Concurrent Discrimination Research Articles

The Economic History & Urban Geography of Race Relations in Detroit: Movement of Capital, White Resistance and Immobility of Black Labor

Detroit's intertwined history of deindustrialization and racial segregation is often explored separately. In The Origins of the Urban Crises (1996), Thomas Sugrue examines post-WWII job losses and housing discrimination without elucidating why and how the city came to experience the abrupt flight of capital in that period. Conversely, Murray and Schwartz's Wrecked (2019) details the catalysts for Detroit's deindustrialization but neglects its impact on the African-American community. This paper aims to bridge these perspectives by utilizing various secondary sources and archival evidence to analyze how concurrent discrimination and economic decline have maintained the persistent segregation between Detroit and its suburbs.

Higher Number of Children Is Associated With Increased Risk of Generalization Deficits in Older African American Women.

The objectives of this project were to: (1) examine the relationship between the number of biological children and hippocampal-dependent cognitive performance among older African American women and (2) determine the influence of socioeconomic status (i.e., age, education, marital status, median household income), if any, on this relationship. A total of 146 cognitively unimpaired African American women aged 60 and older were recruited from the greater Newark area and reported their number of biological children, marital status, educational level, and age. We retrieved median household income from census tract data based on the participants' addresses. Participants' cognitive performance was assessed using the Rey Auditory Verbal Learning Test (RAVLT) long delay recall and a Rutgers generalization task (Concurrent Discrimination and Transfer Task). As the number of biological children a woman has had increases, the number of generalization errors also increased, indicating poorer hippocampal-dependent cognitive performance when controlling for age, education, marital status, and median household income. There was no significant relationship between the number of children and performance on a standardized neuropsychological measure of episodic memory (RAVLT), although education was a significant covariate. Generalization tasks may better capture early changes in cognitive performance in older African American women who have had children than standardized neuropsychological assessments. This finding may be explained by the fluctuations in estrogen associated with having children. Future studies should explore how these findings can be applied to protecting cognitive function and preventing Alzheimer's disease in older African American women who have had children.

Preliminary Assessment of Siamang (Symphalangus syndactylus) Cognition Using Digital Cognition Testing Software and Touchscreen Technology

Studies of nonhuman primate cognition have traditionally employed subjects from the monkey (Cercopithecoidea) and ape (Hominidae) lineages, with relatively much less examination of the phylogenetically intermediate gibbons (Hylobatidae). To begin to rectify this gap in our understanding of primate cognition, we used a short-term training and testing method to preliminarily evaluate siamang gibbon (Symphalangus syndactylus) performance on a battery of standardized cognitive tasks, using Monkey CANTAB cognition testing software (Lafayette-Campden Neuroscience) and a computer touchscreen apparatus. Five different operant tasks examining distinct perceptual and cognitive functions were used to train and test each subject over a period of five weeks. Over 1900 cognitive testing trials were completed with three subjects. Despite limited training and testing opportunity, all siamangs achieved proficiency scores well above chance (> 65%) in both Concurrent Discrimination and Spatial Working Memory tasks. Over the limited training opportunities available, our subjects did not achieve proficiency in Delayed Match-to-Sample, Paired Associates Learning, or Conditional Visual Discrimination tasks; however, subjects did exhibit (to varying degrees) improved performance in these tasks, suggesting that additional training may lead to higher proficiency and that siamangs demonstrate effective, task-based learning capabilities. We present one of the first successful tests of a hylobatid ape using touchscreen cognitive testing methods and demonstrate that hylobatids can be evaluated using the same methods now commonly employed in tests of other nonhuman primates. Further, our testing regime proved to be behaviorally rewarding for our subjects, suggesting that hylobatids may benefit from advanced forms of interactive cognitive enrichment.

