Electrophysiological evidence for cognitive control during conflict processing in visual spatial attention

Event-related potentials were measured to investigate the role of visual spatial attention mechanisms in conflict processing. We suggested that a more difficult target selection leads to stronger attentional top-down control, thereby reducing the effects of arising conflicts. This hypothesis was tested by varying the selection difficulty in a location negative priming (NP) paradigm. The difficult task resulted in prolonged responses as compared to the easy task. A behavioral NP effect was only evident in the easy task. Psychophysiologically the easy task was associated with reduced parietal N1, enhanced frontocentral N2 and N2pc components and a prolonged P3 latency for the conflict as compared to the control condition. The N2pc effect was also obvious in the difficult task. Additionally frontocentral N2 amplitudes increased and latencies of N2pc and P3 were delayed compared to the easy task. The differences at frontocentral and parietal electrodes are consistent with previous studies ascribing activity in the prefrontal and parietal cortex as the source of top-down attentional control. Thus, we propose that stronger cognitive control is involved in the difficult task, resulting in a reduced behavioral NP conflict.     

Storage and non-storage components of working memory predicting reasoning: A simultaneous examination of a wide range of ability factors

The current study examined basic cognitive abilities that are related to or included in the concept of working memory (WM): different WM components, three executive functions, simple short-term storage (STM), and sustained attention. Tasks were selected from well-established models and balanced in terms of content. The predictive power of storage and non-storage components of WM was examined. The same analyses were conducted with mental speed as an additional predictor of reasoning. Finally, we investigated whether the identified predictors of reasoning remain relevant when a general factor is considered in the analysis. The analyses revealed that short-term memory accounted for the relationship between complex span measures of WM and reasoning but not for the relationship between coordination and reasoning. These findings remained stable in the context of a mental speed and a general factor. The mental speed factor did not add an incremental contribution to the prediction of reasoning above and beyond short-term memory and coordination. The general factor was mainly built by mental speed tasks and acted as an additional predictor of reasoning besides STM and coordination. Thus, we concluded that reasoning ability can be explained by coordination, STM, and mental speed.     

Age-related impairments of new memories reflect failures of learning,not retention

