Recently, there has been a renewed interest in avoidance behavior, and its applicability to clinical conditions such as anxiety, posttraumatic stress disorder (PTSD) and addiction. In a computer-based avoidance task for humans, participants control an on-screen spaceship, shoot at enemy targets (appetitive cue) to gain points, and learn to respond to an on-screen warning signal (WS) by entering safe “hiding” areas to escape/avoid an aversive event (point loss and on-screen explosion) paired with an on-screen aversive cue (bomb). Prior research on active avoidance in rodents suggests that avoidance learning is facilitated if the response also terminates the WS. Here, we adapted the computer-based task to investigate this idea in healthy humans. Two hundred and twenty-two young adults completed one of three conditions of the task: a non-contingent condition, where hiding caused omission/avoidance of the aversive event but did not terminate the WS; a fully-contingent condition, where hiding also caused omission/termination of all on-screen appetitive and aversive cues as well as terminating the WS; and a partially-contingent condition where hiding caused omission of the appetitive and aversive cues, but did not affect the WS. Both contingency manipulations decreased escape/avoidance behavior, as compared to the non-contingent condition where the WS and other cues are not affected by the avoidance behavior. This study has implications for the basic understanding of the mechanisms that affect avoidance behavior in humans.

Behavioral inhibition (BI) is a temperament characteristic which is associated with increased vulnerability to stress compared to non-behaviorally inhibited (NBI) counterparts. The physiologic and psychologic substrate which underlies the difference between BI and NBI individuals is unknown. Our previously published study demonstrated that BI individuals have decreased heart rate variability (HRV) relative to NBI individuals suggesting that BI individuals have less parasympathetic nervous system (PNS) output; however, it is unknown how BI affects perceived stress. Our current study tested the hypothesis that BI individuals would have higher perceived stress and physiologic stress during transdermal electrical stimulation (TES). Participants were administered TES beginning at 5mV and increased by 5mV increments until 100mV was reached. We used the Adult Measure of Behavioral Inhibition (AMBI) and the Perceived Stress Scale (PSS) to measure perceived stress, State-Trait Anxiety Inventory (STAI) scores to measure current stress, and a series of self-reported questionnaires to measure BI. Additionally, we used a BIOPAC data acquisition system to measure heart rate (HR), HRV, and blood pressure (BP) to measure physiological stress. Our pilot data suggests there was a non-significant trend of higher perceived stress after TES in BI individuals; however, there was a significant relationship between perceived stress and STAI scores. There was no significant difference in HR, HRV and BP between BI and NBI individuals. In conclusion, our pilot data suggests that a person’s BI or NBI status affects their perceived stress after a stressor is induced. BI individuals will have higher perceived stress after a stressor is presented as opposed to NBI individuals. We will conduct further studies using TES to further study this finding. Identification of these physiological factors could provide an additional mechanism for identifying individuals who are at a higher risk for developing stress and anxiety disorders. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

We assessed the cross-cultural role of Time Perspective (TP) tendencies [Past Positive (PP), Past Negative (PN), Present Hedonistic (PH), Present Fatalistic (PF), and Future (F)], the Deviation from a Balanced Time Perspective (DBTP) profile, the Deviation from a Negative Time Perspective (DNTP) profile, and mindfulness on life satisfaction (LS). The sample consisted of psychology undergraduate students (N = 867, M AGE = 20.19, SD = 3.417) in four countries: USA, Spain, Poland and Japan. We used a 17-item short version of the Zimbardo Time Perspective Inventory (ZTPI), the Mindful Attention Awareness Scale (MAAS), and the Satisfaction with Life Scale (SWLS) in all countries. For ensuring measurement invariance, we conducted pairwise CFAs for the ZTPI-17, MAAS and SWLS. Regression analyses showed that PN predicted decreased LS in Poland and Japan. PP predicted increased LS in Spain. F predicted increased LS in Poland. DNTP predicted decreased LS in Poland. Mindfulness predicted decreased LS in Japan and increased LS in USA, Spain and Poland. Moreover, mediation analyses revealed that the DBTP partially mediated the relationship between mindfulness and LS in Spain and USA. The DNTP partially mediated the relationship between mindfulness and LS in Spain, Poland and Japan (opposite direction). The findings suggest that the association of TP, mindfulness and LS differs across the investigated countries as a function of culture.

