Integration of anatomical and external response mappings explains crossing effects in tactile localization: A probabilistic modeling approach

To act upon a tactile stimulus its original skin-based, anatomical spatial code has to be transformed into an external, posture-dependent reference frame, a process known as tactile remapping. When the limbs are crossed, anatomical and external location codes are in conflict, leading to a decline in tactile localization accuracy. It is unknown whether this impairment originates from the integration of the resulting external localization response with the original, anatomical one or from a failure of tactile remapping in crossed postures. We fitted probabilistic models based on these diverging accounts to the data from three tactile localization experiments. Hand crossing disturbed tactile left–right location choices in all experiments. Furthermore, the size of these crossing effects was modulated by stimulus configuration and task instructions. The best model accounted for these results by integration of the external response mapping with the original, anatomical one, while applying identical integration weights for uncrossed and crossed postures. Thus, the model explained the data without assuming failures of remapping. Moreover, performance differences across tasks were accounted for by non-individual parameter adjustments, indicating that individual participants’ task adaptation results from one common functional mechanism. These results suggest that remapping is an automatic and accurate process, and that the observed localization impairments in touch result from a cognitively controlled integration process that combines anatomically and externally coded responses.     

Diverging Paths: Understanding Racial Differences in Civic Engagement Among White,African American,and Latina/o Adolescents Using Structural Equation Modeling

There is increasing concern about the large civic engagement gap between Whites and Latina/o and African American youth. Some suggest this may be because traditional models and measures of civic engagement may not be as applicable for youth from historically marginalized groups. With an urban sample of middle and high school‐age youth (n = 903, 52% female), we used structural equation modeling to identify differences in civic pathways between youth from different racial/ethnic backgrounds. We found significant differences between groups including much stronger relationships between exposure to democratic practices and civic self‐efficacy and knowledge for African American and Latina/o youth than for White youth and a stronger relationship between civic knowledge and future civic engagement for Whites and Latina/os than for African Americans. These findings suggest that educators and researchers interested need to take into account the diversity of youths' racial experiences when examining youth civic development.     

How motor practice shapes memory: retrieval but not extra study can cause forgetting

We investigated the retrieval specificity of retrieval-induced forgetting (RIF) of motor sequences. In two experiments, participants learned sequential finger movements, each consisting of the movement of two fingers of either the left or the right hand. In the learning phase, these motor sequences were graphically presented and were to be learned as responses to simultaneously presented letter stimuli. Subsequently, participants selectively practiced half the items of one hand. A final recall test then assessed memory for all initially learned items. We contrasted different kinds of selective practice with each other. Whereas retrieval practice required retrieving motor sequences in response to letter stimuli from the learning phase, extra study was an extension of the learning phase, that is, participants performed motor sequences in response to the same animation graphic display as in the learning phase again accompanied by the letter stimulus. All practice conditions strengthened the practiced items, but only retrieval practice resulted in RIF. Thus, the strengthening of items through practice did not suffice to induce forgetting of related motor sequences. Retrieval was a necessary component for practice to shape memory for body movements by impairing the subsequent recall of motor sequences that were related to the practiced motor sequences.     

Cognitive costs of encoding novel natural activities: Can “learning by doing” be distracting and deceptive?

Findings from action memory research suggest that the enactment of simple actions and naturalistic activities results in similar memory performance to that from their observation. However, little is known about potential differences between the conditions during the encoding of the to-be-studied actions and activities. We analysed the cognitive costs of encoding two novel naturalistic activities studied via enactment or via observation in four experiments. In addition to memory performance, we measured objective cognitive costs with a secondary task and subjective cognitive costs with repeated ratings of mental effort and estimates of general activity difficulty. Memory performance was comparable across study conditions throughout all experiments. The enactment of activities repeatedly resulted in slower reaction times in the secondary task than did observation, suggesting higher objective costs. In contrast, subjective costs were rated lower after enactment than after observation. Findings from a pantomimic enactment condition suggested that the low ratings of subjective costs after enactment represent a misinterpretation of task demands. Our findings imply that the widespread belief about “learning by doing” as an easy way of learning does not stem from an actual advantage in memory performance, but rather from continuous feedback about one's performance resulting from enactment.     