Perceived ethnic discrimination and cognitive function: A 12-year longitudinal study of Mexican-origin adults

ObjectivesHispanic/Latinx adults are at increased risk for cognitive impairment, and it is critically important to identify modifiable risk factors for cognitive impairment in this population. We addressed two key questions: (1) How does perceived discrimination change across middle adulthood? And, (2) how are discrimination and the trajectory of discrimination associated with cognitive function? MethodsWe used data from 1,110 Mexican-origin adults between 26 and 62 years old (63% female; 85% born in Mexico). Participants completed a perceived ethnic discrimination scale five times across 12 years and completed cognitive assessments in the last wave, which were composited into a measure of overall cognitive function. We used latent growth curve models to estimate the longitudinal trajectory of perceived ethnic discrimination and growth mixture models to identify sub-groups of change trajectories. We evaluated whether patterns of perceived discrimination trajectories, baseline, intermediary, and concurrent discrimination predicted cognitive function at the last wave. ResultsPerceived ethnic discrimination decreased over time on average. Significant individual differences in within-person change revealed two change trajectory classes: Stable Low and High Declining. The Stable Low class had better cognitive performance compared to the High Declining class, but this effect was not robust to educational attainment. Perceived discrimination at the last wave was associated with worse cognitive function, and this effect remained after accounting for covariates. ConclusionsThis study is among the first to evaluate changes in perceived ethnic discrimination in a sample of Mexican-origin adults and their associations with cognitive function. The results highlight the need for more research to better understand the role of discrimination and other social stressors on cognitive health outcomes.

APOE‐ε4 status moderates the relationship between body mass index and hippocampal structure in older African Americans

AbstractBackgroundGrowing evidence suggests that traditional body mass index (BMI) cutoff values may overestimate adiposity and its health consequences in African Americans. Further, while obesity disproportionately affects African Americans, obesity is inconsistently associated with Alzheimer’s disease (AD) in older adulthood. Examining the influence of BMI and its interaction with the strongest genetic risk factor of AD, the APOE‐ε4 allele, on hippocampal‐dependent cognitive performance and medial temporal lobe (MTL) structure may provide insights into the complex relationship between obesity and AD in older African Americans.MethodAnalyses included 70 cognitively normal older African Americans (mean age=69.50 years, SD=7.18; mean education=14.12 years, SD 2; 38.60% APOE‐4 allele carriers) who completed cognitive testing, saliva sampling for APOE genotyping, and structural neuroimaging to extract MTL cortical region/hippocampal subfield volumes and surface areas. Cognitive tests included the following measures of generalization and episodic memory: Concurrent Discrimination and Transfer Task, Acquired Equivalence Task, and Rey Auditory Verbal Learning Test. ANCOVAs were used to compare BMI groups (normal: 18‐24.9 kg/m2; overweight: 25‐29.9 kg/m2; class 1 obesity: 30‐34.9 kg/m22) and to test for BMIxAPOE interactions on cognitive and neuroimaging outcomes, while controlling for age, sex, education, literacy, and depressive symptomology.ResultThere was a statistically significant difference between BMI groups on Concurrent Discrimination and Transfer Task performance, p=.01, partial η 2=.18. The normal and class 2 obesity group committed significantly greater errors than either the overweight or class 1 obesity group, ps < .05. Significant BMIxAPOE interactions were identified for the following hippocampal subfield volumes and surface areas: left DG/CA3 and left CA1, ps < .05. For APOE‐ε4 non‐carriers, the normal BMI group had significantly smaller left DG/CA3 and CA1 subfields than the other groups. Among APOE‐ε4 carriers, the class 2 obesity group had smaller left DG/CA3 and CA1 subfields than the other groups.ConclusionBeing overweight may confer cognitive protection in older African Americans. However, obesity appears to be selectively detrimental to hippocampal subfield structure among APOE‐ε4 carriers while normal BMI may be deleterious to hippocampal subfield structure among APOE‐ε4 non‐carriers.

Does mental health-related discrimination predict health service use 2years later? Findings from an Australian national survey.