Behavioral inhibition (BI) is believed to be a genetically determined trait that affects roughly 33% of the human population. These individuals tend to respond to stressful situations differently than their non-behaviorally inhibited (NBI) counterparts. In the rodent population, a similar behavioral/stress model exists. The Sprague-Dawley (SD) strain often acts as a “control” among rat strains and can be considered to be the rat equivalent to NBI individuals, and the Wistar-Kyoto (WKY) strain is the rodent equivalent to BI individuals. The differences in the activation of the sympathetic nervous system between chronically stressed and non-stressed populations remain unknown. Our current study tested the hypothesis BI individuals and WKY rats will have increased stress responses. In humans, we tested physiological responses to increasing levels of carbon dioxide (CO2) through analyses of breathing, heart rate, and blood pressure. The Adult Measure of Behavioral Inhibition (AMBI) survey was used to determine the presence of BI. A 15-minute control period baseline was completed followed by an acquisition period of five minutes of each 3%, 5%, and 7% CO2, respectively. Preliminary results were analyzed through a CO2 sensitivity slope (inspired minute ventilation ((L/min) / end-tidal CO2) and show that BI individuals had increased, exaggerated responses to the respiratory stressors across the three levels of enhanced CO2. In the rodent model, signaled lever-press avoidance was used to examine the activation of stress responses. Rats were trained to avoid mild foot shock using a tone warning signal. As demonstrated previously, WKY rats acquired a higher level of avoidance responses. Rats were then food-deprived overnight and subsequently retested on signal lever-press avoidance. Food deprivation did not affect the high rate of avoidance seen in WKY rats; however, food deprivation increased the SD rate of avoidance to nearly the level of WKY rats. Our data suggest that WKY rats do not respond to food deprivation when paired with lever-press avoidance; however, SD rats do. Simply, the addition of a stressor causes SD rats to behave more similarly to their WKY counterparts. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Behavioral inhibition (BI) is a temperament characteristic that is associated with increased vulnerability to stress compared to their non-behaviorally inhibited (NBI) counterparts. Our previous study demonstrated that BI individuals have lower heart rate variability (HRV) than NBI individuals. This suggests that BI individuals have significantly less parasympathetic nervous system (PNS) output at rest. However, it is unknown how BI affects avoidance acquisition using a mildly stressful stimulus. Previous studies have shown that there are differences in the behavior found in Wistar-Kyoto rats, which exhibit BI behavior, compared to Sprague-Dawley control rats. Our current study will test the hypothesis that BI individuals learn to make escape and avoidance responses using subdermal ulnar nerve transdermal electrical stimulation (TES) more rapidly than NBI individuals, and also experience a greater increase in heart rate (HR) and blood pressure (BP). BI individuals were identified through a series of self-reported questionnaires. Three levels (30 mV, 50 mV, and 70 mV) of subdermal ulnar nerve TES were delivered to participants while receiving warning signals that predict the delivery of the TES. Participants had access to a button that when pressed during the light the warning signal prevented the delivery of the TES. This was scored as an avoidance response. If the button was pressed during the TES, it terminated the stimulation and was scored as an escape. HR and BP were also measured during TES using a BIOPAC data acquisition system. Our preliminary results do not suggest a difference between BI and NBI individual differences in HR or BP during TES (n=13); however, our future studies will investigate the differences in HRV and the acquisition of avoidance behavior during TES. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Behavioral inhibition (BI) is believed to be a genetically determined temperament characteristic that affects roughly 33% of the human population. These individuals are associated with a higher vulnerability to stressful stimuli compared to non-behaviorally inhibited (NBI) individuals. Our previous study demonstrated that BI individuals experienced decreased heart rate variability (HRV) compared to NBI individuals. Our study suggested that female BI individuals have significantly lower parasympathetic nervous system (PNS) activity, however, it is unknown how BI affects perceived stress. In order to better understand behavioral inhibition in humans, our laboratory explored salivary cortisol and amylase levels in response to stressful stimuli of breathing-enhanced CO2 (carbon dioxide). We hypothesized that BI individuals have a greater increase in both salivary cortisol and amylase after exposure to a stressful stimulus when compared to NBI individuals. Prior to the experiment, participants completed AMBI and RMBI forms. These forms indicate BI tendencies to participants, where AMBI is scored out of 32, where 15.5 is the threshold for BI tendencies, and RMBI is scored out of 36, 11.5 being the threshold. Salivary samples were taken at the beginning and end of the study. They were set up on a breathing apparatus and began to breathe room air for a 15 minute control period. Following this, participants either continued to breathe room air as the control group or were given 7% CO2, and then exposed to room air again. Overall, there was no difference in salivary cortisol and amylase between NBI and BI subjects following the onset of 7% CO2. Our data suggests that 7% CO2 may be too much of a respiratory stressor to reveal any physiological differences between the two groups. Ongoing studies will evaluate cortisol and amylase output after the CO2 dose response curve. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Behaviorally inhibited (BI) temperament is marked by heightened behavioral sensitivity to environmental threats. The degree to which threat sensitivity is reflected in cardiorespiratory responses has been relatively unexplored. Female college students were exposed to modest hypercapnia (7.0% CO2) or ambient air (AA) while engaging in a computerized task with cued reinforcement features. All physiological variables except for blood pressure were processed in 4 min epochs corresponding to pre-exposure, exposure, and post-exposure. Primary respiratory measures were respiratory frequency (fb), tidal volume (VT), and minute ventilation (VE). Electrocardiograms (ECGs) were processed using ARTiiFACT software with resultant heart rate variability (HRV) measures in the frequency domain and time domain. Consistent with the literature, modest hypercapnia increased VT, Fb, and VE. No differences in respiratory parameters were detected between BI and non-behaviorally inhibited individuals (NI). For HRV in the time domain, RMSSD and NN50 values increased during CO2 inhalation which then returned to pre-exposure levels after CO2 cessation. Hypercapnia increased high frequency (HF) power which then recovered. BI exhibited reduced low frequency (LF) power during the pre-exposure period. For NI, LF power reduced over the subsequent phases ameliorating differences between BI and NI. Hypercapnia improved the task performance of BI. This is the largest study of female reactivity to hypercapnia and associated HRV to date. In general, hypercapnia increased time domain HRV and HF power, suggesting a strong vagal influence. Those expressing BI exhibited similar respiratory and HRV reactivity to NI despite inherently reduced LF power. Although 7% CO2 represents a mild challenge to the respiratory and cardiovascular systems, it is nonetheless sufficient to explore inherent difference in stress reactivity in those vulnerable to develop anxiety disorders.

