The effect of 5 nights of sleep restriction on empathic propensity.

Literature supports the existence of a significant relationship between sleep quality/quantity and empathy. However, empathic ability and empathic propensity are distinct constructs. Expression of empathic propensity depends on the subjective cognitive costs attributed to the empathic experience. Studies on the effects of the experimental reduction in sleep duration on empathic behaviour are still lacking. Therefore, we investigated the consequences of 5 consecutive nights of sleep restriction on empathic propensity. A total of 42 university students (mean [SEM] age 24.09 [0.65] years; 22 females) underwent a cross-over design consisting of 5 consecutive nights of regular sleep and 5 consecutive nights of sleep restriction with a maximum of 5 hr sleep/night. After each condition, all participants were evaluated using the Empathy Selection Task, a new test assessing the motivated avoidance of empathy for its associated cognitive costs. The results showed different effects of sleep restriction depending on the habitual way of responding in the empathic context. Participants with baseline high levels of empathic propensity reduced their empathic propensity after prolonged sleep restriction. Differently, participants who tended to avoid empathising already in the habitual sleep condition maintained their empathic behaviour unchanged after sleep curtailment. In conclusion, inter-individual variability should be taken into account when evaluating the effects of sleep restriction on empathic propensity. People with habitual higher tendency to empathise could choose to avoid empathic experience following several consecutive nights of inadequate sleep.

On the Cost of Detection Response Task Performance on Cognitive Load.

OBJECTIVE: This study investigates the cost of detection response task performance on cognitive load. BACKGROUND: Measuring system operator's cognitive load is a foremost challenge in human factors and ergonomics. The detection response task is a standardized measure of cognitive load. It is hypothesized that, given its simple reaction time structure, it has no cost on cognitive load. We set out to test this hypothesis by utilizing pupil diameter as an alternative metric of cognitive load. METHOD: Twenty-eight volunteers completed one of four experimental tasks with increasing levels of cognitive demand (control, 0-back, 1-back, and 2-back) with or without concurrent DRT performance. Pupil diameter was selected as nonintrusive metric of cognitive load. Self-reported workload was also recorded. RESULTS: A significant main effect of DRT presence was found for pupil diameter and self-reported workload. Larger pupil diameter was found when the n-back task was performed concurrently with the DRT, compared to no-DRT conditions. Consistent results were found for mental workload ratings and n-back performance. CONCLUSION: Results indicate that DRT performance produced an added cost on cognitive load. The magnitude of the change in pupil diameter was comparable to that observed when transitioning from a condition of low task load to one where the 2-back was performed. The significant increase in cognitive load accompanying DRT performance was also reflected in higher self-reported workload. APPLICATION: DRT is a valuable tool to measure operator's cognitive load. However, these results advise caution when discounting it as cost-free metric with no added burden on operator's cognitive resources.

Biases and Variability from Costly Bayesian Inference.

When humans infer underlying probabilities from stochastic observations, they exhibit biases and variability that cannot be explained on the basis of sound, Bayesian manipulations of probability. This is especially salient when beliefs are updated as a function of sequential observations. We introduce a theoretical framework in which biases and variability emerge from a trade-off between Bayesian inference and the cognitive cost of carrying out probabilistic computations. We consider two forms of the cost: a precision cost and an unpredictability cost; these penalize beliefs that are less entropic and less deterministic, respectively. We apply our framework to the case of a Bernoulli variable: the bias of a coin is inferred from a sequence of coin flips. Theoretical predictions are qualitatively different depending on the form of the cost. A precision cost induces overestimation of small probabilities, on average, and a limited memory of past observations, and, consequently, a fluctuating bias. An unpredictability cost induces underestimation of small probabilities and a fixed bias that remains appreciable even for nearly unbiased observations. The case of a fair (equiprobable) coin, however, is singular, with non-trivial and slow fluctuations in the inferred bias. The proposed framework of costly Bayesian inference illustrates the richness of a 'resource-rational' (or 'bounded-rational') picture of seemingly irrational human cognition.

Shifts of the point-of-change can be attributed to a lower mechanical cost of motor execution.

