Andrew T. Marshall

Bio: Andrew T. Marshall is an academic researcher from University of Southern California. The author has contributed to research in topics: Medicine & Psychology. The author has an hindex of 14, co-authored 42 publications receiving 565 citations. Previous affiliations of Andrew T. Marshall include University of California, Irvine & Children's Hospital Los Angeles.

Association of lead-exposure risk and family income with childhood brain outcomes

Abstract: Socioeconomic factors influence brain development and structure, but most studies have overlooked neurotoxic insults that impair development, such as lead exposure. Childhood lead exposure affects cognitive development at the lowest measurable concentrations, but little is known about its impact on brain development during childhood. We examined cross-sectional associations among brain structure, cognition, geocoded measures of the risk of lead exposure and sociodemographic characteristics in 9,712 9- and 10-year-old children. Here we show stronger negative associations of living in high-lead-risk census tracts in children from lower- versus higher-income families. With increasing risk of exposure, children from lower-income families exhibited lower cognitive test scores, smaller cortical volume and smaller cortical surface area. Reducing environmental insults associated with lead-exposure risk might confer greater benefit to children experiencing more environmental adversity, and further understanding of the factors associated with high lead-exposure risk will be critical for improving such outcomes in children. Cross-sectional analysis of data from the Adolescent Brain Cognitive Development Study shows that children from families with low income are at increased risk of cognitive impairment associated with high lead-exposure risk when compared with children from families with high income.

Mechanisms of impulsive choice: i. individual differences in interval timing and reward processing

Abstract: Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment 1, rats were trained to discriminate a short (2 s) vs. a long (8 s) signal followed by testing with intermediate durations. Then, the reward on short or long trials was increased from 1 to 4 pellets in separate groups. Experiment 2 measured the effect of different reward magnitudes associated with the short vs. long signals throughout training. Finally, Experiment 3 controlled for satiety effects during the reward magnitude manipulation phase. A general flattening of the psychophysical function was evident in all three experiments, suggesting that unequal reward magnitudes may disrupt attention to duration.

Evolution of user interaction: the case of agent adele

Abstract: Animated pedagogical agents offer promise as a means of making computer-aided learning more engaging and effective. To achieve this, an agent must be able to interact with the learner in a manner that appears believable, and that furthers the pedagogical goals of the learning environment. In this paper we describe how the user interaction model of one pedagogical agent evolved through an iterative process of design and user testing. The pedagogical agent Adele assists students as they assess and diagnose medical and dental patients in clinical settings. We describe the results of, and our responses to, three studies of Adele, involving over two hundred and fifty medical and dental students over five years, that have led to an improved tutoring strategy, and discuss the interaction possibilities of two different reasoning engines. With the benefit of hindsight, the paper articulates the principles that govern effective user-agent interaction in educational contexts, and describes how the agents interaction design in its current form embodies those principles

Review of Research.

Abstract: According to WHO, the permissible limit of arsenic till 1993 was 0.05 mg. /L of drinking water. In 1993, WHO modified the maximum level and brought it down to 0.01 mg./L. According to the report of School of Environment Studies of Jadavpur University (1992-1993), West Bengal has 6 districts, affected by arsenic contamination of ground water. The present paper attempts to find out the vulnerability and impact of arsenic on human being. A detailed survey was conducted at Dahapara village of Murshidabad district to assess the present condition of the area giving emphasis on the identification of sources of arsenic pollution.

Age and Sex

Abstract: Throughout life, women’s sexuality is more dependent on the existence and nature of a relationship with a partner than is that of men. The evidence that this is the case in adolescence, early adulthood, and middle and old age will be discussed in relation to these life stages. It may explain or result from the greater importance psychological (as opposed to biological) factors have on women’s sexuality as compared to men’s. Despite the overwhelming importance given in the United States to environmental as compared to biological variables in determining human behavior (McConaghy, 1987b), some of its theorists have considered the differences between the behavior of men and women to be genetically determined by the form of sexual activity selected in the evolution of human beings to enable the survival of their species (Knoth, Boyd, & Singer, 1988).

The anticipation and outcome phases of reward and loss processing: a neuroimaging meta-analysis of the monetary incentive delay task

Abstract: The processing of rewards and losses are crucial to everyday functioning. Considerable interest has been attached to investigating the anticipation and outcome phases of reward and loss processing, but results to date have been inconsistent. It is unclear if anticipation and outcome of a reward or loss recruit similar or distinct brain regions. In particular, while the striatum has widely been found to be active when anticipating a reward, whether it activates in response to the anticipation of losses as well remains ambiguous. Furthermore, concerning the orbitofrontal/ventromedial prefrontal regions, activation is often observed during reward receipt. However, it is unclear if this area is active during reward anticipation as well. We ran an Activation Likelihood Estimation meta-analysis of 50 fMRI studies, which used the Monetary Incentive Delay Task (MIDT), to identify which brain regions are implicated in the anticipation of rewards, anticipation of losses, and the receipt of reward. Anticipating rewards and losses recruits overlapping areas including the striatum, insula, amygdala and thalamus, suggesting that a generalised neural system initiates motivational processes independent of valence. The orbitofrontal/ventromedial prefrontal regions were recruited only during the reward outcome, likely representing the value of the reward received. Our findings help to clarify the neural substrates of the different phases of reward and loss processing, and advance neurobiological models of these processes.

The politeness effect: Pedagogical agents and learning outcomes

Abstract: Pedagogical agent research seeks to exploit Reeves and Nass's media equation theory, which holds that users respond to interactive media as if they were social actors. Investigations have tended to focus on the media used to realize the pedagogical agent, e.g., the use of animated talking heads and voices, and the results have been mixed. This paper focuses instead on the manner in which a pedagogical agent communicates with learners, i.e., on the extent to which it exhibits social intelligence. A model of socially intelligent tutorial dialog was developed based on politeness theory, and implemented in an agent interface within an online learning system called virtual factory teaching system. A series of Wizard-of-Oz studies was conducted in which subjects either received polite tutorial feedback that promotes learner face and mitigates face threat, or received direct feedback that disregards learner face. The polite version yielded better learning outcomes, and the effect was amplified in learners who expressed a preference for indirect feedback, who had less computer experience, and who lacked engineering backgrounds. These results confirm the hypothesis that learners tend to respond to pedagogical agents as social actors, and suggest that research should focus less on the media in which agents are realized, and place more emphasis on the agent's social intelligence.