Individual differences or vulnerabilities must exist which bias some individuals toward psychopathology while others remain resilient in the face of trauma. Recent work has studied the effects of uncertainty on individuals expressing behavioral inhibition (BI). The current study extended this work with uncertainty to Wistar Kyoto (WKY) rats which are a behaviorally inhibited inbred strain that models learning vulnerabilities for anxiety disorders and posttraumatic stress disorder (PTSD). WKY rats exhibit superior avoidance performance in a signaled bar press avoidance task in which a tone conditioned stimulus (CS) signals a foot shock unconditional stimulus (US) when compared with non-inhibited Sprague-Dawley (SD) rats. In addition, WKY rats express enhanced eyeblink conditioning. Recent work with behaviorally inhibited humans has indicated that this enhanced eyeblink conditioning is more evident in conditions that insert CS- or US-alone trials into CS-US paired training, resulting in uncertain and suboptimal learning conditions. The current study examined the effects of partial predictability training, in which the CS signaled the US only one-half of the time, on the acquisition and expression of avoidance. Standard training with a fixed 60-s CS which predicted shock on 100% of trials was compared with training in which the CS predicted shock on 50% of trials (partial predictability) using a pseudorandom schedule. As expected, WKY rats acquired avoidance responses faster and to a greater degree than SD rats. Partial predictability of the US essentially reduced SD rats to escape responding. Partial predictability also reduced avoidance in WKY rats; however, adjusting avoidance rates for the number of potential pairings of the CS and US early in training suggested a similar degree of avoidance expression late in the last session of training. Enhanced active avoidance expression, even in uncertain learning conditions, can be interpreted as behaviorally inhibited WKY rats responding to the expectancy of the shock by avoiding, whereas non-inhibited SD rats were responding to the presence of the shock by escaping. Future work should explore how WKY and SD rats as well as behaviorally inhibited humans acquire and extinguish avoidance responses in uncertain learning situations.

