A comparison of open and closed loop applications of the minimum distance guidance technique

A comparison is made of open and closed loop applications of a second order guidance algorithm, using the minimum distance strategy. A nonlinear reoptimization procedure is used as the ideal guidance history. The system model used for the comparison is a low-thrust vehicle performing a minimum time, three-dimensional, heliocentric Earth-Mars transfer. For the example problem considered, closed loop guidance proves to be much more accurate on satisfaction of the final state than the open loop procedure. On the other hand, closed loop guidance proves to be much more vulnerable to perturbation by highly nonlinear regions in the trajectory. Finally, the results indicate that for this problem the best loop closure interval is at each integration step, about one day, or more often, if possible

Attention with a mindful attitude attenuates subjective appetitive reactions and food intake following food-cue exposure.

BACKGROUND: Excessive energy intake that contributes to overweight and obesity is arguably driven by pleasure associated with the rewarding properties of energy-dense palatable foods. It is important to address influences of external food cues in food-abundant societies where people make over 200 food related decisions each day. This study experimentally examines protective effects of a mindful attention induction on appetitive measures, state craving and food intake following exposure to energy-dense foods. METHOD: Forty females were randomly allocated to a standard food-cue exposure condition in which attention is brought to the hedonic properties of food or food-cue exposure following a mindful attention induction. Appetitive reactions were measured pre, post and ten minutes after post-cue exposure, after which a plate of cookies was used as a surreptitious means of measuring food intake. RESULTS: Self-reported hunger remained unchanged and fullness significantly increased for the mindful attention group post-cue exposure whereas hunger significantly increased for the standard attention group and fullness remained unchanged. There was no significant between-group difference in state craving post-cue exposure and ten minutes later. Significantly more cookies were eaten by the standard attention group ten minutes post-cue exposure although no significant between-group differences in appetitive and craving measures were reported at that time. CONCLUSION: Our results point to a promising brief intervention strategy and highlights the importance of distinguishing mindful attention from attention. Results also demonstrate that mindful attention can influence food intake even when craving and hunger are experienced

On the Computability of Solomonoff Induction and Knowledge-Seeking

Solomonoff induction is held as a gold standard for learning, but it is known to be incomputable. We quantify its incomputability by placing various flavors of Solomonoff's prior M in the arithmetical hierarchy. We also derive computability bounds for knowledge-seeking agents, and give a limit-computable weakly asymptotically optimal reinforcement learning agent.Comment: ALT 201

Extreme State Aggregation Beyond MDPs

We consider a Reinforcement Learning setup where an agent interacts with an environment in observation-reward-action cycles without any (esp.\ MDP) assumptions on the environment. State aggregation and more generally feature reinforcement learning is concerned with mapping histories/raw-states to reduced/aggregated states. The idea behind both is that the resulting reduced process (approximately) forms a small stationary finite-state MDP, which can then be efficiently solved or learnt. We considerably generalize existing aggregation results by showing that even if the reduced process is not an MDP, the (q-)value functions and (optimal) policies of an associated MDP with same state-space size solve the original problem, as long as the solution can approximately be represented as a function of the reduced states. This implies an upper bound on the required state space size that holds uniformly for all RL problems. It may also explain why RL algorithms designed for MDPs sometimes perform well beyond MDPs.Comment: 28 LaTeX pages. 8 Theorem

Mindfulness based emotional eating awareness training: taking the emotional out of eating.

Purpose: Emotional eating is important to study and address because it predicts poor outcome in weight loss interventions. Interventions have only touched the surface in terms of addressing emotional eating. Mindfulness approaches can address emotional eating by modification of emotion regulation and appetitive traits. The current study involved development of an emotional eating specific mindfulness intervention and assessment of its effect on appetitive traits associated with emotional eating. Methods: Participants (n = 14; Age M = 29yr; 90% female) completed baseline and end-of intervention self-report measures of emotional eating, food-cue reactivity, mindfulness, intuitive eating, emotional impulse regulation, stress, and a behavioural measure of inhibitory control. During the 6- week intervention, mindfulness meditation skills were taught weekly embedded in a psychoeducational curriculum about emotional eating. Results: Paired t-tests, controlled for type 1 error, revealed significant improvements in food-cue reactivity, intuitive eating, emotional impulse regulation, inhibitory control and stress (ps < .05; d: .58 to 1.54). Changes in emotional eating approached significance (p = .075, d = .66). Conclusion: The intervention purposefully did not focus on weight loss and recruited participants who had self-declared difficulties with emotional eating. The positive outcomes suggest that intervening with mindfulness training before weight loss is attempted has the potential to change psychological factors that underpin overeating and undermine weight loss efforts. The study provides proof of principle as a basis to design a randomized control trial to assess rigorously the effectiveness the intervention as a precursor to a weight loss intervention. Level of Evidence: Level IV, uncontrolled trial

Dietary restraint moderates the effects of food exposure on women's body and weight satisfaction

