Instructed extinction in human fear conditioning: History, recent developments, and future directions

Instructed extinction is an experimental manipulation that involves informing participants after the acquisition of fear learning that the unconditional stimulus (US) will no longer be presented. It has been used as a laboratory analogue to assess the capacity of cognitive interventions to reduce experimentally induced fear. In this review, we examine and integrate research on instructed extinction and discuss its implications for clinical practice. Overall, the results suggest that instructed extinction reduces conditional fear responding and facilitates extinction learning, except when conditional stimulus valence is assessed as an index of fear or when fear is conditioned to images of animal fear-relevant stimuli (snakes and spiders) or with a very intense US. These exceptions highlight potential boundary conditions for the reliance on cognitive interventions when treating fear in clinical settings

Startle modulation and explicit valence evaluations dissociate during backward fear conditioning

Blink startle magnitude is linearly modulated by affect such that, relative to neutral stimuli, startle magnitude is inhibited during pleasant stimuli and potentiated during unpleasant stimuli. Andreatta, Mühlberger, Yarali, Gerber, and Pauli (2010), however, report a dissociation between startle modulation and explicit valence evaluations during backward conditioning, a procedure in which the unconditional stimulus precedes the conditional stimulus (CS). Relative to controls, startles elicited during the CS were inhibited, suggesting that the CS had acquired positive valence, but participants still evaluated the CS as unpleasant after the experiment. In Experiment 1, we aimed to replicate this dissociation using a trial-by-trial measure of CS valence to measure startle modulation and CS valence simultaneously during forward and backward differential fear conditioning. In Experiment 2, we examined whether early and late portions of the CS could acquire differential valence by presenting startle probes at early and late probe positions during the CS. In both experiments, the dissociation between startle modulation and explicit valence evaluations in backward conditioning replicated, with CS+ evaluated as less pleasant than CS-, but startles elicited during CS+ inhibited relative to CS-. In Experiment 2, we provide preliminary evidence that this inhibition was present early, but not late, during the CS+. The results replicate the dissociation between implicit and explicit CS valence reported by Andreatta et al. (2010) using a trial-by-trial measure of valence. We also provide preliminary evidence that this dissociation may occur because the implicit and explicit measures are recorded at different times during the CS presentation

When orienting and anticipation dissociate - a case for scoring electrodermal responses in multiple latency windows in studies of human fear conditioning

Electrodermal activity in studies of human fear conditioning is often scored by distinguishing two electrodermal responses occurring during the conditional stimulus–unconditional stimulus interval. These responses, known as first interval responding (FIR) and second interval responding (SIR), are reported to be differentially sensitive to the effects of orienting and anticipation. Recently, the FIR/SIR scoring convention has been questioned, with some arguing in favor of scoring a single response within the entire conditional stimulus–unconditional stimulus interval (entire interval responding, EIR). EIR can be advantageous in practical terms but may fail to capture experimental effects when manipulations produce dissociations between orienting and anticipation. As an illustration, we rescored the data reported by Luck and Lipp (2015b) using both FIR/SIR and EIR scoring techniques and provide evidence that the EIR scoring technique fails to detect the effects of instructed extinction, an experimental manipulation which produces a dissociation between orienting and anticipation. Thus, using a technique that scores electrodermal response indices of fear conditioning in multiple latency windows is recommended

The influence of contingency reversal instructions on electrodermal responding and conditional stimulus valence evaluations during differential fear conditioning

In differential fear conditioning, the instruction that the conditional stimulus (CS) will no longer be followed by the unconditional stimulus (US; instructed extinction) reduces differential physiological responding (expectancy learning) but leaves differential CS valence evaluations (evaluative learning) intact. This dissociation suggests that expectancy, but not evaluative learning, responds to contingency instructions. Alternatively, as instructed extinction removes the threat of receiving the US, this dissociation could be caused by a drop in participants' arousal levels which could render the physiological indices of fear learning less sensitive. To test this alternative explanation, we examined the impact of an instructed reversal manipulation on electrodermal responding and CS valence evaluations. After instructed reversal, electrodermal responses to CS+ decreased and electrodermal responses to CS- increased, in the instruction, but not in the control group. In addition, there was some evidence for an instruction dependent change in CS valence, however, this finding seems limited to changes in CS+ valence and possible explanations for this finding are discussed. Overall, the study confirms that the dissociation detected in instructed extinction studies is unlikely to be caused by a drop in the participants' arousal levels