Experiencing a trauma is necessary, but not sufficient, for the development of post-traumatic stress disorder (PTSD) in that most individuals who experience a trauma do not go on to develop PTSD. This suggests that identifiable vulnerabilities (i.e., diatheses) exist that increase the risk for the development of PTSD. One such factor is the personality temperament of behavioral inhibition (BI). Organisms that exhibit BI were studied in the context of avoidance learning and classical eyeblink conditioning. We present a body of evidence supporting a learning diathesis model in which behaviorally inhibited organisms exhibit enhanced acquisition and resistance to extinction in these tasks. Vulnerable individuals show learning-related enhancements when the learning situation involves some degree of uncertainty. We review the known brain circuitry involved in classical eyeblink conditioning in the context of the learning diathesis model. Finally, the data reviewed here demonstrate the value of studying vulnerability factors in humans and a rodent model using cerebellar-dependent learning tasks for understanding the acquisition and endurance of PTSD symptomatology.

Although many individuals who experience a trauma go on to develop post-traumatic stress disorder (PTSD), the rate of PTSD following trauma is only about 15-24%. There must be some pre-existing conditions that impart increased vulnerability to some individuals and not others. Diathesis models of PTSD theorize that pre-existing vulnerabilities interact with traumatic experiences to produce psychopathology. Recent work has indicated that personality factors such as behavioral inhibition (BI), harm avoidance (HA), and distressed (Type D) personality are vulnerability factors for the development of PTSD and anxiety disorders. These personality temperaments produce enhanced acquisition or maintenance of associations, especially avoidance, which is a criterion symptom of PTSD. In this review, we highlight the evidence for a relationship between these personality types and enhanced avoidance and associative learning, which may increase risk for the development of PTSD. First, we provide the evidence confirming a relationship among BI, HA, distressed (Type D) personality, and PTSD. Second, we present recent findings that BI is associated with enhanced avoidance learning in both humans and animal models. Third, we will review evidence that BI is also associated with enhanced eyeblink conditioning in both humans and animal models. Overall, data from both humans and animals suggest that these personality traits promote enhanced avoidance and associative learning, as well as slowing of extinction in some training protocols, which all support the learning diathesis model. These findings of enhanced learning in vulnerable individuals can be used to develop objective behavioral measures to pre-identify individuals who are more at risk for development of PTSD following traumatic events, allowing for early (possibly preventative) intervention, as well as suggesting possible therapies for PTSD targeted on remediating avoidance or associative learning. Future work should explore the neural substrates of enhanced avoidance and associative learning for behaviorally inhibited individuals in both the animal model and human participants.