Stigma and discrimination are central concerns for people with mental health problems. The aim of the study was to carry out a follow-up survey of a national survey of experiences of avoidance, discrimination and positive treatment in people with mental health problems to explore how those experiences relate to health service use. In 2017, telephone interviews were carried out with 655 Australians aged 18+, who had participated in a 2014 survey and reported a mental health problem or scored highly on a symptom screening questionnaire. Questions covered mental health, disclosure, health service utilisation, and experiences of avoidance, discrimination and positive treatment in a variety of different settings. Regression analyses were used to assess the extent to which count of settings of experiences of avoidance, discrimination or positive treatment at baseline (2014) or follow-up (2017) predicted health service use at follow-up. An increase in past experiences of discrimination was associated with a greater number of visits to hospital or specialist doctors and an increase in positive treatment was associated with a greater number of visits to a mental health professional. Increases in both positive and negative experiences were associated with greater healthcare costs, but the costs were greatest for discrimination at follow-up (concurrent discrimination), primarily due to the cost of nights in hospital. While both discrimination and positive treatment are associated with greater healthcare costs, concurrent experiences were shown to be more important correlates of health service use than past experiences. Moreover, those in supportive environments may be more willing to engage in earlier evidence-based treatment for mental health problems.

Psychometric properties of the problem solving inventory in a Singapore young male adult sample

The Problem Solving Inventory (PSI) is a widely used instrument that measures problem-solving appraisal, which has been associated with suicidal ideation. However, the PSI has yielded different factorial structures in Western and Asian studies. The aim of the current study was to evaluate the psychometric properties of the PSI with a Southeast-Asian sample made of 342 young adult males living in Singapore. The participants completed the PSI, Depression Anxiety Stress Scale (D-Scale), Interpersonal Needs Questionnaire, Hope Scale, and Suicidal Ideation Scale. Confirmatory factor analyses showed that the data fitted a three-factor model (problem-solving efficacy [PSE], rational coping [RC], and dysfunctional coping [DC] factors), supporting previous findings in Asia. Appropriate internal reliability for the total (.83) and the three subscales, .85 (PSE), .72 (RC), and .73 (DC), was found. Convergent validity was shown by significant correlations between problem solving appraisal and depression, interpersonal needs, and hope. Predictive validity was attested with positive correlations between problem solving appraisal and suicidal ideation. Concurrent discrimination was also demonstrated by differences in problem-solving appraisals between groups with low and high depression, interpersonal needs, hope, and suicidal ideation. The findings showed that the PSI with a three factors solution was a valid and reliable scale for use with young male Singaporeans.

Manipulating memory efficacy affects the behavioral and neural profiles of deterministic learning and decision-making

When making a decision, we have to identify, collect, and evaluate relevant bits of information to ensure an optimal outcome. How we approach a given choice can be influenced by prior experience. Contextual factors and structural elements of these past decisions can cause a shift in how information is encoded and can in turn influence later decision-making. In this two-experiment study, we sought to manipulate declarative memory efficacy and decision-making in a concurrent discrimination learning task by altering the amount of information to be learned. Subjects learned correct responses to pairs of items across several repetitions of a 50- or 100-pair set and were tested for memory retention. In one experiment, this memory test interrupted learning after an initial encoding experience in order to test for early encoding differences and associate those differences with changes in decision-making. In a second experiment, we used fMRI to probe neural differences between the two list-length groups related to decision-making across learning and assessed subsequent memory retention. We found that a striatum-based system was associated with decision-making patterns when learning a longer list of items, while a medial cortical network was associated with patterns when learning a shorter list. Additionally, the hippocampus was exclusively active for the shorter list group. Altogether, these behavioral, computational, and imaging results provide evidence that multiple types of mnemonic representations contribute to experienced-based decision-making. Moreover, contextual and structural factors of the task and of prior decisions can influence what types of evidence are drawn upon during decision-making.

Social learning and associative processes: A synthesis.

Social learning is often considered different from asocial learning in both its characteristics and mechanisms. I presented pigeons with a concurrent discrimination task in which they received artificial social information, consisting of simple shapes that distributed themselves between two options similarly to how conspecifics might. Subjects in some conditions combined personal information about the two options with this social-like information, but subjects in conditions in which personal information was very reliable ignored the social cues, much like cases in which animals only choose to copy choices of others under certain conditions. I present a modification of a popular associative model of individual learning that can replicate these results, despite not distinguishing between social and asocial cues. The model suggests that the adaptive use of social information does not require the assumption of specifically social learning strategies, but may be driven by the overshadowing of less reliable asocial cues by more reliable social cues. (PsycINFO Database Record

The oil-rich alga Schizochytrium sp. as a dietary source of docosahexaenoic acid improves shape discrimination learning associated with visual processing in a canine model of senescence

