Discover the most talked about and latest scientific content & concepts.

Journal: International journal of psychophysiology : official journal of the International Organization of Psychophysiology


A binaural beat can be produced by presenting two tones of a differing frequency, one to each ear. Such auditory stimulation has been suggested to influence behaviour and cognition via the process of cortical entrainment. However, research so far has only shown the frequency following responses in the traditional EEG frequency ranges of delta, theta and gamma. Hence a primary aim of this research was to ascertain whether it would be possible to produce clear changes in the EEG in either the alpha or beta frequency ranges. Such changes, if possible, would have a number of important implications as well as potential applications. A secondary goal was to track any observable changes in the EEG throughout the entrainment epoch to gain some insight into the nature of the entrainment effects on any changes in an effort to identify more effective entrainment regimes. Twenty two healthy participants were recruited and randomly allocated to one of two groups, each of which was exposed to a distinct binaural beat frequency for ten 1-minute epochs. The first group listened to an alpha binaural beat of 10Hz and the second to a beta binaural beat of 20Hz. EEG was recorded from the left and right temporal regions during pre-exposure baselines, stimulus exposure epochs and post-exposure baselines. Analysis of changes in broad-band and narrow-band amplitudes, and frequency showed no effect of binaural beat frequency eliciting a frequency following effect in the EEG. Possible mediating factors are discussed and a number of recommendations are made regarding future studies, exploring entrainment effects from a binaural beat presentation.

Concepts: Effectiveness, Electroencephalography, Acoustics, Sound, Meditation, Binaural beats, Neurofeedback, Mind machine


Heart rate variability (HRV) is widely used to assess autonomic nervous system (ANS) function. It is traditionally collected from a dedicated laboratory electrocardiograph (ECG). This presents a barrier to collecting the large samples necessary to maintain the statistical power of between-subject psychophysiological comparisons. An alternative to ECG involves an optical pulse sensor or photoplethysmograph run from a smartphone or similar portable device: smartphone pulse rate variability (SPRV). Experiment 1 determined the simultaneous accuracy between ECG and SPRV systems in n=10 participants at rest. Raw SPRV values showed a consistent positive bias, which was successfully attenuated with correction. Experiment 2 tested an additional n=10 participants at rest, during attentional load, and during mild stress (exercise). Accuracy was maintained, but slightly attenuated during exercise. The best correction method maintained an accuracy of +/-2% for low-frequency spectral power, and +/- 5% for high-frequency spectral power over all points. Thus, the SPRV system records a pulse-to-pulse approximation of an ECG-derived heart rate series that is sufficiently accurately to perform time- and frequency-domain analysis of its variability, as well as accurately reflecting change in autonomic output provided by typical psychophysiological stimuli. This represents a novel method by which an accurate approximation of HRV may be collected for large-sample or naturalistic cardiac psychophysiological research.

Concepts: Sample size, Cardiology, Heart, Pulse, Heart rate, Autonomic nervous system, Radial artery, Heart rate monitor


Cognitive enhancement is a popular topic, attracting attention both from the general public and the scientific research community. Higher cognitive functions are involved in various aspects of everyday life and have been associated with manifest behavioral and psychiatric mental impairments when deteriorated. The improvement of these so-called executive functions (EFs) is of high individual, social, and economic relevance. This review provides a synopsis of two lines of research, investigating the enhancement of capabilities in executive functioning: a) computerized behavioral trainings, and b) approaches for direct neuromodulation (neurofeedback and transcranial electrostimulation). Task switching, memory updating, response inhibition, and dual task performance are addressed in terms of cognitive functions. It has been shown that behavioral cognitive training leads to enhanced performance in task switching, memory updating, and dual tasks. Similarly, direct neurocognitive modulation of brain regions that are crucially involved in specific EFs also leads to behavioral benefits in response inhibition, task switching, and memory updating. Response inhibition performance has been shown to be improved by neurostimulation of the right inferior frontal cortex, whereas neurostimulation of the dorsolateral prefrontal cortex exerts effects on task switching and memory updating. Due to a lack of consistency in experimental methods and findings, a comparison of different training approaches concerning their effectiveness is not yet possible. So far, current data suggest that training gains may indeed generalize to untrained tasks aiming at the same cognitive process, as well as across cognitive domains within executive control.

Concepts: Scientific method, Psychology, Brain, Cognition, Cerebrum, Neuropsychology, Frontal lobe, Working memory


This research examined cultural differences in experiential and cardiovascular outcomes of three anger regulation strategies (expression, suppression and reappraisal).


Stable personality traits have long been presumed to have biological substrates, although the evidence relating personality to biological stress reactivity is inconclusive. The present study examined, in a large middle aged cohort (N = 352), the relationship between key personality traits and both cortisol and cardiovascular reactions to acute psychological stress. Salivary cortisol and cardiovascular activity were measured at rest and in response to a psychological stress protocol comprising 5-minutes each of a Stroop task, mirror tracing, and a speech task. Participants subsequently completed the Big Five Inventory to assess neuroticism, agreeableness, openness to experience, extraversion, and conscientiousness. Those with higher neuroticism scores exhibited smaller cortisol and cardiovascular stress reactions, whereas participants who were less agreeable and less open had smaller cortisol and cardiac reactions to stress. These associations remained statistically significant following adjustment for a range of potential confounding variables. Thus, a negative personality disposition would appear to be linked to diminished stress reactivity. These findings further support a growing body of evidence which suggests that blunted stress reactivity may be maladaptive.