Background/Objective: Coping styles play a role in how individuals respond to stress and therapy. One aspect of coping which has been linked to adverse outcomes including anxiety disorders and PTSD is avoidance. However, a tendency to avoid may affect the accuracy of paper and pencil inventories used to identify avoidant temperaments. Previously, we showed that a computer-based task in which an on-screen “avatar” is guided through a series of onscreen events could predict avoidance including behavioral inhibition, harm avoidance, and self-reported PTSD symptoms. Since some coping styles involve avoidance, we extended this work to determine whether scores on the avatar task would also differentiate avoidant and non-avoidant coping styles as measured by the Brief COPE.Methods: One hundred and fifty undergraduates voluntarily completed the avatar task and the Brief COPE.Results: Scores on the avatar task had a significant positive relationship with an aggregate score for the five avoidant coping styles and a significant negative relationship with an aggregate score for the nine non-avoidant coping styles.Conclusions: The effectiveness of the avatar task to differentiate coping styles based on avoidance further validates this task and also shows selectivity to avoidant coping styles as opposed to other non-avoidant coping styles.

Recent work has focused on a learning diathesis model in which specific personality factors such as behavioral inhibition (BI) may influence associative learning and in turn increase risk for the development of anxiety disorders. We have found in a series of studies that individuals self-reporting high levels of BI exhibit enhanced acquisition of conditioned eyeblinks. In the study reported here, hypotheses were extended to include distressed (Type D) personality which has been found to be related to BI. Type D personality is measured with the DS-14 scale which includes two subscales measuring negative affectivity (NA) and social inhibition (SI). We hypothesized that SI, which is similar to BI, would result in enhanced acquisition while the effect of NA is unclear. Eighty nine participants completed personality inventories including the Adult Measure of Behavioral Inhibition (AMBI) and DS-14. All participants received 60 acquisition trials with a 500 ms, 1000 Hz, tone CS and a co terminating 50 ms, 5 psi corneal airpuff US. Participants received either 100% CS-US paired trials or a schedule of partial reinforcement where 50% US alone trials were intermixed into CS-US training. Acquisition of CRs did not differ between the two training protocols. Whereas BI was significantly related to Type D, SI, and NA, only BI and SI individuals exhibited enhanced acquisition of conditioned eyeblinks as compared to non-inhibited individuals. Personality factors now including social inhibition can be used to identify individuals who express enhanced associative learning which lends further support to a learning diathesis model of anxiety disorders.

Several personality factors have been implicated in vulnerability to addiction by impacting learning and decision making. One such factor is intolerance of uncertainty (IU), the tendency to perceive uncertain situations negatively and avoid them. Conditioned place preference (CPP), which compares preference for contexts paired with reward, has been used to examine the motivation for both drug and non-drug rewards. However, preference for locations associated with non-drug reward, as well as the potential influence of IU, has not been thoroughly studied in individuals with addiction. In the current study, we examined CPP using a computer-based task in a sample of addicted individuals undergoing opioid maintenance treatment and never-addicted controls. Patients were confirmed to have higher IU than controls. In the CPP task, the two groups did not differ in overall time spent in the previously-rewarded context. However, controls were more likely than patients to immediately return to this context. Contrary to our predictions, IU was not a significant predictor of preference for the previously-rewarded context, although higher IU in controls was associated with a higher number of rewards obtained in the task. No such relationship was found in patients.