Whole cell Schizochytrium sp. is a rich source of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) including docosahexaenoic acid (DHA), an important nutrient for brain health. Aged beagle dogs experienced on a visuospatial task of working memory, variable-delay delayed-non-matching-to-position were used to assess efficacy of DHA-rich microalgae based upon DHA wt% of total phospholipids and 8-iso-PGF2α concentrations in plasma, and performance on cognitive assessments of visual object discrimination, learning, and memory consolidation after 25 weeks on fortified diet.Improved DHA status (p<0.001) and initial learning of the protocols for visual and variable contrast discrimination (p<0.05), but not long-term recall of the concurrent discrimination task were observed in animals fed the algal-fortified diet. Overall, results were consistent with dried Schizochytrium sp. as a source of n-3 LCPUFA nutrition to support DHA status in large mammals, and healthy brain function in a canine model of senescence.

Asymmetry between excitatory and inhibitory learning.

Five experiments investigated how learning about the added feature in a feature-positive discrimination or feature-negative discrimination is related to the change in reinforcement rate that the feature signals. Rats were trained in a magazine-approach paradigm with 2 concurrent discriminations between A versus AX and B versus BY. In 2 experiments (1 and 3), X and Y signaled an increase of 0.3 in the probability of reinforcement, from 0.1 to 0.4 (A vs. AX), or from 0.6 to 0.9 (B vs. BY). After extended training, each session included probe test trials in which X and Y were presented alone (Experiment 1) or in compound with another excitatory conditional stimulus (CS), C (Experiment 3). There was no difference in response rate between the 2 types of test trial (X vs. Y; XC vs. YC), consistent with the fact that X and Y signaled the same absolute change in reinforcement. In Experiments 2 and 4, X and Y signaled a decrease of 0.3 in the probability of reinforcement, from 0.4 to 0.1 (A vs. AX) or from 0.9 to 0.6 (B vs. BY). Test trials in which X or Y was presented with C showed that X had greater inhibitory strength than Y, consistent with the fact that X signaled a larger relative change in reinforcement. This was confirmed in Experiment 5, in which X and Y had the same inhibitory strength on test after training in which they signaled the same relative change in reinforcement but different absolute changes (0.3 to 0.1 for A vs. AX; 0.9 to 0.3 for B vs. BY). The results show that excitatory conditioning is linearly related to the increase in reinforcement rate, whereas inhibitory learning is not linearly related to the decrease in reinforcement rate. Implications of this for theories of associative learning are discussed. (PsycINFO Database Record

Neural signatures of experience-based improvements in deterministic decision-making

Feedback about our choices is a crucial part of how we gather information and learn from our environment. It provides key information about decision experiences that can be used to optimize future choices. However, our understanding of the processes through which feedback translates into improved decision-making is lacking. Using neuroimaging (fMRI) and cognitive models of decision-making and learning, we examined the influence of feedback on multiple aspects of decision processes across learning. Subjects learned correct choices to a set of 50 word pairs across eight repetitions of a concurrent discrimination task. Behavioral measures were then analyzed with both a drift-diffusion model and a reinforcement learning model. Parameter values from each were then used as fMRI regressors to identify regions whose activity fluctuates with specific cognitive processes described by the models. The patterns of intersecting neural effects across models support two main inferences about the influence of feedback on decision-making. First, frontal, anterior insular, fusiform, and caudate nucleus regions behave like performance monitors, reflecting errors in performance predictions that signal the need for changes in control over decision-making. Second, temporoparietal, supplementary motor, and putamen regions behave like mnemonic storage sites, reflecting differences in learned item values that inform optimal decision choices. As information about optimal choices is accrued, these neural systems dynamically adjust, likely shifting the burden of decision processing from controlled performance monitoring to bottom-up, stimulus-driven choice selection. Collectively, the results provide a detailed perspective on the fundamental ability to use past experiences to improve future decisions.

Attention is required for the perceptual integration of action object pairs.