In a previous study on hand selection in a sequential reaching task, the authors showed a shift of the point-of-change (POC) to the left of the midline. This implies that participants conducted a number of contralateral reaches with their dominant, right hand. Contralateral movements have longer planning and execution times and a lower precision. In the current study, we asked whether lower mechanical costs of motor execution or lower cognitive costs of motor planning compensated for these disadvantages. Theories on hemispheric differences postulate lower mechanical costs in the dominant hemisphere and lower cognitive costs in the left hemisphere (independent of handedness). In right-handed participants, both factors act agonistically to reduce the total cost of right-handed reaches. To distinguish between the cost factors, we had left- and right-hand-dominant participants execute a sequential, unimanual reaching task. Results showed a left-shift of the POC in the right-handed and a right-shift in the left-handed group. Both shifts were similar in magnitude. These findings indicate that only the mechanical cost of motor execution compensates for the disadvantages of the contralateral reaches, while the cognitive cost of motor planning is irrelevant for the POC shift.

Comparing costs in time-based and event-based prospective memory.

Although much recent research has focused on event-based prospective memory (PM), fewer studies have compared event- and time-based PM. In the current study, two experiments were conducted to directly compare ongoing task costs of focal and non-focal event-based tasks with a time-based task. In the second experiment, an external reminder of the task was present to test whether this reduced the cost of the time-based task. PM accuracy was significantly greater for the focal conditions, as predicted. Response times (RT) were highest in the non-focal tasks, with similar RTs in the focal and time-based tasks. Clock check frequency was significantly related to making a PM response in the time-based task, with clock checks increasing as the 7 min target time approached. While time-based tasks may be more difficult to complete, they do not seem to result in the speed cost to an ongoing task that non-focal PM tasks do.

Cognitive costs of motor planning do not differ between pointing and grasping in a sequential task.

Neurophysiologic studies have shown differences in brain activation between pointing and grasping movements. We asked whether these two movement types would differ in their cognitive costs of motor planning. To this end, we designed a sequential, continuous posture selection task, suitable to investigate pointing and grasping movements to identical target locations. Participants had to open a column of drawers or point to a column of targets in ascending and descending progression. The global hand pro/supination at the moment of drawer/target contact was measured. The size of the motor hysteresis effect, i.e., the persistence to a former posture, was used as a proxy for the cognitive cost of motor planning. A larger hysteresis effect equals higher cognitive cost. Both motor tasks had similar costs of motor planning, but a larger range of motion was found for the grasping movements.

Cognitive enhancement or cognitive cost: trait-specific outcomes of brain stimulation in the case of mathematics anxiety.

The surge in noninvasive brain stimulation studies investigating cognitive enhancement has neglected the effect of interindividual differences, such as traits, on stimulation outcomes. Using the case of mathematics anxiety in a sample of healthy human participants in a placebo-controlled, double-blind, crossover experiment, we show that identical transcranial direct current stimulation (tDCS) exerts opposite behavioral and physiological effects depending on individual trait levels. Mathematics anxiety is the negative emotional response elicited by numerical tasks, impairing mathematical achievement. tDCS was applied to the dorsolateral prefrontal cortex, a frequent target for modulating emotional regulation. It improved reaction times on simple arithmetic decisions and decreased cortisol concentrations (a biomarker of stress) in high mathematics anxiety individuals. In contrast, tDCS impaired reaction times for low mathematics anxiety individuals and prevented a decrease in cortisol concentration compared with sham stimulation. Both groups showed a tDCS-induced side effect-impaired executive control in a flanker task-a cognitive function subserved by the stimulated region. These behavioral and physiological double dissociations have implications for brain stimulation research by highlighting the role of individual traits in experimental findings. Brain stimulation clearly does not produce uniform benefits, even applied in the same configuration during the same tasks, but may interact with traits to produce markedly opposed outcomes.

Cognitive Development as a Piece of the Language Learning Puzzle.