Intolerance of uncertainty (IU) is the tendency to interpret ambiguous situations as threatening and having negative consequences, resulting in feelings of distress and anxiety. IU has been linked to a number of anxiety disorders, and anxiety felt in the face of uncertainty may result in maladaptive behaviors such as impulsive decision making. Although there is strong evidence that anxiety and impulsivity are risk factors for addiction, there is a paucity of research examining the role of IU in this disorder. The rate of opioid addiction, in particular, has been rising steadily in recent years, which necessitates deeper understanding of risk factors in order to develop effective prevention and treatment methods. The current study tested for the first time whether opioid-dependent adults are less tolerant of uncertainty compared to a healthy comparison group. Opioid dependent patients undergoing methadone maintenance therapy (n = 114) and healthy comparisons (n = 69) completed the following scales: Intolerance of Uncertainty Scale, the Barrett Impulsivity Scale, and the State Trait Anxiety Inventory. Analysis revealed that these measures were positively correlated with each other and that opioid-dependent patients had significantly higher IU scores. Regression analysis revealed that anxiety mediated the relationship between IU and impulsivity. Hierarchical moderation regression found an interaction between addiction status and impulsivity on IU scores in that the relationship between these variables was only observed in the patient group. Findings suggest that IU is a feature of addiction but does not necessarily play a unique role. Further research is needed to explore the complex relationship between traits and how they may contribute to the development and maintenance of addiction.

Personality factors such as behavioral inhibition (BI), a temperamental tendency for avoidance in the face of unfamiliar situations, have been identified as risk factors for anxiety disorders. Personality factors are generally identified through self-report inventories. However, this tendency to avoid may affect the accuracy of these self-report inventories. Previously, a computer based task was developed in which the participant guides an on-screen "avatar" through a series of onscreen events; performance on the task could accurately predict participants' BI, measured by a standard paper and pencil questionnaire (Adult Measure of Behavioral Inhibition, or AMBI). Here, we sought to replicate this finding as well as compare performance on the avatar task to another measure related to BI, the harm avoidance (HA) scale of the Tridimensional Personality Questionnaire (TPQ). The TPQ includes HA scales as well as scales assessing reward dependence (RD), novelty seeking (NS) and persistence. One hundred and one undergraduates voluntarily completed the avatar task and the paper and pencil inventories in a counter-balanced order. Scores on the avatar task were strongly correlated with BI assessed via the AMBI questionnaire, which replicates prior findings. Females exhibited higher HA scores than males, but did not differ on scores on the avatar task. There was a strong positive relationship between scores on the avatar task and HA scores. One aspect of HA, fear of uncertainty was found to moderately mediate the relationship between AMBI scores and avatar scores. NS had a strong negative relationship with scores on the avatar task, but there was no significant relationship between RD and scores on the avatar task. These findings indicate the effectiveness of the avatar task as a behavioral alternative to self-report measures to assess avoidance. In addition, the use of computer based behavioral tasks are a viable alternative to paper and pencil self-report inventories, particularly when assessing anxiety and avoidance.

Studies of partial reinforcement in eyeblink conditioning have typically shown slower learning of a CS-US association when paired CS-US trials are interleaved with CS-alone trials. However, recent work has shown that CS-US learning is not slowed by interleaved US-alone trials. This discrepancy is surprising since both partial reinforcement protocols reduce the total number of paired CS-US trials. Previously, Kimble et al. (1955) reported that inserting a block of US-alone trials during CS-US training did not disrupt eyeblink acquisition. Here, we sought to replicate and extend these findings by comparing interleaved vs. blocked US-alone trials during CS-US paired training. Ninety-seven undergraduates volunteered for this experiment for research credit. Participants received 60 acquisition trials, consisting of either 100% CS-US paired trials, 50% US-alone trials intermixed with CS-US paired trials, or a block of 20 US-alone trials inserted between blocks of 20 CS-US trials. We also utilized a previously published computational model of hippocampal and cerebellar learning to test the effects of these US-alone protocols. Both empirical and computational results supported the finding that US-alone trials, either intermixed or inserted as a block of trials, do not disrupt acquisition of conditioned eyeblinks. Possible neural substrates of these US-alone effects are discussed.