Learning impairments and the instability of memory are defining characteristics of cognitive aging. However, it is unclear if deficits in the expression of new memories reflect an accelerated decay of the target memory or a consequence of inefficient learning. Here, aged mice (19–21-mo old) exhibited acquisition deficits (relative to 3–5-mo old mice) on three learning tasks, although these deficits were overcome with additional training. When tested after a 30-d retention interval, the performance of aged animals was impaired if initial learning had been incomplete. However, if trained to equivalent levels of competence, aged animals exhibited no retention deficits relative to their young counterparts. These results suggest that age-related “memory” impairments can be overcome through a more effective learning regimen.Aging is associated with broad deficits in the acquisition of new knowledge (Matzel et al. 2008; see, for review, Gallagher and Rapp 1997; Rosenzweig and Barnes 2003), as well as impairments in the retrieval of both old and newly acquired information. While it is clear that old memories (i.e., ones obtained prior to age-related cognitive declines) do in fact become less stable with age (Gallagher 1997), it is less clear whether newly attained memories are inherently less stable in aged animals, or whether age-related memory deficits reflect a secondary consequence of inefficient learning.The majority of published data regarding cognitive aging describes impairments of animals'' learning abilities (Gage and Dunnett 1984; Markowska et al. 1994; Meliska et al. 1997; Nalbantoglu et al. 1997; Vogel et al. 2002; Matzel et al. 2008), although a smaller percentage of these studies also report animals'' performances after long retention intervals. Of those studies that report retention deficits, in most of those studies the initial learning upon which the long-term memory was based was impaired relative to young animals (e.g., Barnes and McNaughton 1985; Kinney et al. 2001a,b; Gould and Feiro 2005). Interestingly, in those few studies in which initial learning was equated across young and old animals, including studies of spatial water maze performance and appetitive instrumental responding, no retention deficits were observed, even after retention intervals as long as 21 d (Soffie and Lejeune 1991; Martinez-Serrano et al. 1996; Port et al. 1996).Although suggestive, the above experiments were not systematically designed to assess the stability of memory in aged animals as a function of the level of initial learning. In the present study, young (3–5 mo) and old (19–21 mo) male Balb/C mice were trained in three learning tasks (a spatial water maze, an egocentric Lashley III maze, and a three-choice odor discrimination). When trained to pre-asymptotic levels, aged animals exhibited both learning and retention deficits (assessed 30 d after initial training). However, when aged animals were trained to levels of competence comparable to their young counterparts, both young and old animals exhibited statistically indistinguishable levels of retention.Sixty Balb/C mice arrived in our laboratory at 2.5 mo (n = 30) or 18.5 mo (n = 30) of age. Each age category was divided into two groups of 15, one of which would receive subasymptotic training on each of the three learning tasks, and one of which would receive extended training on those tasks. Two aged mice became ill during the course of testing and were excluded from all analyses. Young mice ranged from 19.8 to 29.1 g, and aged mice from 26.2 to 37.3 g. Maintenance, food deprivation, and training conditions were as previously described (Matzel et al. 2006, 2003). Behavioral testing of young and aged mice was concluded at ∼5 and 21 mo of age, respectively.All animals were tested in three independent learning tasks. Briefly, the spatial water maze encourages mice to integrate spatial information to efficiently escape from a pool of water. In odor discrimination, animals must use a target odor (from a group of three odors) to guide their search for food. In the Lashley III maze, animals learn an egocentric sequence of turns to obtain a food reinforcer. Training on each task required 2–10 d (depending on the task and the level of training), and animals received four days of rest between tasks. A retention test was administered 30 d after the last training trial of each task.A Lashley III maze was constructed from black Plexiglas. A 3-cm-diameter white disk was located in the center of the goal box, and a 45 mg Bio-Serv food pellet (dustless rodent grain) was placed at the center of the disk and served as the reinforcer. Food-deprived animals received a day of acclimation to the maze, followed by either one or two days of training (four trials/day). On the day prior to the acclimation, animals received three Bio-Serv pellets in their home cage (thus mitigating any neophobia to the food on subsequent exposures). On the acclimation day, each mouse was confined in each of the first three alleys of the maze for 4 min, and in the final alley (containing the goal box) for 6 min. On this acclimation day, three Bio-Serv pellets were placed in the goal box. On the subsequent training day(s), each animal was placed in the start box and allowed to freely navigate the maze, during which time the number of errors to reach the goal box were recorded. (An error was constituted by a turn in the wrong direction or a retracing of a previously completed path.) Upon consuming the food pellet, the animal was returned to its home cage for a 25-min intertrial interval (ITI). All animals completed four trials during the first training day. Half of those animals then received an additional four training trials on the following day. Twenty-nine days after the last training trial, all animals received three Bio-Serv pellets in their home cages, and on the subsequent day were again tested in the maze.For the water maze, a round pool (140 cm diameter, 56 cm deep) was filled to within 20 cm of the top with water that was clouded with a water soluble black paint. A hidden 14-cm-diameter black platform was located in a fixed position 1 cm below the surface of the water. The pool was enclosed by a ceiling high black curtain on which five different light patterns (which served as spatial cues) were fixed at various positions. These light cues provided the only illumination of the maze, which was 60 Lux at the water''s surface.On the day prior to training, each animal was confined for 360 sec to the platform by a clear Plexiglas cylinder that fits around the platform. For either one or two training days (six trials Day 1, five trials Day 2), the animals were started from one of three positions, such that no consecutive trials started from the same position. After locating the platform or swimming for 90 sec, the animals were left or placed on the platform for 10 sec, after which they were placed in a holding box (for 12 min) before the start of the next trial. After the sixth or 11th training trial, animals were returned to their home cages for 3 h, and were then administered a 30-sec “probe” test in which the escape platform was removed from the maze and the time spent searching in the target quadrant was recorded. One hour later each animal received an additional training trial (intended to re-establish the search strategy employed by the animal prior to the probe test). Animals were then returned to their home cages, where a 30-d retention interval began.In odor discrimination, mice navigate through a field using unique odors to guide them. The animals learn to choose the food cup that contains the target smell when given three choices. The food cup locations are rearranged on each trial, but the accessible food is always marked by the same target odor (in this case mint). The chamber consisted of a black Plexiglas 60-cm-square field with 30-cm-high walls, which was located in a dimly lit room with high ventilation. A food cup was located in three corners. The target cup had accessible food (30 mg of chocolate puffed rice), while the remaining cups contained food that could not be accessed. A cotton tipped swab (2-cm long) was loaded with 25 μL of lemon-, mint- (the target odor), or almond-flavored extract and extended vertically from the back corner of each cup.Each animal had one day of acclimation and one day of training (consisting of four training trials). (In this task, both young and old animals reached asymptotic levels of performance [near errorless] within four training trials.) On Day 1 (adaptation), each mouse was placed in the box for 20 min with no food cups present. On the subsequent training day, a food cup was placed in three corners of the field, but only the cup associated with the mint odor contained accessible food. Each animal received four trials in which they were placed in the corner of the training chamber that did not contain a food cup. A trial continued until the animal obtained the food from the target location, at which time the animal was returned to its home cage to begin a 20 min ITI. At the end of each trial the food cups were rearranged, but mint always remained as the target odor. For each trial, the number of errors (contact with or sniffing within 2 cm of an incorrect food cup) was recorded. After the fourth training trial, the animal was returned to its home cage for a 30-d retention interval. On the 29th retention day, all animals received three pieces of chocolate flavored rice in their home cages, and on the subsequent day were again tested as in original training.     