Why do children learn language more easily than adults do? This puzzle has fascinated cognitive and language scientists for decades. In the present letter, we approach the language learning puzzle from a cognitive perspective that is inspired by evidence from the perceptual and motor learning literature. Neuroscientific studies show that two memory systems in the brain are involved in human learning: an early implicit procedural memory system and a late-developing cognitive or declarative memory system. We argue that higher cognitive development constrains implicit statistical learning processes that are essential for learning patterns and regularities in languages, that is, the adult cognitive architecture has a cost. This is supported by experimental evidence showing that acquisition of implicit linguistic knowledge is enhanced under cognitive depletion in adults. More research is needed to test the cognitive cost hypothesis as it could partly solve the language learning puzzle.

A Clinical Paradigm for Listening Effort Assessment in Middle-Aged Listeners.

Listening effort (LE) has been known to characterize speech recognition in noise regardless of hearing sensitivity and age. Whereas the behavioral measure of dual-task paradigm effectively manifests the cognitive cost that listeners exert when processing speech in background noise, there is no consensus as to a clinical procedure that might best express LE. In order to assess the cognitive load underlying speech recognition in noise and promote counselling for coping strategies, a feasible clinical paradigm is warranted. The ecological validity of such a paradigm might best be demonstrated in middle-aged adults, exhibiting intact hearing sensitivity on one hand, however, experiencing difficulties in degraded listening conditions, unaware of the implicated cognitive cost of speech recognition in noise. To this end, we constructed a dual-task paradigm that consists of a primary task of sentences-in-noise recognition and a secondary task of simple visual colored-shape matching. Research objective was to develop a clinical paradigm for the assessment of LE in middle-aged adults. Participants were 17 middle-aged adults (mean age of 52.81 years) and 23 young adults (mean age of 24.90 years). All participants had normal hearing according to age. Speech stimuli consisted of the Hebrew Matrix sentences in noise test. SRTn was obtained for 80% correct identification. Visual stimuli were colored geometric shapes. Outcome measures were obtained initially for each task separately, to establish performance ability, and then obtained simultaneously. Reaction time and accuracy in the secondary task were the defined metrics for LE. Results: LE was indicated for both groups, however, was more pronounced in the middle-aged, manifested in the visual accuracy and reaction time metrics. Both groups maintained the 80% correct recognition-in-noise in the dual-task, however, the middle-aged group necessitated a better SNR of 1.4dB than the normal hearing group. Moreover, the middle-aged group was taxed in a greater prolongation of reaction time, in order to uphold the correct recognition. Conclusion: a dual-task paradigm consisting of sentences-in-noise primary task combined with a simple secondary task successfully showed different manifestations of LE in middle-aged adults compared to young adults, thus approximating the use of such a paradigm in a clinical setting.

Conceptual Similarity and Communicative Need Shape Colexification: An Experimental Study.

Colexification refers to the phenomenon of multiple meanings sharing one word in a language. Cross-linguistic lexification patterns have been shown to be largely predictable, as similar concepts are often colexified. We test a recent claim that, beyond this general tendency, communicative needs play an important role in shaping colexification patterns. We approach this question by means of a series of human experiments, using an artificial language communication game paradigm. Our results across four experiments match the previous cross-linguistic findings: all other things being equal, speakers do prefer to colexify similar concepts. However, we also find evidence supporting the communicative need hypothesis: when faced with a frequent need to distinguish similar pairs of meanings, speakadjust their colexification preferences to maintain communicative efficiency and avoid colexifying those similar meanings which need to be distinguished in communication. This research provides further evidence to support the argument that languages are shaped by the needs and preferences of their speakers.

Age-related differences in brain activation during working memory updating: An fMRI study.