Recent work has found that personality factors that confer vulnerability to addiction can also affect learning and economic decision making. One personality trait which has been implicated in vulnerability to addiction is intolerance to uncertainty (IU), i.e., a preference for familiar over unknown (possibly better) options. In animals, the motivation to obtain drugs is often assessed through conditioned place preference (CPP), which compares preference for contexts where drug reward was previously received. It is an open question whether participants with high IU also show heightened preference for previously rewarded contexts. To address this question, we developed a novel computer-based CPP task for humans in which participants guide an avatar through a paradigm in which one room contains frequent reward (i.e., rich) and one contains less frequent reward (i.e., poor). Following exposure to both contexts, subjects are assessed for preference to enter the previously rich and previously poor room. Individuals with low IU showed little bias to enter the previously rich room first, and instead entered both rooms at about the same rate which may indicate a foraging behavior. By contrast, those with high IU showed a strong bias to enter the previously rich room first. This suggests an increased tendency to chase reward in the intolerant group, consistent with previously observed behavior in opioid-addicted individuals. Thus, the personality factor of high IU may produce a pre-existing cognitive bias that provides a mechanism to promote decision-making processes that increase vulnerability to addiction.

Recent work has found that behaviorally inhibited (BI) individuals exhibit enhanced eyeblink conditioning in omission and yoked training as well as with schedules of partial reinforcement. We hypothesized that spacing CS-US paired trials over a longer period of time by extending and varying the inter-trial interval (ITI) would facilitate learning. All participants completed the Adult Measure of Behavioural Inhibition (AMBI) and were grouped as behaviorally inhibited (BI) and non-behaviorally inhibited (NI) based on a median split score of 15.5. All participants received 3 US alone trials and 30CS-US paired trials for acquisition training and 20CS alone trials for extinction training in one session. Conditioning stimuli were a 500 ms tone conditioned stimulus (CS) and a 50-ms air puff unconditional stimulus (US). Participants were randomly assigned to receive a short ITI (mean = 30 + / - 5 s), a long ITI (mean = 57 + / - 5 s) or a variable long ITI (mean = 57 s, range 25-123 s). No significant ITI effects were observed for acquisition or extinction. Overall, anxiety vulnerable individuals exhibited enhanced conditioned eyeblink responses as compared to non-vulnerable individuals. This enhanced acquisition of CRs was significant in spaced training with a variable long ITI, but not the short or long ITI. There were no significant effects of ITI or BI on extinction. These findings are interpreted based on the idea that uncertainty plays a role in anxiety and can enhance associative learning in anxiety vulnerable individuals. (C) 2016 Elsevier B.V. All rights reserved.