Previous studies have demonstrated that functionally related objects are perceptually grouped during visual identification if they are depicted as if interacting with each other (Green and Hummel in J Exp Psychol Hum Percept Perform 32(5):1107-1119, 2006). However, it is unclear whether this integration requires attention or occurs pre-attentively. Here, we used a divided-attention task with variable attentional load to address this question. Participants matched a word label to a target object that was immediately preceded by a briefly presented, task-irrelevant tool that was either functionally related or unrelated to the word label (e.g., axe | "log" or hammer | "log"). The tool was either positioned to interact with the target object or faced away from it. The amount of attention available to process the tool was manipulated by asking participants to make a concurrent perceptual discrimination of varying difficulty on a surrounding frame stimulus. The previously demonstrated advantage for the related-and-interacting condition was replicated under conditions of no or low attentional load. This benefit disappeared under high competing attentional load, indicating that attention is required to integrate functionally related objects together into a single perceptual unit.

Visual Hierarchical Processing and Lateralization of Cognitive Functions through Domestic Chicks' Eyes

Hierarchical stimuli have proven effective for investigating principles of visual organization in humans. A large body of evidence suggests that the analysis of the global forms precedes the analysis of the local forms in our species. Studies on lateralization also indicate that analytic and holistic encoding strategies are separated between the two hemispheres of the brain. This raises the question of whether precedence effects may reflect the activation of lateralized functions within the brain. Non-human animals have perceptual organization and functional lateralization that are comparable to that of humans. Here we trained the domestic chick in a concurrent discrimination task involving hierarchical stimuli. Then, we evaluated the animals for analytic and holistic encoding strategies in a series of transformational tests by relying on a monocular occlusion technique. A local precedence emerged in both the left and the right hemisphere, adding further evidence in favour of analytic processing in non-human animals.

Exercise enhances memory consolidation in the aging brain

Exercise has been shown to reduce age-related losses in cognitive function including learning and memory, but the mechanisms underlying this effect remain poorly understood. Memory formation occurs in stages that include an initial acquisition phase, an intermediate labile phase, and then a process of consolidation which leads to long-term memory formation. An effective way to examine the mechanism by which exercise improves memory is to introduce the intervention (exercise), post-acquisition, making it possible to selectively examine memory storage and consolidation. Accordingly we evaluated the effects of post-trial exercise (10 min on a treadmill) on memory consolidation in aged canines both right after, an hour after, and 24 h after acute exercise training in concurrent discrimination, object location memory (OLM), and novel object recognition tasks. Our study shows that post-trial exercise facilitates memory function by improving memory consolidation in aged animals in a time-dependent manner. The improvements were significant at 24 h post-exercise and not right after or 1 h after exercise. Aged animals were also tested following chronic exercise (10 min/day for 14 consecutive days) on OLM or till criterion were reached (for reversal learning task). We found improvements from a chronic exercise design in both the object location and reversal learning tasks. Our studies suggest that mechanisms to improve overall consolidation and cognitive function remain accessible even with progressing age and can be re-engaged by both acute and chronic exercise.

The effects of age on associative and rule-based causal learning and generalization.

We assessed how age influences associative and rule-based processes in causal learning using the Shanks and Darby (1998) concurrent patterning discrimination task. In Experiment 1, participants were divided into groups based on their learning performance after 6 blocks of training trials. High discrimination mastery young adults learned the patterning discrimination more rapidly and accurately than moderate mastery young adults. They were also more likely to induce the patterning rule and use this rule to generate predictions for novel cues, whereas moderate mastery young adults were more likely to use cue similarity as the basis for their predictions. Like moderate mastery young adults, older adults used similarity-based generalization for novel cues, but they did not achieve the same level of patterning discrimination. In Experiment 2, young and older adults were trained to the same learning criterion. Older adults again showed deficits in patterning discrimination and, in contrast to young adults, even when they reported awareness of the patterning rule, they used only similarity-based generalization in their predictions for novel cues. These findings suggest that it is important to consider how the ability to code or use cue representations interacts with the requirements of the causal learning task. In particular, age differences in causal learning seem to be greatest for tasks that require rapid coding of configural representations to control associative interference between similar cues. Configural coding may also be related to the success of rule-based processes in these types of learning tasks.

