Temporal and non-temporal sensory discrimination and their predictions of capacity- and speed-related aspects of psychometric intelligence

Intelligence Predicts Sensory Discrimination Ability but Not Implicit Reward Learning

Abstract. Previous research has made use of sensory discrimination tasks that incorporate differential reinforcement schedules as a method for measuring individual differences in implicit reward learning. One such task was popularized by Pizzagalli and colleagues (2005) with the intent of behaviorally assessing anhedonia and reward sensitivity. Various studies have examined implicit reward learning in relation to clinical symptoms and personality traits, including anhedonia, depression, and Extraversion. Despite extensive use of these tasks, they have not been extensively examined in relation to intelligence, which affects performance on many cognitive tasks. Other research suggests positive associations of intelligence with sensory discrimination ability. The present study utilized a probabilistic reward task in a large community sample to determine the relations among IQ, sensory discrimination ability, and implicit reward learning. Participants ( N = 298) completed a sensory discrimination task, as well as an IQ test. IQ was not associated with participants’ levels of implicit reward learning but was positively associated with sensory discrimination ability. These findings provide a further understanding of the complex relations among implicit learning, sensory discrimination ability, and intelligence.

The electrophysiological masking level difference: effects of age and mediation of hearing and cognition

OBJECTIVE

Evaluate the conceptual framework that age effects on the electrophysiological binaural masking level difference (MLD) are partially mediated by age-related hearing loss and/or global cognitive function via mediation analysis.

DESIGN

Participants underwent a series of audiometric tests. The MLD was measured via cortical auditory evoked potentials using a speech stimulus (/ɑ/) in speech-weighted background noise. We used mediation analyses to determine the total effect, natural direct effects, and natural indirect effects, which are displayed as regression coefficients ([95% CI]; p value).

STUDY SAMPLE

Twenty-eight individuals aged 19-87 years (mean [SD]: 53.3 [25.2]), recruited from the community.

RESULTS

Older age had a significant total effect on the MLD (-0.69 [95% CI: -0.96, -0.45]; p < 0.01). Neither pure tone average (-0.11 [95% CI: -0.43, 0.24; p = 0.54] nor global cognitive function (-0.02 [95% CI: -0.13, 0.02]; p = 0.55) mediated the relationship of age and the MLD and effect sizes were small. Results were insensitive to use of alternative hearing measures or inclusion of interaction terms.

CONCLUSIONS

The electrophysiological MLD may be an age-sensitive measure of binaural temporal processing that is minimally affected by age-related hearing loss and global cognitive function.

Conditioned Placebo- and Nocebo-Like Effects in Adolescents: The Role of Conscious Awareness, Sensory Discrimination, and Executive Function

Background: Conditioning is a key mechanism of placebo and nocebo effects in adults. Little is known about the underlying mechanisms of placebo and nocebo effects in youth and how they might be influenced by conscious awareness and cognitive abilities. In this study, the role of conditioning on thermal perception in youth was investigated. Methods: Differences in thermal ratings were assessed in response to consciously and non-consciously perceived cues that were conditioned to either low or high heat. Furthermore, we tested whether executive function mediates the effect of conditioning on thermal perception. Thirty-five high-school students (14-17 years) completed an executive function task and underwent a sensory perception paradigm. In a conditioning phase, two distinct neutral faces (conditioned cues) were coupled to either a low or a high temperature stimulus delivered to participants' forearms. In a testing phase, the conditioned cues, and novel faces (non-conditioned control cues), were paired with identical moderate thermal stimuli. In this testing phase, for half of the participants cues were presented consciously (supraliminally) and for the other half non-consciously (subliminally). Results: We found a significant main effect of cue type on thermal ratings (p = 0.003) in spite of identical heat being administered following all cues. Post-hoc analyses indicated that the nocebo-like effect (conditioned high cue compared to control) was significant (p = 0.027); the placebo-like effect (conditioned low cue compared to control) was non-significant. No difference between cues presented supra- vs. subliminally and no significant interaction effects were found. The association between sensory discrimination and the magnitude of the nocebo-like effect was mediated by executive function. Conclusions: To our best knowledge, this is the first study establishing a relationship between thermal perception, nocebo effects, and executive function in youth. Our results may have important implications for understanding cognitive/ learning processes involved in nocebo effects.