Reviewed by: Old Man River: The Mississippi River in North American History by Paul Schneider Michael Allen Paul Schneider, Old Man River: The Mississippi River in North American History. New York: Henry Holt, 2013. 416 pp. $20.00. The title of this book recalls a bygone era in more ways than one. Beginning nearly two centuries ago, a strongly held belief that the Mississippi River Valley was vitally important to American history and culture led scholars to write about it. Beginning with Timothy Flint’s Condensed Geography and History . . . of the Mississippi Valley (1828), authors described the Mississippi Valley as an exceptional cultural region. Their works include John W. Monette’s History of the Discovery and Settlement of the Valley of the Mississippi (1848); Henry Lewis’s The Valley of the Mississippi (1854; originally published in German); J. W. Foster’s The Mississippi Valley: Its Physical Geography . . . (1869); and C. B. Walker’s vital The Mississippi Valley, and Prehistoric Events . . . (1880). Mark Twain’s Life on the Mississippi (1881) was followed by Theodore Roosevelt’s The Winning of the West (1889–96), a paean to the Great Valley, and James K. Hosmer’s concise chronological overview, A Short History of the Mississippi Valley (1901). Next, Frederick Jackson Turner outlined “The Significance of the Mississippi Valley in American History” in a 1908 keynote speech before the Mississippi Valley Historical Association, an organization whose very name and existence reflects the degree to which Americans saw the Great Valley as the heart of America. Throughout the twentieth century, Roosevelt’s and Turner’s sweeping portraits begat a number of more focused books about selected aspects of the Mississippi River Valley. Beginning in the 1970s, after the name-change of the Mississippi Valley Historical Association to the Organization of American Historians, new social historians produced scores of works focused on race, class, gender, and environment in the Valley of the Mississippi. Surveying all of this literature, one is struck by the fact that, of the hundreds of books written about the Mississippi Valley, all but a dozen [End Page 140] avoid synthesis. And of those dozen books which take a sweeping view, nearly all were written in the middle and late nineteenth century. Paul Schneider brings an impressive resume to Old Man River: The Mississippi River in North American History. A native of Amherst, Massachusetts, and graduate of Brown University, he has published in the New Yorker, Esquire, and the New York Times. He is author of the well-received The Adirondacks: A History of America’s First Wilderness (1997), followed by a popular history of Cape Cod and Martha’s Vineyard and several other books. He is currently editor of Martha’s Vineyard Magazine. “It’s impossible to imagine America without the Mississippi,” Paul Schneider states. “The river’s history is our history” (1). He begins his history of the Mississippi during the ice age and tells the story of prehistoric animals and men in the Great Valley. He devotes a major section to Mississippian Moundbuilders and their American Indian descendants, and then launches a discussion about the major European explorers—De Soto, La Salle, and Marquette—and the eighteenth century arrival of the British and their American subjects. This takes him into the history of the early American republic, Lewis and Clark, and the keelboat, flatboat, and steamboat ages on western rivers. The role of the Mississippi in General U.S. Grant’s Civil War campaigns marks the book’s crescendo, while a concluding section focuses on the author’s own Mississippi travels and his concerns for the river’s natural environment in an industrial age. Old Man River’s ample bibliography is composed of a mix of old and new scholarly secondary sources, firsthand accounts, and newspaper and magazine articles. As in his other publications, Schneider is adept at working with dozens of sources and expeditiously serving up documented, engaging, book-length narrative prose. This is not so much a book about the Mississippi Valley as one about events on or near the river itself. Schneider seems unaware of all but a few of the authors mentioned in the first paragraph of this review, or of his place in carrying on...

Anxiety vulnerable individuals exhibit enhanced acquisition of conditioned eyeblinks as well as enhanced proactive interference from conditioned stimulus (CS) or unconditioned stimulus (US) alone pre-exposures (Holloway et al., 2012). US alone pre-exposures disrupt subsequent conditioned response (CR) acquisition to CS-US paired trials as compared to context pre-exposure controls. While Holloway et al. (2012) reported enhanced acquisition in high trait anxiety individuals in the context condition, anxiety vulnerability effects were not reported for the US alone pre-exposure group. It appears from the published data that there were no differences between high and low anxiety individuals in the US alone condition. In the work reported here, we sought to extend the findings of enhanced proactive interference with US alone pre-exposures to determine if the enhanced conditioning was disrupted by proactive interference procedures. We also were interested in the spontaneous eyeblinks during the pre-exposure phase of training. We categorized individuals as anxiety vulnerability or non-vulnerable individuals based scores on the Adult Measure of Behavioral Inhibition (AMBI). Sixty-six participants received 60 trials consisting of 30 US alone or context alone pre-exposures followed by 30 CS-US trials. US alone pre-exposures not only disrupted CR acquisition overall, but behaviorally inhibited (BI) individuals exhibited enhanced proactive interference as compared to non-inhibited (NI) individuals. In addition, US alone pre-exposures disrupted the enhanced acquisition observed in BI individuals as compared to NI individuals following context alone pre-exposures. Differences were also found in rates of spontaneous eyeblinks between BI and NI individuals during context pre-exposure. Our findings will be discussed in the light of the neural substrates of eyeblink conditioning as well as possible factors such as hypervigilance in the amygdala and hippocampal systems, and possible learned helplessness. Applications of these findings of enhanced proactive interference in BI individuals to pre-exposure therapies to reduce anxiety disorders such as posttraumatic stress disorder (PTSD) will be discussed.