Associative symmetry versus independent associations in the memory for object-location associations

The formation of associations between objects and locations is a vital aspect of episodic memory. More specifically, remembering the location where one experienced an object and, vice versa, the object one encountered at a specific location are both important elements for the memory of an event. Whether episodic associations are holistic representations of individual components or whether there are unidirectional, separately modifiable connections between them has been investigated nearly exclusively using verbal stimuli. A preliminary conclusion concerning this controversy is that verbal associations are, at least, highly correlated (M. J. Kahana, 2002). This theoretical debate, which in the past has undergone a major empirical effort, is still of relevance for the concurrent global matching models of associative memory (S. E. Clark & S. D. Gronlund, 1996). The authors used variations of a novel object-location learning paradigm to complement the accumulated evidence regarding the nature of episodic associations.     

Mind-reading without the scanner: Behavioural decoding of working memory content

ABSTRACT

Sophisticated machine learning algorithms have been successfully applied to functional neuroimaging data in order to characterize internal cognitive states. But is it possible to “mind-read” without the scanner? Capitalizing on the robust finding that the contents of working memory guide visual attention toward memory-matching objects, we trained a multivariate pattern classifier on behavioural indices of attentional guidance. Working memory representations were successfully decoded from behaviour alone, both within and between individuals. The current study provides a proof-of-concept for applying machine learning techniques to simple behavioural outputs (e.g., response times) in order to decode information about specific internal cognitive states.     

The importance of response type to the relationship between temporal order and numerical magnitude

Time, number, and space may be represented in the brain by a common set of cognitive/neural mechanisms. In support of this conjecture, Schwarz and Eiselt (Journal of Experimental Psychology: Human Perception and Performance, 35, 989-1004, 2009) found that numerically smaller digits were perceived to occur earlier than larger digits, and they concluded that this difference reflected faster processing of smaller numbers. This difference, however, could have been related to a response bias, whereby participants map responses of "which first" onto the "first" number along the mental number line. In Experiment 1, participants made temporal order judgements between digits presented to the left or to the right. The point of subjective simultaneity was shifted so that the 9 had to be presented before the 2 in order for simultaneity to be perceived. This difference could reflect either faster processing of the 2 or a response bias. Experiments 2a and 2b eliminated response biases by using simultaneity judgements, which have no logical stimulus mapping. Both of the latter experiments established that the 2 was not processed faster than the 9. Although the present results relate specifically to numerical magnitude and temporal order associations, they also have broader implications. Other studies have reported associations between dimensions such as size, duration, and number and have attributed these to parietal mechanisms. Such associations, however, may also be an artefact of response biases.     

Attractors and perceptual field dynamics of homogeneous stimulus areas

Summary The phenomenon of the wandering point on a blank sheet of paper in serial reproductions is the starting point of an investigation of the perceptual field structure of homogeneous stimulus areas; 609 stimulus points distributed regularly in 21 rows and 29 columns on a DIN A4 sheet were presented successively to 10 subjects and had to be reproduced immediately afterwards in order to establish empirical vector fields. These were subjected to vector-analytic procedures. A method for the decomposition of the measured vector fields into partitions from gradient potentials and circulation potentials is demonstrated. The gradient potentials of the empirical vector fields revealed a highly regular structure with four point attractors near the corners of the sheet. A model calculation of the wandering point in this potential landscape showed results comparable to the empirical phenomenon. The results are discussed in favor of Gestalt theory and against direct perception.     

Positive mental health moderates the association between depression and suicide ideation: A longitudinal study

Background/Objective: Depression and suicide ideation regularly occur together. Yet, little is known about factors that buffer individuals against the development of suicide ideation. The present study investigated, whether positive mental health buffers the association between depression and suicide ideation in a longitudinal study design. Methods: A total of 207 German students (70.3% female; age: M = 26.04, SD = 5.33) were assessed at a baseline evaluation and again twelve months later. Data were collected using self-report questionnaires. Linear hierarchical regression analysis was used to analyze the data. Positive mental health was considered to moderate the impact of depression on suicide ideation – controlling for age and gender. Results: Positive mental health was shown to moderate the impact of depression on suicide ideation: in those students who reported higher levels of positive mental health, depression severity showed no association with suicide ideation over time. Conclusion: Positive mental health seems to confer resilience and should be taken into account, when assessing individuals for suicide risk.