An object-oriented simulation of a brain system underlying human aggression

Neural structures involved in aggression were incorporated into a model on the basis of neuro-anatomical data. A software program written in Smalltalk, the Brain Structure Simulator (Seguin, 1994) was used to simulate the effects of activity levels of different brain structures. Relationships among brain structures were then tested by changing activity levels of key structures. Results were consistent with research reports on the brain basis of aggression (Albert, Walsh, & Jonik, 1993; Pontius, 1984).     

A program for parsing mouse movements into component submovements

Most current movement control theories include the idea that movement toward a target can be broken into several submovements. The complexity of analyzing a movement into its constituent submovement structure and the additional complexity imposed by the problem of noise in the data and hand tremor seem to be daunting to researchers. This paper discusses a program that can ameliorate both of these problems and parse movements into their constituent submovements. It also contains a graphing feature that is useful as a visual tool for analyzing submovement structure. The programs are easily modifiable, so that researchers can specify their own parsing rules on the basis of different assumptions about movement control and use the parser for data from different experimental tasks.     

The Progression and regression of slave morality in Nietzsche's Genealogy: The moralization of bad conscience and indebtedness

With the advent of slave morality and the belief system it entails, human beings alone begin to advance to a level beyond that of simple, brute, animal nature. While Christianity and its belief system generate a progression, however, allowing human beings to become interesting for the first time, Nietzsche also maintains in the Genealogy that slave morality is a regression, somehow lowering or bringing them down from a possible higher level. In this paper I will argue that this is not a mere inconsistency in Nietzsche's writing, but is instead an important clue to a correct interpretation of the Genealogy.     

Asymmetries and errors in perception of depth from disparity suggest a multicomponent model of disparity processing

In three experiments, asymmetries between the processing of crossed and uncrossed disparities were investigated. The target was a luminance-defined circle concentric to a fixation mark, viewed stereoscopically on a computer monitor for 105 msec. Fifteen disparities were presented according to the method of constant stimuli. Observers indicated the apparent direction of target depth relative to fixation. All experiments measured both the accuracy and latency of this response. Experiment 1 showed fewer errors and shorter reaction times for identifying crossed disparities. Experiments 2 and 3 replicated Experiment 1 and also showed that observers may often perceive a target in the direction opposite that prescribed by the disparity information. We propose that the asymmetries and reversals result from differences in computation of sign, not of magnitude. This notion is consistent with a scheme of continuous disparity tuning and accounts for such asymmetries and errors without positing disparity pooling mechanisms.     

The Individuation of Actions

I argue against a view of the individuation of actions endorsed most notably by Hornsby and Davidson. This is the view that in, for example, Anscombe's case of the pumping man, we have a single action which can be described, variously, as a pumping, a poisoning and so on. I argue that, even in the area of the standard arguments against this view, such as that based on the logic of 'by' and the argument from temporal dimensions, the case against the Davidson-Hornsby view has not been made as strong as it ought to have been. I show how those standard arguments can be strengthened; and I argue that the principal considerations adduced in support of the view do not in fact lend it the support that they have been widely thought to lend it. I conclude that the view should be rejected.     

How Can Pictures be Propositions?

Wittgenstein's Picture Theory of language holds that one fact can represent another, and that propositions are pictures of states of affairs. What makes a fact into a picture of a given s tate of affairs are the correlations between picture elements and objects and the correlations between relations among picture elements and relations among objects. But a problem sometimes raised is that propositions can't be pictures, as pictures—unlike propositions—do not say anything. An interpretation (e.g. Anscombe's) holds that the above-mentioned correlations do make the picture into a proposition. But this neither handles the objection, nor is it Wittgenstein's view. Further, Wittgenstein's own account faces serious difficulties in addressing these issues, and the Anscombe-type interpretation obscures this fact.     

Semantic satiation in healthy young and older adults

In four experiments, semantic satiation was investigated in young and old adults. In the first two experiments, subjects were repeatedly presented a word (e.g.,dog) and then were presented a pair of words (e.g.,dog-cat ordog-chair) for a relatedness decision. The results of both experiments indicated that for the young adults, the relatedness effect (the difference between response latency on related and unrelated trials) decreased as a function of the number of times the satiated word was repeated, whereas for the older adults, there was no evidence of a decrease in the relatedness effect across repetitions of the satiated word. In the third experiment, we investigated whether phonological codes are also susceptible to satiation. This experiment was similar to the first two experiments with the exception that subjects made rhyme decisions (same-claim vs.same-dime) instead of semantic relatedness decisions. The results of this experiment did not yield any evidence of satiation for either the young adults or the older adults. The final experiment eliminated a simple decrease in attentional alertness or fatigue account of the semantic satiation effects found in the first two experiments. In this experiment, the repeated word was always unrelated to the pair of words presented for the relatedness decision. The results of this experiment did not yield any evidence of semantic satiation for either the young or the older adults. The discussion focuses on the mechanisms underlying semantic satiation and the implications of age-related changes in these mechanisms.     

The Use of Contextual Information by Right Brain-Damaged Individuals in the Resolution of Ambiguous Pronouns

Two experiments were conducted with the primary purpose of investigating the ability of right brain-damaged (RBD) individuals to use contextual information—at the level of the single sentence, in terms of the integration of information between clauses, and at the level of a minimal discourse (i.e., two sentences)—in the resolution of ambiguous pronouns. The investigation was extended to a group of left brain-damaged (LBD) and non-brain-damaged (NBD) individuals. Contrary to the prevailing view that RBD patients have difficulty in the use of contextual information to process language, both experiments were consistent in demonstrating that the RBD group was influenced by contextual information in a manner similar to that demonstrated by both the LBD and NBD groups.