Recent neuroimaging studies have reported an age-related reduction in brain activations in response to working memory load in task-sensitive brain regions. The current fMRI study investigated the age-related differences in brain activations of the updating mechanism in working memory, which was not investigated in previous studies. With a hybrid block/event-related design, this study was able to examine changes in BOLD signals (i.e., neuromodulation) to increase in updating, a type of cognitive control that is understudied. Older adults were separated into young-old and old-old cohorts to examine whether, within healthy aging, the neuromodulation to cognitive control decreases with age. Our results show that younger adults activate left precentral gyrus and right cerebellum more during trials that require updating than trials that do not require updating. Although older adults showed reduced neuromodulation in these two regions, the old-old cohort failed to show any significant neuromodulation in response to updating. Moreover, older adults not only showed reduced suppressions of the default mode network (DMN) regions during the task, they also overactivated some of the DMN regions, esp. the old-old, when compared to the younger adults. Older adults also showed overactivations in a region (right precentral gyrus) that is contralateral to a task-sensitive region that was activated in the younger adults during updating. Brain-behavior correlations suggest that age-related overactivations of these DMN regions and the right precentral gyrus are maladaptive to their performance. Our results suggest that not only the neuromodulation in response to updating demands is diminished in healthy aging, older adults also show maladaptive increases in activations of task-irrelevant regions and reduced hemispheric specificity during updating. These effects are most pronounced in old-old cohort, compared to young-old, suggesting that age-related declines in neuromodulation during cognitive control is more pronounced in older cohorts within healthy aging.

Positive and Detached Reappraisal of Threatening Music in Younger and Older Adults.

Past empirical studies have suggested that older adults preferentially use gaze-based mood regulation to lessen their negative experiences while watching an emotional scene. This preference for a low cognitively demanding regulatory strategy leaves open the question of whether the effortful processing of a more cognitively demanding reappraisal task is really spared from the general age-related decline. Because it does not allow perceptual attention to be redirected away from the emotional source, music provides an ideal way to address this question. The goal of our study was to examine the affective, behavioral, physiological, and cognitive outcomes of positive and detached reappraisal in response to negative musical emotion in younger and older adults. Participants first simply listened to a series of threatening musical excerpts and were then instructed to either positively reappraise or to detach themselves from the emotion elicited by music. Findings showed that, when instructed to simply listen to threatening music, older adults reported a more positive feeling associated with a smaller SCL in comparison with their younger counterparts. When implementing positive and detached reappraisal, participants showed more positive and more aroused emotional experiences, whatever the age group. We also found that the instruction to intentionally reappraise negative emotions results in a lesser cognitive cost for older adults in comparison with younger adults. Taken together, these data suggest that, compared to younger adults, older adults engage in spontaneous downregulation of negative affect and successfully implement downregulation instructions. This extends previous findings and brings compelling evidence that, even when auditory attention cannot be redirected away from the emotional source, older adults are still more effective at regulating emotions. Taking into account the age-associated decline in executive functioning, our results suggest that the working memory task could have distracted older adults from the reminiscences of the threat-evoking music, thus resulting in an emotional downregulation. Hence, even if they were instructed to implement reappraisal strategies, older adults might prefer distraction over engagement in reappraisal. This is congruent with the idea that, although getting older, people are more likely to be distracted from a negative source of emotion to maintain their well-being.

The Cost of Prospective Memory in Children: The Role of Cue Focality.

Prospective memory (PM) is an essential ability in daily life, since it involves remembering to perform an intention. While PM largely develops during childhood and adolescence, its underlying mechanisms are still poorly understood. In general, age differences in PM have been found with tasks in which the prospective cues are not part of the ongoing activity (non-focal PM tasks). In the present study, we evaluated the cognitive cost produced by a PM task over the ongoing activity by comparing the performance of a single-task condition with that of an ongoing activity condition involving a prospective intention. Specifically, to determine the impact of cue focality on performance as a function of age, we tested two groups of children (6 and 11 years old) in three experimental conditions: single, focal and non-focal prospective cues. In the single-task condition, children were only asked to perform the ongoing task (to categorize images as animal or non-animal). In the focal condition, in addition to performing the ongoing activity, participants were asked to press different keys whenever the image appearing on the screen was a kite or a ball. In the non-focal condition, children were to press the keys if the color of the frame of the screen changed to magenta or gray. Although reaction times were greater for the non-focal conditions in both age groups, the results showed worse performance on the ongoing activity for both the focal and the non-focal conditions (relative to the single-task condition) in the younger children. This difference was less pronounced in older children so that response times for focal and non-focal cues differed from the single condition, but the difference in performance between focal and single task conditions was not reliable. These findings, which are partly in line with the dual process framework (McDaniel et al., 2015), suggest that while non-focal prospective cues compromise attentional control in younger and older children, focal cues seem to rely on less effortful processes in older children.