Extraction of information about periodic orbits from scattering functions

As a contribution to the inverse scattering problem for classical chaotic systems, we show that one can select sequences of intervals of continuity, each of which yields the information about period, eigenvalue and symmetry of one unstable periodic orbit.Comment: LaTeX, 13 pages (includes 5 eps-figures

Block Crossings in Storyline Visualizations

Storyline visualizations help visualize encounters of the characters in a story over time. Each character is represented by an x-monotone curve that goes from left to right. A meeting is represented by having the characters that participate in the meeting run close together for some time. In order to keep the visual complexity low, rather than just minimizing pairwise crossings of curves, we propose to count block crossings, that is, pairs of intersecting bundles of lines. Our main results are as follows. We show that minimizing the number of block crossings is NP-hard, and we develop, for meetings of bounded size, a constant-factor approximation. We also present two fixed-parameter algorithms and, for meetings of size 2, a greedy heuristic that we evaluate experimentally.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

Two Hands on the Wheel: Steering Robotics Innovation in Useful Directions

Practices of innovation are not autonomous. Research in STS and innovation studies has shown both the speed of knowledge production, and crucially its direction, may be susceptible to change. Indeed, interventions to the rate and direction of innovation are crucial if we are to address address the transformations needed in the economy and wider society that might for example avoid the extremes of climate change and meet the sustainable development goals. Yet interventions in these regards remain inexact. Innovation policy is one way in which government seeks to drive the production of policy towards or away from specific ends. Recent initiatives such as efforts to include "co-creation" have sought to open up innovation practices to a wider range of actors, broadening participation. But what arrangements of objects, sites, publics, and concepts do these instruments create? And how might these arrangements contribute to the laudable if lofty goals of steering innovation in useful directions? The paper follows two innovation instruments designed to influence innovation in the domain of robotics; the establishment of a "certified testbed" and a "co-creation facility". The paper asks how do co-creation instruments in the field of robotics steer innovation towards social progress or otherwise? Using a situated analysis method, this paper traces the two instruments in and around a single robotics innovation facility in the United Kingdom

Verbal instructions targeting valence alter negative conditional stimulus evaluations (but do not affect reinstatement rates)

Negative conditional stimulus (CS) valence acquired during fear conditioning may enhance fear relapse and is difficult to remove as it extinguishes slowly and does not respond to the instruction that unconditional stimulus (US) presentations will cease. We examined whether instructions targeting CS valence would be more effective. In Experiment 1, an image of one person (CS+) was paired with an aversive US, while another (CS-) was presented alone. After acquisition, participants were given positive information about the CS+ poser and negative information about the CS- poser. Instructions reversed the pattern of differential CS valence present during acquisition and eliminated differential electrodermal responding. In Experiment 2, we compared positive and negative CS revaluation by providing positive/negative information about the CS+ and neutral information about CS-. After positive revaluation, differential valence was removed and differential electrodermal responding remained intact. After negative revaluation, differential valence was strengthened and differential electrodermal responding was eliminated. Unexpectedly, the instructions did not affect the reinstatement of differential electrodermal responding

Structure factors of harmonic and anharmonic Fibonacci chains by molecular dynamics simulations

The dynamics of quasicrystals is characterized by the existence of phason excitations in addition to the usual phonon modes. In order to investigate their interplay on an elementary level we resort to various one-dimensional model systems. The main observables are the static, the incoherent, and the coherent structure factor, which are extracted from molecular dynamics simulations. For the validation of the algorithms, results for the harmonic periodic chain are presented. We then study the Fibonacci chain with harmonic and anharmonic interaction potentials. In the dynamic Fibonacci chain neighboring atoms interact by double-well potentials allowing for phason flips. The difference between the structure factors of the dynamic and the harmonic Fibonacci chain lies in the temperature dependence of the phonon line width. If a bias is introduced in the well depth, dispersionless optic phonon bands split off.Comment: 12 pages, 15 figure