Effects of priming goal pursuit on implicit sequence learning.

Implicit learning, the type of learning that occurs without intent to learn or awareness of what has been learned, has been thought to be insensitive to the effects of priming, but recent studies suggest this is not the case. One study found that learning in the serial reaction time (SRT) task was improved by nonconscious goal pursuit, primed via a word search task (Eitam et al. in Psychol Sci 19:261-267, 2008). In two studies, we used the goal priming word search task from Eitam et al., but with a different version of the SRT, the alternating serial reaction time task (ASRT). Unlike the SRT, which often results in explicit knowledge and assesses sequence learning at one point in time, the ASRT has been shown to be implicit through sensitive measures of judgment, and it enables sequence learning to be measured continuously. In both studies, we found that implicit learning was superior in the groups that were primed for goal achievement compared to control groups, but the effect was transient. We discuss possible reasons for the observed time course of the positive effects of goal priming, as well as some future areas of investigation to better understand the mechanisms that underlie this effect, which could lead to methods to prolong the positive effects.

Not just scenery: viewing nature pictures improves executive attention in older adults.

UNLABELLED: BACKGROUND/STUDY CONTEXT: Attention Restoration Theory (Kaplan, 1995, Journal of Environmental Psychology, 15, 169-182) suggests that exposure to nature improves attention. Berman, Jonides, and Kaplan (2008, Psychological Science, 19, 1207-1212) showed that simply viewing nature pictures improves executive attention in young adults. The present study is the first to investigate this Nature Effect in older adults. The authors investigated whether executive attention could be improved in healthy older adults following brief exposure to nature pictures. METHODS: Thirty healthy older adults (64-79 years old) and 26 young university students (18-25 years old) participated. They completed the Attention Network Test before and after 6 min of viewing either nature or urban pictures, with random assignment into a picture type. Attention immediately before (most fatigued) and after (most restored) picture viewing was measured, and change in attention was compared between age groups and picture types. RESULTS: Results showed that viewing nature, but not urban, pictures significantly improved executive attention in both older and young adults as measured by the Attention Network Test, with similar effects seen in the two age groups. Alerting and orienting attention scores were not affected by picture viewing. CONCLUSION: This was the first study to show that viewing nature pictures improves attention in older adults, and to show that it is executive attention, specifically, that is improved. Among a growing number of interventions, nature exposure offers a quick, inexpensive, and enjoyable means to provide a temporary boost in executive attention.

A novel psychophysical method for estimating the time course of olfactory rapid adaptation in humans.

In this presentation, we describe a novel method for estimating the onset time course of psychophysical odor adaptation in human observers. The method employs stimulus conditions derived from an analogous stimulus paradigm in audition. To test this procedure, we used liquid-dilution olfactometry to estimate 2-bottle discrimination thresholds for brief (600 ms) presentations of vanilla odor; 17 volunteers (14 females; ages 18-24) served as participants. The adapting odorant concentration for each participant was set relative to baseline threshold for the 600-ms target alone (i.e., the same level relative to each participant's threshold). To characterize the adaptation-onset time course, we compared thresholds for targets presented simultaneously with the adapting stimulus as a function of the relative delay between the onset of the adapting stimulus and onset of the target. As predicted from the analogous auditory studies, thresholds for the target stimulus increased in an orderly manner with increases in adaptation-to-target onset delay (i.e., as the adaptation process progressively decreased sensitivity). Initial increases in threshold were consistently observed for the briefest onset delays of 50-100 ms. An onset time constant was estimated at 319 ms by fitting a 2-component exponential to the mean group function. Adaptation magnitude was dependent on the level of adapting odorant, relative to threshold. When thresholds were measured in one participant with a different, unrelated target odorant, cineole, there was no effect of the vanilla-adapting stimulus on threshold. The results suggest that olfactory rapid adaptation is measurable psychophysically within 50-200 ms after odor onset, values consistent with physiological measures of adaptation in olfactory receptor neurons. This novel stimulus paradigm offers a powerful psychophysical tool to study both odor adaptation and stimulus interactions at the olfactory periphery.