The Global Scope of Justice

In this paper, I examine the question of the scope of justice, in a not unusual distributive, egalitarian, and universalistic framework. Part I outlines some central features of the egalitarian theory of justice I am proposing. According to such a conception, justice is – at least prima facie – immediately universal, and therefore global. It does not morally recognize any judicial boundaries or limits. Part II examines whether, even from a universalistic perspective, there are moral or pragmatic grounds for rejecting or limiting the global scope of justice. In particular, I scrutinize five universalistic objections: (1) the principle of "moral division of labor"; (2) the connection between cooperation and distributive justice; (3) the primacy of democracy; (4) the dangers of a world state; and (5) political-pragmatic reasons. I intend to show that these objections cannot undermine the strong normative claims of global justice. At the most, political-pragmatic reasons speak in favor of initially striving for somewhat less, in order to receive more general backing.     

Standardization and the competition on the market for ERP-systems

Although frameworks appear to be a promising means to provide the industry with business management software, one cannot observe that framework vendors begin to threat the market position of vendors of established standard software. We build a microeconomic model to analyze the competition of software development with or without frameworks in which we concentrate on the network effect and the effect of compatibility decisions. We can show how the introduction of a standard will help to establish framework technology on the software market and finally increase social welfare. Therefore we recommend the standardization organizations to support framework technology by establishing standards.     

The place of the unconscious in critiques of systematic prejudice: Lessons from MacKinnon and Critical Race Theory

In this paper, I argue that so called “systematic critiques” of the liberal conception of law in Catherine MacKinnon and Critical Race Theory which have traditionally been seen to reject liberalism should really be understood as subjecting the liberal conception of law as impartial and just to an immanent critique. Critical Race Theory and MacKinnon both seek to unmask the seemingly neutral subject which authorizes law as in reality a hegemonic and oppressive subject. They also employ the tools of liberalism, demanding justice and equal protection under the law. I argue that the apparent contradiction of their demands can be understood by seeing the subject itself as combining these contradictions at the level of the relation between the unconscious and consciousness. The ego strives for rational self-organization while the unconscious contains sedimented socially transmitted prejudice. There is thus room within both for the struggle for freedom and justice espoused by liberalism at the conscious level as well as for the unconscious perpetuation of prejudice and domination. I conclude that MacKinnon’s work and that of CRT show that liberalism must not be abandoned as post-structuralism does, but that liberals is in fact aided by its critics.