Intelligence and Sensory Sensitivity as Predictors of Emotion Recognition Ability

The ability to recognize emotions from nonverbal cues (emotion recognition ability, ERA) is a core component of emotional intelligence, which has recently been conceptualized as a second-stratum factor of intelligence (MacCann et al., 2014). However, only few studies have empirically investigated the link between ERA, intelligence, and other mental abilities. The present study examined the associations between ERA, fluid intelligence, and sensory sensitivity in a sample of 214 participants. Results showed that both fluid intelligence and sensory sensitivity explained unique portions of variance in ERA. These findings suggest that future studies on ERA should include intelligence measures to assess the incremental validity of ERA above and beyond intelligence.

Genetic pleiotropy explains associations between musical auditory discrimination and intelligence

Musical aptitude is commonly measured using tasks that involve discrimination of different types of musical auditory stimuli. Performance on such different discrimination tasks correlates positively with each other and with intelligence. However, no study to date has explored these associations using a genetically informative sample to estimate underlying genetic and environmental influences. In the present study, a large sample of Swedish twins (N = 10,500) was used to investigate the genetic architecture of the associations between intelligence and performance on three musical auditory discrimination tasks (rhythm, melody and pitch). Phenotypic correlations between the tasks ranged between 0.23 and 0.42 (Pearson r values). Genetic modelling showed that the covariation between the variables could be explained by shared genetic influences. Neither shared, nor non-shared environment had a significant effect on the associations. Good fit was obtained with a two-factor model where one underlying shared genetic factor explained all the covariation between the musical discrimination tasks and IQ, and a second genetic factor explained variance exclusively shared among the discrimination tasks. The results suggest that positive correlations among musical aptitudes result from both genes with broad effects on cognition, and genes with potentially more specific influences on auditory functions.

Individual differences in motor timing and its relation to cognitive and fine motor skills

The present study investigated the relationship between individual differences in timing movements at the level of milliseconds and performance on selected cognitive and fine motor skills. For this purpose, young adult participants (N = 100) performed a repetitive movement task paced by an auditory metronome at different rates. Psychometric measures included the digit-span and symbol search subtasks from the Wechsler battery as well as the Raven SPM. Fine motor skills were assessed with the Purdue Pegboard test. Motor timing performance was significantly related (mean r = .3) to cognitive measures, and explained both unique and shared variance with information-processing speed of Raven's scores. No significant relations were found between motor timing measures and fine motor skills. These results show that individual differences in cognitive and motor timing performance is to some extent dependent upon shared processing not associated with individual differences in manual dexterity.

Acute effects of THC on time perception in frequent and infrequent cannabis users

RATIONALE

Cannabinoids have been shown to alter time perception, but existing literature has several limitations. Few studies have included both time estimation and production tasks, few control for subvocal counting, most had small sample sizes, some did not record subjects' cannabis use, many tested only one dose, and used either oral or inhaled administration of Δ⁹-tetrahydrocannabinol (THC), leading to variable pharmacokinetics, and some used whole-plant cannabis containing cannabinoids other than THC. Our study attempted to address these limitations.

OBJECTIVES

This study aims to characterize the acute effects of THC and frequent cannabis use on seconds-range time perception. THC was hypothesized to produce transient, dose-related time overestimation and underproduction. Frequent cannabis smokers were hypothesized to show blunted responses to these alterations.

METHODS

IV THC was administered at doses from 0.015 to 0.05 mg/kg to 44 subjects who participated in several double-blind, randomized, counterbalanced, crossover, placebo-controlled studies. Visual time estimation and production tasks in the seconds range were presented to subjects three times on each test day.

RESULTS

All doses induced time overestimation and underproduction. Chronic cannabis use had no effect on baseline time perception. While infrequent/nonsmokers showed temporal overestimation at medium and high doses and temporal underproduction at all doses, frequent cannabis users showed no differences. THC effects on time perception were not dose related.

CONCLUSIONS

A psychoactive dose of THC increases internal clock speed as indicated by time overestimation and underproduction. This effect is not dose related and is blunted in chronic cannabis smokers who did not otherwise have altered baseline time perception.