Discrimination of "odorless" mineral oils alone and as diluents by behaviorally trained mice.

Odorant diluents are generally chosen because of their odorless qualities, allowing them to dilute a target odorant without otherwise altering its perception. Unpublished observations from our laboratory, however, suggest that mineral oil (MO), a common diluent for oil-based odorants, may possess a distinct odor when used in the behavioral testing of mice. To test this, mice were trained to discriminate between 4 brands of MO, using a commercial, liquid-dilution olfactometer and a 2-odorant discrimination task. The results demonstrate that mice were able to detect MOs and to discriminate between MO pairs obtained from different sources. Additionally, we sought to determine if mice could discriminate different MOs when used as a diluent for suprathreshold levels of cineole. Mice were required to discriminate between bottles containing identical concentrations of cineole diluted in different brands of MO. The results showed that the mice readily discriminated each cineole/MO pairing. These data demonstrate that mice are able to detect and discriminate MOs obtained from different sources, both when presented alone and in mixtures. The results also indicate that MO is not an odorless diluent and should be used with caution in olfactory experiments, as the perception of odors being diluted may be unintentionally altered.

Linking Emotional Reactivity Between Laboratory Tasks and Immersive Environments Using Behavior and Physiology.

An event or experience can induce different emotional responses between individuals, including strong variability based on task parameters or environmental context. Physiological correlates of emotional reactivity, as well as related constructs of stress and anxiety, have been found across many physiological metrics, including heart rate and brain activity. However, the interdependances and interactions across contexts and between physiological systems are not well understood. Here, we recruited military and law enforcement to complete two experimental sessions across two different days. In the laboratory session, participants viewed high-arousal negative images while brain activity electroencephalogram (EEG) was recorded from the scalp, and functional connectivity was computed during the task and used as a predictor of emotional response during the other experimental session. In an immersive simulation session, participants performed a shoot-don't-shoot scenario while heart rate electrocardiography (ECG) was recorded. Our analysis examined the relationship between the sessions, including behavioral responses (emotional intensity ratings, task performance, and self-report anxiety) and physiology from different modalities [brain connectivity and heart rate variability (HRV)]. Results replicated previous research and found that behavioral performance was modulated within-session based on varying levels of emotional intensity in the laboratory session (t (24) = 4.062, p < 0.0005) and stress level in the simulation session (Z = 2.45, corrected p-value = 0.0142). Both behavior and physiology demonstrated cross-session relationships. Behaviorally, higher intensity ratings in the laboratory was related to higher self-report anxiety in the immersive simulation during low-stress (r = 0.465, N = 25, p = 0.019) and high-stress (r = 0.400, N = 25, p = 0.047) conditions. Physiologically, brain connectivity in the theta band during the laboratory session significantly predicted low-frequency HRV in the simulation session (p < 0.05); furthermore, a frontoparietal connection accounted for emotional intensity ratings during the attend laboratory condition (r = 0.486, p = 0.011) and self-report anxiety after the high-stress simulation condition (r = 0.389, p = 0.035). Interestingly, the predictive power of the brain activity occurred only for the conditions where participants had higher levels of emotional reactivity, stress, or anxiety. Taken together, our findings describe an integrated behavioral and physiological characterization of emotional reactivity.

Intra-Individual Variability in Vagal Control Is Associated With Response Inhibition Under Stress.

Dynamic intra-individual variability (IIV) in cardiac vagal control across multiple situations is believed to contribute to adaptive cognition under stress; however, a dearth of research has empirically tested this notion. To this end, we examined 25 U.S. Army Soldiers (all male, mean age = 30.73, standard deviation (SD) = 7.71) whose high-frequency heart rate variability (HF-HRV) was measured during a resting baseline and during three conditions of a shooting task (training, low stress, high stress). Response inhibition was measured as the correct rejection (CR) of friendly targets during the low and high stress conditions. We tested the association between the SD of HF-HRV across all four task conditions (IIV in vagal control) and changes in response inhibition between low and high stress. Greater differences in vagal control between conditions (larger IIV) were associated with higher tonic vagal control during rest, and stronger stress-related decreases in response inhibition. These results suggest that flexibility in vagal control is supported by tonic vagal control, but this flexibility also uniquely relates to adaptive cognition under stress. Findings are consistent with neurobehavioral and dynamical systems theories of vagal function.