Concepts: Psychology, Personality psychology, Neuroticism, Big Five personality traits, Trait theory, Personality traits, Openness to experience, Agreeableness


Nighttime fear is a phenomenon in which people feel more afraid of threats at night. Despite the vast amount of psychological research on nighttime fear, previous researchers have not accurately distinguished between “night” and “darkness”, both of which play important roles in nighttime fear. We collected physiological (skin conductance response and heart rate) and psychological (self-report) data simultaneously to investigate the effects of “night” and “darkness” on fearful feelings and whether these effects were moderated by the mode of stimulus delivery (i.e., visual or auditory). Specifically, two tasks were employed in which time (day vs. night), illumination (light vs. darkness) and stimulus type (fearful vs. neutral) were manipulated. Participants (n=128) were exposed to visual and auditory oddball tasks consisting of fearful and neutral stimuli. The results indicated that there were significant increases in fear responses at night, and the difference between day and night was significant for fear stimuli but not for neutral events. Furthermore, these effects were consistent over different sensory modalities (visual and auditory). The results of this study underscore the importance of the day-night cycle in fear-related information processing and suggest that further attention needs to be paid to the influence of the biological circadian rhythm on these processes. The current findings could inform a deeper understanding of anxiety and fear-related disorders, and thus, we invite future studies to illuminate the underlying neurobiological mechanisms therein.

Concepts: Anxiety, Psychology, Sleep, Sensory system, Emotion, Anxiety disorder, Fear, Feeling


Palmatier and Rovner (2014) discussed the possible interplay of two major methods of polygraph examination, the Comparison Question Test (CQT) and the Concealed Information Test (CIT). In this comment, we argue that such an attempt overlooks fundamental differences between the two methods. Specifically, both methods differ in their criterion variables; detecting deception versus detecting memory traces. This difference can lead to a different evaluation concerning their outcomes within a forensic context. However, Palmatier and Rovner’s (2014) attempt may blur the distinction between the two methods. Furthermore, at least for the present, it is difficult to give a unified explanation of physiological responses in the CQT and CIT based on the preliminary process theory of the orienting response. In sum, Palmatier and Rovner’s (2014) paper may add further confusion to the research and practice of polygraph testing. Additionally, their paper has no relevance to the current practice of Japanese polygraph examination, because Japanese law enforcement uses only the CIT for memory detection in real-life criminal investigations.

Concepts: Present, Physiology, Difference, Differences, Japan, Police, Government of Japan, Polygraph


Palmatier and Rovner (2014) suggested that the Preliminary Process Theory (PPT) is a plausible theoretical account for explaining the rationale underlying two major polygraph tests, the Comparison Question Test (CQT) and the Concealed Information Test (CIT). To support their suggestion they claimed that both tests detect deception while relying on orienting responses. This approach is critically discussed. It was concluded that application of current scientific theories to polygraph diagnostic procedures should be done separately for the CIT and for the CQT. Finally, a call was extended for more research on unanswered questions in polygraph testing.

Concepts: Scientific method, Greek loanwords, Science, Experiment, Philosophy of science, Theory, Theories, Polygraph


The term “polygraph test,” particularly in a forensic context, is used generally to describe diagnostic procedures using a polygraph instrument to assess credibility. Polygraph testing has been subject to greater scrutiny, debate, and empirical study than many other forensic techniques. It has been repeatedly demonstrated that, when used properly, the polygraph testing process functions with a high degree of predictive (criterion) validity. However, advocates have failed to address, in a substantive manner, the primary objection often cited by opponents that the polygraph procedure most used in applied day-to-day contexts, that is, comparison question testing (CQT), is atheoretical and lacking construct validity. A review of the available research literature, including that from the neurosciences, psychophysiology, and other relevant disciplines, coupled with an intimate understanding of two commonly used polygraph procedures, the context in which they are used, and the scientific method, strongly suggest that such claims are no longer true, nor warranted. Here, we discuss the interplay of the two most advocated polygraph procedures, the CQT and CIT (Concealed Information Testing), with Preliminary Process Theory (PPT), contemporary writings on memory and other contributions from the research literature relevant to the instrumental assessment of credibility. We conclude that the available scientific evidence establishes not only a plausible theoretical construct that strengthens the practical application of the polygraph process in forensic and other settings, but also concurrently provides directions for future research by scientists interested in the applied assessment of credibility.

Concepts: Scientific method, Science, Research, Psychometrics, Empiricism, Empirical, Theory, Pseudoscience


Low voltage EEG (LVEEG) is a heritable phenotype that differs depending on ancestral heritage, yet its impact on brain networks and cognition remain relatively unexplored. In this study we assessed energy and task related phase locking of event-related oscillation (EROs), behavioral responses, measures of IQ and personality, and expected responses to alcohol in a large sample of individuals with LVEEG compared to those with higher voltage variants. Participants (n=762) were recruited from a Native American community and completed a diagnostic interview, the Quick Test, the Subjective High Assessment scale (SHAS-E) and the Maudsley Personality Inventory. Clinical and spectral analyzed EEGs were collected for determination of the presence of a LVEEG variant. EROs were generated using a facial expression recognition task. Participants with LVEEG (n=451) were significantly more likely to be older, married and have higher degrees of Native American heritage but did not differ in gender, income or education. Individuals with LVEEG were also found to have decreased energy in their alpha EROs, increased phase locking between stimulus trials, and increased phase-locking between cortical brain areas. No significant differences in the cognitive tests, personality variables or alcohol dependence or anxiety diagnoses were found, however, individuals with LVEEG did report a larger number of drinks ever consumed in a 24-hr period and a less intense expected response to alcohol. These data suggest that alpha power in the resting EEG is highly associated with energy and cortical connectivity measures generated by event-related stimuli, as well as potentially increased risk for alcohol use.

Concepts: Psychology, Brain, Cognitive psychology, Alcoholism, Cognition, Oscillation, Alcohol abuse, Native Americans in the United States