On sex-related differences in auditory and visual sensory functioning

The present study was designed to elucidate sex-related differences in two basic auditory and one basic visual aspect of sensory functioning, namely sensory discrimination of pitch, loudness, and brightness. Although these three aspects of sensory functioning are of vital importance in everyday life, little is known about whether men and women differ from each other in these sensory functions. Participants were 100 male and 100 female volunteers ranging in age from 18 to 30 years. Since sensory sensitivity may be positively related to individual levels of intelligence and musical experience, measures of psychometric intelligence and musical background were also obtained. Reliably better performance for men compared to women was found for pitch and loudness, but not for brightness discrimination. Furthermore, performance on loudness discrimination was positively related to psychometric intelligence, while pitch discrimination was positively related to both psychometric intelligence and levels of musical training. Additional regression analyses revealed that each of three predictor variables (sex, psychometric intelligence, and musical training) accounted for a statistically significant portion of unique variance in pitch discrimination. With regard to loudness discrimination, regression analysis yielded a statistically significant portion of unique variance for sex as a predictor variable, whereas psychometric intelligence just failed to reach statistical significance. The potential influence of sex hormones on sex-related differences in sensory functions is discussed.

Developing a Psychophysical Measure to Assess Duration Discrimination in the Millisecond Range

Duration discrimination in the range of milliseconds is essential for various aspects of behavior and individual differences. The present paper addresses important methodological issues, such as type of stimuli, type of task, method for threshold estimation, and temporal sensitivity of the psychophysical procedure, that should be borne in mind when developing a sensitive and reliable duration discrimination task. Furthermore, it introduces a psychophysical approach for the assessment of individual differences in duration discrimination of extremely brief intervals in the subsecond range. Monte Carlo simulations provide clear evidence that this task is sensitive enough to correctly detect a true difference between temporal stimuli as small as 2 ms with a high probability. Further, the distributional properties of individual performance scores obtained from 534 participants by means of the introduced duration discrimination task are presented.

Double dissociation of dopamine genes and timing in humans

A number of lines of evidence implicate dopamine in timing [Rammsayer, T. H. Neuropharmacological approaches to human timing. In S. Grondin (Ed.), Psychology of time (pp. 295-320). Bingley, UK: Emerald, 2008; Meck, W. H. Neuropharmacology of timing and time perception. Brain Research, Cognitive Brain Research, 3, 227-242, 1996]. Two human genetic polymorphisms are known to modulate dopaminergic activity. DRD2/ANKK1-Taq1a is a D(2) receptor polymorphism associated with decreased D(2) density in the striatum [Jönsson, E. G., Nothen, M. M., Grunhage, F., Farde, L., Nakashima, Y., Propping, P., et al. Polymorphisms in the dopamine D(2) receptor gene and their relationships to striatal dopamine receptor density of healthy volunteers. Molecular Psychiatry, 4, 290-296, 1999]; COMT Val158Met is a functional polymorphism associated with increased activity of the COMT enzyme such that catabolism of synaptic dopamine is greater in pFC [Meyer-Lindenberg, A., Kohn, P. D., Kolachana, B., Kippenhan, S., McInerney-Leo, A., Nussbaum, R., et al. Midbrain dopamine and prefrontal function in humans: Interaction and modulation by COMT genotype. Nature Neuroscience, 8, 594-596, 2005]. To investigate the role of dopamine in timing, we genotyped 65 individuals for DRD2/ANKK1-Taq1a, COMT Val158Met, and a third polymorphism, BDNF Val66Met, a functional polymorphism affecting the expression of brain-derived neurotrophic factor [Egan, M. F., Kojima, M., Callicott, J. H., Goldberg, T. E., Kolachana, B. S., Bertolino, A., et al. The BDNF val66met polymorphism affects activity-dependent secretion of BDNF and human memory and hippocampal function. Cell, 112, 257-269, 2003]. Subjects were tested on a temporal discrimination task with sub- and supra-second intervals (500- and 2000-msec standards) as well as a spontaneous motor tempo task. We found a double dissociation for temporal discrimination: the DRD2/ANKK1-Taq1a polymorphism (A1+ allele) was associated with significantly greater variability for the 500-msec duration only, whereas the COMT Val158Met polymorphism (Val/Val homozygotes) was associated with significantly greater variability for the 2000-msec duration only. No differences were detected for the BDNF Vall66Met variant. Additionally, the DRD2/ANKK1-Taq1a polymorphism was associated with a significantly slower preferred motor tempo. These data provide a potential biological basis for the distinctions between sub- and supra-second timing and suggest that BG are integral for the former whereas pFC is implicated in the latter.