Different profiles of decision making and physiology under varying levels of stress in trained military personnel.

Decision making is one of the most vital processes we use every day, ranging from mundane decisions about what to eat to life-threatening choices such as how to avoid a car collision. Thus, the context in which our decisions are made is critical, and our physiology enables adaptive responses that account for how environmental stress influences our performance. The relationship between stress and decision making can additionally be affected by one's expertise in making decisions in high-threat environments, where experts can develop an adaptive response that mitigates the negative impacts of stress. In the present study, 26 male military personnel made friend/foe discriminations in an environment where we manipulated the level of stress. In the high-stress condition, participants received a shock when they incorrectly shot a friend or missed shooting a foe; in the low-stress condition, participants received a vibration for an incorrect decision. We characterized performance using signal detection theory to investigate whether a participant changed their decision criterion to avoid making an error. Results showed that under high-stress, participants made more false alarms, mistaking friends as foes, and this co-occurred with increased high frequency heart rate variability. Finally, we examined the relationship between decision making and physiology, and found that participants exhibited adaptive behavioral and physiological profiles under different stress levels. We interpret this adaptive profile as a marker of an expert's ingrained training that does not require top down control, suggesting a way that expert training in high-stress environments helps to buffer negative impacts of stress on performance.

Does a simultaneous memory load affect older and younger adults' implicit associative learning?

This study investigated the effects of a simultaneous memory load on implicit associative sequence learning using the Triplets Learning Task (TLT). Participants in the Simultaneous condition held a secondary task memory load during the TLT, while those in the Sequential condition also performed both tasks, but successively, rather than simultaneously. Thus, the Simultaneous condition had a memory load during the TLT, while the Sequential condition did not. Probe blocks without the secondary task allowed separation of effects on learning from effects on its expression. Results revealed that the simultaneous memory load affected older, but not younger adults, by suppressing the expression of learning, not learning itself. Thus, older and younger adults can learn probabilistic associations while holding a simultaneous memory load, but the load can limit the extent to which older adults adapt their performance to environmental structure. Results are consistent with theories which propose that implicit associative learning does not call on limited capacity resources, and highlight the importance of distinguishing effects of dual tasks on the expression of learning from those on learning itself.

Implicit sequence learning in people with Parkinson's disease.

Implicit sequence learning involves learning about dependencies in sequences of events without intent to learn or awareness of what has been learned. Sequence learning is related to striatal dopamine levels, striatal activation, and integrity of white matter connections. People with Parkinson's disease (PD) have degeneration of dopamine-producing neurons, leading to dopamine deficiency and therefore striatal deficits, and they have difficulties with sequencing, including complex language comprehension and postural stability. Most research on implicit sequence learning in PD has used motor-based tasks. However, because PD presents with motor deficits, it is difficult to assess whether learning itself is impaired in these tasks. The present study used an implicit sequence learning task with a reduced motor component, the Triplets Learning Task (TLT). People with PD and age- and education-matched healthy older adults completed three sessions (each consisting of 10 blocks of 50 trials) of the TLT. Results revealed that the PD group was able to learn the sequence, however, when learning was examined using a Half Blocks analysis (Nemeth et al., 2013), which compared learning in the 1st 25/50 trials of all blocks to that in the 2nd 25/50 trials, the PD group showed significantly less learning than Controls in the 2nd Half Blocks, but not in the 1st. Nemeth et al. (2013) hypothesized that the 1st Half Blocks involve recall and reactivation of the sequence learned, thus reflecting hippocampal-dependent learning, while the 2nd Half Blocks involve proceduralized behavior of learned sequences, reflecting striatal-based learning. The present results suggest that the PD group had intact hippocampal-dependent implicit sequence learning, but impaired striatal-dependent learning. Thus, sequencing deficits in PD are likely due to striatal impairments, but other brain systems, such as the hippocampus, may be able to partially compensate for striatal decline to improve performance.