Perceived numerosity of spatiotemporal events

Numerosity discrimination was examined when items were varied in space-time position rather than in space only. Observers were instructed to indicate which of two adjacent streamsof visual events contained more items. The precision of numerosity discrimination of dynamic events was not remarkably different from that of static patterns. Two basic numerosity biases previously found for static dot patterns—inhibitory overestimation and satellite underestimation—were demonstrated for items distributed randomly over a spatiotemporal interval. It was also demonstrated that two streams, equated in the number and luminous energy of items, are not judged equal in their visible number if items in one of these two streams have longer duration than items in the second stream. These findings can be accounted for by the occupancy model of perceived numerosity (Allik & Tuulmets, 1991a) if it is supposed that the impact that each element has on its neighborhood is spread along both spatial and temporal coordinates. Perceived numerosity decreases with both spatial and temporal proximity between the-visual-items. Space and time have interchangeable effects on perceived numerosity: the amount of numerosity bias caused by the spatial proximity of items can also be produced by the properly chosen temporal proximity of items     

Additivity of loudness across critical bands: A critical test

The use of magnitude estimation as well as axiomatic measurement theory has led to the suggestion that loudness adds across critical bands. In the present paper, we challenge this postulate by applying a more sensitive methodology, based on Falmagne’s (1976) random conjoint measurement procedure. A necessary condition for additivity of loudness was investigated in tone complexes consisting of 2-kHz and 5-kHz (resp. 3-kHz) components; the results showed systematic deviations from additivity. We argue that these deviations are due to asymmetric masking of the higher component by the lower one, and we propose a tentative quantitative model to account for the data. Such a model is in line with results from tone-on-tone masking, which show masking to be effective over a range of several critical bands.     

On reduced matrices

It is shown that the class of reduced matrices of a logic is a 1 ^st order -class provided the variety associated with has the finite replacement property in the sense of [7]. This applies in particular to all 2-valued logics. For 3-valued logics the class of reduced matrices need not be 1 ^st order.     

Neuroleptic malignant syndrome--3 case reports

An account is given of three patients who exhibited a malignant neuroleptic syndrome after the administration of neuroplegics. Like other authors, we identified typical elicitation factors and clinical characteristics. In one case a catatonic dilemma with lethal issue was observed. In the final case dealt with in this paper, the renewed application of neuroplegics following the termination of the malignant neuroleptic syndrome was tolerated without complications, whereas in the case of an epileptic patient with damage to the brain, the malignant neuroleptic syndrome returned upon dosage increase.     

Questions at the general hospital. Ulcerative colitis and Crohn disease in the light of a discussion on the body and soul

The author is an internist in a non-university hospital. He discusses the possibilities and limits of dealing with patients suffering from ulcerative colitis and Crohn's disease. He demonstrates the clinical importance of a psychoanalytic perspective with three case illustrations.     

Toward a Process Analysis of Emotions: The Case of Surprise

Based on an earlier model of the processes elicited by surprising events, the present studies provide evidence for one of these processes, the evaluation of the surprising event's relevance for ongoing activities (action-relevance check). The central prediction tested was that, if unexpected events elicit among other processes an action-relevance check, then response delay on a concurrent task will be more pronounced in a condition where this process is more elaborate and hence takes more time. In accord with this prediction, Experiment 1 found that an unexpected appearance change of the imperative stimulus in a choice reaction time (RT) task caused greater response delay than an equivalent appearance change of a distractor stimulus. Experiment 2 replicated this finding and tested several additional predictions that concerned the effects on response delay of a second appearance change of either the imperative or the distractor stimuli. These predictions, which were also mostly confirmed, were derived by combining the logic underlying the first study with the assumption that once made, appraisals of unexpected events are stored as part of the situational schema and are reused when the same or similar events reoccur leading to an abbreviation of appraisal processes. Experiment 3 once more replicated the basic finding of the previous studies and ruled out a possible alternative explanation. It is suggested that the proposed RT method of process verification may be of broader interest as a tool to study appraisal processes in emotion.     

Heading and path information from retinal flow in naturalistic environments

In four experiments, we explored the heading and path information available to observers as we simulated their locomotion through a cluttered environment while they fixated an object off to the side. Previously, we presented a theory about the information available and used in such situations. For such a theory to be valid, one must be sure of eye position, but we had been unable to monitor gaze systematically; in Experiment 1, we monitored eye position and found performance best when observers fixated the designated object at the center of the display. In Experiment 2, when we masked portions of the display, we found that performance generally matched the amount of display visible when scaled to retinal sensitivity. In Experiments 3 and 4, we then explored the metric of information about heading (nominal vs. absolute) available and found good nominal information but increasingly poor and biased absolute information as observers looked farther from the aimpoint. Part of the cause for this appears to be that some observers perceive that they have traversed a curved path even when taking a linear one. In all cases, we compared our results with those in the literature.     

The effect of spatial frequency on global precedence and hemispheric differences

There are many conditions in which identification proceeds faster for the global form of a hierarchical pattern than for its local parts. Since the global form usually contains more lower spatial frequencies than do the local forms, it has frequently been suggested that the higher transmission rate of low spatial frequencies is responsible for the global advantage. There are also functional hemispheric differences. While the right hemisphere is better at processing global information, the left hemisphere has an advantage with respect to local information. In accordance with the spatial-frequency hypothesis, it has been speculated that this difference is due to a differential capacity of the hemispheres for processing low and high spatial frequencies. To test whether low spatial frequencies were responsible for the global advantage and/or for the observed hemispheric differences, two experiments were carried out with unfiltered and highpass-filtered compound-letter stimuli presented at the left, right, or center visual field. The first experiment, in which the target level was randomized in each trial block, revealed that low spatial frequencies were not necessary for either global advantage or for hemispheric differences. Highpass filtering merely increased the response times. In the second experiment, the target level was held constant in each block. This generally increased the speed of responding and produced interactions between filtering and global-local processing. It was concluded that both sensory and attentional or control mechanisms were responsible for global precedence and that the hemispheres differed with respect to the latter.     

Fractal Images of Formal Systems

Formal systems are standardly envisaged in terms of a grammar specifying well-formed formulae together with a set of axioms and rules. Derivations are ordered lists of formulae each of which is either an axiom or is generated from earlier items on the list by means of the rules of the system; the theorems of a formal system are simply those formulae for which there are derivations. Here we outline a set of alternative and explicitly visual ways of envisaging and analyzing at least simple formal systems using fractal patterns of infinite depth. Progressively deeper dimensions of such a fractal can be used to map increasingly complex wffs or increasingly complex value spaces, with tautologies, contradictions, and various forms of contingency coded in terms of color. This and related approaches, it turns out, offer not only visually immediate and geometrically intriguing representations of formal systems as a whole but also promising formal links (1) between standard systems and classical patterns in fractal geometry, (2) between quite different kinds of value spaces in classical and infinite-valued logics, and (3) between cellular automata and logic. It is hoped that pattern analysis of this kind may open possibilities for a geometrical approach to further questions within logic and metalogic.\looseness=-1