The organization of multidimensional selection on the basis of color and shape: An event-related brain potential study

In this paper, we examine whether color and shape, tied to a single object in space, (1) are identified and selected in series or in parallel, (2) are identified and selected in a dependent, self-terminating manner or in an independent and exhaustive manner, and (3) are conjoined by a feature integration process before or only after an initial stage of separate attribute analyses has finished. We measured response time and the selection negativity (SN) derived from event-related brain potentials when participants responded to a unique conjunction of color and shape in a go/no-go target detection task. The discriminability of the color and the shape of the conjunction was manipulated in three conditions. When color and shape were easy to discriminate, the SNs to color and shape started at the same time. When one attribute was less discriminable, the SN to that attribute started later, but not the SN to the complementary attribute. This suggests that color and shape are identified and selected in parallel. In all three discriminability conditions, the SNs to color and shape were initially independent but later interacted. This suggests that color and shape are initially selected independently and exhaustively, after which their conjunction is analyzed. The SN to local shape features started later than that to the conjunction of color and global shape features, which suggests that feature integration can start before the analyses of the separate attributes have finished.     

Referenzsemantik in der Partnermodellierung

How can we explain that an assertion on something perceived can be understood in the same manner by somebody who cannot perceive that scene? This problem bases the interest in computational linguistics in how listener modeling could possibly be harmonized with reference semantics. Mental images substituting real perception appear as a way out. The architecture of the listener model has to be adapted to the creation and use of such pictorial data structures. Furthermore, the relation between the latter and a verbal (i. e., propositional) representation must be understood. The resulting architecture of a listener model with reference semantics can be employed to solve communicational problems from three general classes in a better way, as is demonstrated by an example implementation.     

Imperialism,nationalism and missionaries: Lessons from Sudan for the twenty‐first century

Muslim‐Christian relations in modem Sudanese history involve the tensions created by the transition from imperial rule to independence and by the impact of contemporary processes of globalization. The conflicts between Christian missionaries and the newly‐independent government of Sudan in the early 1960s reflected the tensions between old mission‐station style Christian activities and attempts by a military régime to impose measures of ‘national’ unification. Opportunities for creating institutions for constructive interactions were missed or not even conceived. Lessons from the experiences of the early 1960s emphasize the importance of viewing Muslim‐Christian relations in the 1990s in the context of the actual current conditions rather than imposing out‐of‐date images on existing realities.     

The effects of cocaine on behavior maintained by timeout from avoidance.

Rats were trained on concurrent schedules under which responses on one lever postponed shock (avoidance) and responses on the other lever produced brief (2-min) periods of signaled timeout from avoidance. For 6 rats, timeout from avoidance was programmed on a variable-interval 45-s schedule that generally resulted in rates that were lower than those on the avoidance lever. For another 6 rats, timeout was arranged on a variable-ratio 15 schedule that produced higher baseline rates. Cocaine (3 to 40 mg/kg) produced large, dose-dependent increases in behavior maintained by timeout in both groups of rats. Avoidance responding was also generally increased by cocaine, but the increases were of lesser magnitude. Increases in response rates were seen across a broad range of doses on behavior maintained by either interval or ratio schedules, an outcome that was unexpected on the basis of most studies of cocaine on food-maintained behavior. These results were similar to those of previous studies of the effects of amphetamine on behavior maintained by timeout from avoidance and suggest that stimulant drugs affect behavior maintained under a shock-postponement schedule differently than they affect behavior maintained by timeout from avoidance.     

Physicians' values and physician-value neutrality

For years articles have decried the lack of empathy in physicians' relationships with patients. In addition to being empathetic, physicians are called upon to assume the posture of value neutrality, i.e., not imposing one's values when dealing with patients. Empathy is clearly an expression of deeply held values; even the language used to define it is value-laden. Physicians are consistently called upon to exhibit traits which are expressions of their underlying values. However, if proponents of value-neutrality are to be taken literally one must not impose any of one's values on one's patients. But then one wonders how empathy could ever be expressed; further, it is hard to imagine what a truly value neutral physician would be like. It is time we recognize that any relationship between two persons requires the expression of values from both parties. These values help shape that relationship and define its further history. Physicians are not excluded from this process just because they consider themselves professionals. Divulging personal values to patients is both more honest and more in keeping with the concepts of justice, beneficence, non maleficence, and autonomy than to feign value-neutrality. A presentation of some type statement of values is timely and would give patients an idea of where a physician stands on a myriad of issues. Rather than being value-neutral, value non-neutrality seems a more right and reasonable posture for physicians to assume.     

Mindless reading: Eye-movement characteristics are similar in scanning letter strings and reading texts

The purpose of the present study was to compare the oculomotor behavior of readers scanning meaningful and meaningless materials. Four conditions were used—a normal-text-reading control condition, and three experimental conditions in which the amount of linguistic processing was reduced, either by presenting the subjects with repeated letter strings or by asking the subjects to search for a target letter in texts or letter strings. The results show that global eye-movement characteristics (such as saccade size and fixation duration), as well as local characteristics (such as word-skipping rate, landing site, refixation probability, and refixation position), are very similar in the four conditions. The finding that the eyes are capable of generating an autonomous oculomotor scanning strategy in the absence of any linguistic information to process argues in favor of the idea that such predetermined oculomotor strategies might be an important determinant of eye movements in reading.     

Visual slow brain potentials in children with attention deficit disorder

Using a two-stimulus reaction time paradigm, with two separate reward conditions (contingent and noncontingent), we compared slow wave brain potentials (ERPs) in 144 children with attention deficit disorder (ADD) and 30 normal control children. This article reviews the findings during the 900 msec visual warning stimulus. As we had expected, based on ERP work of Forth and Hare (1989) and Raine, Venables and Williams (1990), and on previous work from our own laboratory, the group differences were found in the negative slow wave portions of the ERP complex during the contingent reward condition but not during the noncontingent condition. Aggressive hyperactive subjects with attention deficit disorder (ADDHA) were discriminated from nonaggressive subjects (including control subjects) during the contingent reward condition in the following ways: (1) greater fronto-central negativity (640–900 msec slow wave) and (2) greater right parietal than left parietal negativity (430–750 msec slow wave). All ADD subgroups, when compared to control (CONTR) subjects, showed greater slow wave negativity (700–900 msec) at the midline occipital electrode site during the contingent reward condition. This could be explained in part as an IQ effect on ERPs reflecting the IQ difference between the ADD subgroups and the controls. These slow wave findings seem to relate to attentional problems of these children. They are discussed in terms of a psychobiological model of inhibition/disinhibition and appetitive activation.