Similarity in form and function of the hippocampus in rodents, monkeys, and humans

We begin by describing an historical scientific debate in which the fundamental idea that species are related by evolutionary descent was challenged. The challenge was based on supposed neuroanatomical differences between humans and other primates with respect to a structure known then as the hippocampus minor. The debate took place in the early 1860 s, just after the publication of Darwin's famous book. We then recount the difficult road that was traveled to develop an animal model of human memory impairment, a matter that also turned on questions about similarities and differences between humans and other primates. We then describe how the insight that there are multiple memory systems helped to secure the animal model and how the animal model was ultimately used to identify the neuroanatomy of long-term declarative memory (sometimes termed explicit memory). Finally, we describe a challenge to the animal model and to cross-species comparisons by considering the case of the concurrent discrimination task, drawing on findings from humans and monkeys. We suggest that analysis of such cases, based on the understanding that there are multiple memory systems with different properties, has served to emphasize the similarities in memory function across mammalian species.

Intentional forgetting diminishes memory for continuous events

In a novel event method directed forgetting task, instructions to Remember (R) or Forget (F) were integrated throughout the presentation of four videos depicting common events (e.g., baking cookies). Participants responded more accurately to cued recall questions (E1) and true/false statements (E2-4) regarding R segments than F segments. This was true even when forced to attend to F segments by virtue of having to perform concurrent discrimination (E2) or conceptual segmentation (E3) tasks. The final experiment (E5) demonstrated a larger R >F difference for specific true/false statements (the woman added three cups of flour) than for general true/false statements (the woman added flour) suggesting that participants likely encoded and retained at least a general representation of the events they had intended to forget, even though this representation was not as specific as the representation of events they had intended to remember.

Effects of Selective Neonatal Amygdala Damage on Concurrent Discrimination Learning and Reinforcer Devaluation in Monkeys

ObjectivesThe amygdala is known to be a key neural structure in many neuropsychiatric disorders. Primarily known for its involvement in fear regulation, the amygdala also plays a critical role in appetitive flexible decision-making. Yet, its contribution to the development of flexible goal-directed behavior has not been thoroughly examined.DesignThe current study examined flexible decision-making abilities after neonatal amygdala lesions in nonhuman primates using a behavioral paradigm known to measure the flexible monitoring of goal-directed choices in rodents, monkeys, and humans.MethodRhesus monkeys of both sexes were divided into two groups, a sham-operated control group (N=4) and a group with neonatal neurotoxic amygdala lesions (N=5). Animals received the lesions at 1–2 weeks and were tested at both four and six years of age on a concurrent discrimination reinforcer devaluation task.ResultsAlthough neonatal amygdala damage spared learning stimulus-reward associations, it severely impaired the ability to flexibly shift object choices away from those items associated with devalued food rewards. The results were similar to those obtained in monkeys that had acquired the same lesions in adulthood.ConclusionsThus, the amygdala is critical for appetitive decision-making, and provide further evidence of little functional sparing after early amygdala insult. The findings are discussed in relation to other behavioral measures on the same animals and to clinical neuropsychiatric disorders.

A perceptual discrimination task results in greater facilitation of voluntary saccades in Parkinson's disease patients

Many studies have shown that Parkinson's disease (PD) affects not only the ability to generate voluntary saccades but also the ability to suppress reflexive saccades (hyper-reflexivity). To further investigate these apparently contradictory effects of PD on the saccade system we adapted a well-known dual-task paradigm (Deubel, 2008) to measure saccades with and without a peripheral discrimination task. Previously we reported that the concurrent performance of a perceptual discrimination task abnormally reduced the latencies of reflexive saccades in PD. Here we report the effects of the concurrent discrimination task on the generation of voluntary saccades in a PD and a control group. As expected, when saccades were performed without the discrimination task the PD group made voluntary saccades with longer latencies and smaller gain than the control group. The concurrent performance of the perceptual discrimination task facilitated the initiation of voluntary saccades in both groups, but, surprisingly, this facilitatory effect was stronger in the PD group than in the control group. In addition, in the PD group voluntary saccades were abnormally facilitated by the peripheral symbol-changes that occur during saccade planning in this paradigm. The results of this study may help to clarify apparently contradictory oculomotor abnormalities observed in PD.