’s Framework?

The psychology of religion and spirituality is a topic of increasing interest in India as well as in the West. An internationally influential framework for defining religion and spirituality has been developed by US psychologist Kenneth Pargament, who conceptualizes spirituality and religion as search processes related to sacred realities. Pargament’s framework has been found to resonate across multiple cultures and has guided and informed empirical research in Jewish, Christian, and Muslim populations. The present paper argues that Pargament’s framework can also coherently resonate with Hinduism and other indigenous Indian religious beliefs and practices. We conclude that future studies of religion and spirituality in Indian contexts may benefit by framing their investigations with reference to Pargament’s approach. Such framing need not be uncritical and would help bring Indian psychology of spirituality/religion in closer contact with psychology of spirituality/religion in other parts of the world, benefiting both India and the worldwide psychology of religion and spirituality.