The influence of dietary restraint and food exposure on body satisfaction was tested. Body and weight satisfaction were measured before and after exposure to either high-or low-caloric food, without actual eating. Independent of caloric condition, higher dietary restraint was associated with a decrease in body satisfaction after food exposure. With regard to weight satisfaction, however, the association between higher dietary restraint and decreased weight satisfaction was specific for the high-caloric condition. Thus, the actual eating of food is not necessary for decreased body and weight satisfaction to occur, suggesting an exposure-induced activation of dysfunctional cognitions in restrained eaters

‘I can’t accept that feeling’: Relationships between interoceptive awareness, mindfulness and eating disorder symptoms in females with, and at-risk of an eating disorder

Mindfulness based therapies (MBTs) for eating disorders show potential benefit for outcomes yet evidence is scarce regarding the mechanisms by which they influence remission from symptoms. One way that mindfulness approaches create positive outcomes is through enhancement of emotion regulation skills. Maladaptive emotion regulation is a key psychological feature of all eating disorders. The aim of the current study was to identify facets of emotion regulation involved in the relationship between mindfulness and maladaptive eating behaviours. In three cross-sectional studies, clinical (n=39) and non-clinical (n=137 and 119) female participants completed: 1) the Eating Disorder Inventory (EDI) eating specific scales (drive-for-thinness and bulimia) and the EDI psychological symptom scales (emotion dysregulation and interoceptive deficits); and 2) mindfulness, impulsivity, and emotion regulation questionnaires. In all samples mindfulness was significantly and inversely associated with EDI eating and psychological symptom scales, and impulsivity. In non-clinical samples interoceptive deficits mediated the relationship between mindfulness and EDI eating specific scales. Non-acceptance of emotional experience, a facet of interoceptive awareness, mediated the relationship between mindfulness and eating specific EDI scores. Further investigations could verify relationships identified so that mindfulness based approaches can be optimised to enhance emotion regulation skills in sufferers, and those at-risk, of eating disorders

Bayesian reinforcement learning with exploration

We consider a general reinforcement learning problem and show that carefully combining the Bayesian optimal policy and an exploring policy leads to minimax sample-complexity bounds in a very general class of (history-based) environments. We also prove lower bounds and show that the new algorithm displays adaptive behaviour when the environment is easier than worst-case

‘I can’t accept that feeling’: Relationships between interoceptive awareness, mindfulness and eating disorder symptoms in females with, and at-risk of an eating disorder

Mindfulness based therapies (MBTs) for eating disorders show potential benefit for outcomes yet evidence is scarce regarding the mechanisms by which they influence remission from symptoms. One way that mindfulness approaches create positive outcomes is through enhancement of emotion regulation skills. Maladaptive emotion regulation is a key psychological feature of all eating disorders. The aim of the current study was to identify facets of emotion regulation involved in the relationship between mindfulness and maladaptive eating behaviours. In three cross-sectional studies, clinical (n=39) and non-clinical (n=137 and 119) female participants completed: 1) the Eating Disorder Inventory (EDI) eating specific scales (drive-for-thinness and bulimia) and the EDI psychological symptom scales (emotion dysregulation and interoceptive deficits); and 2) mindfulness, impulsivity, and emotion regulation questionnaires. In all samples mindfulness was significantly and inversely associated with EDI eating and psychological symptom scales, and impulsivity. In non-clinical samples interoceptive deficits mediated the relationship between mindfulness and EDI eating specific scales. Non-acceptance of emotional experience, a facet of interoceptive awareness, mediated the relationship between mindfulness and eating specific EDI scores. Further investigations could verify relationships identified so that mindfulness based approaches can be optimised to enhance emotion regulation skills in sufferers, and those at-risk, of eating disorders

Dispositional mindfulness and reward motivated eating: The role of emotion regulation and mental habit

Evidence regarding the effectiveness of mindfulness based interventions (MBIs) for eating disorders, weight management and food craving is emerging and further studies are required to understand the underlying mechanisms of MBIs in these domains. The current study was designed to establish the role of specific mechanisms underlying the putative relationship between mindfulness and reward motivated eating. We predicted that mindfulness would be negatively related to features of reward motivated eating and that this association would be mediated by emotion regulation and habitual negative self-thinking. A cross-sectional survey measuring uncontrolled and emotional eating, mindfulness, emotion regulation and habitual negative self-thinking was completed by female and male meditators and non-meditators (N = 632). Lower levels of dispositional mindfulness were associated with difficulties in emotion regulation, habitual negative self-thinking and both emotional and uncontrolled eating. Difficulties in emotion regulation significantly mediated the mindfulness-uncontrolled eating relationship. Habitual negative self-thinking significantly mediated the mindfulness-emotional eating relationship. Participants with meditation experience reported greater levels of dispositional mindfulness, fewer difficulties with emotion regulation and habitual negative self-thinking and reduced uncontrolled eating tendencies, compared to non-meditators. The findings suggest that MBIs designed to change reward motivated eating and weight control should focus on emotion regulation and mental habits as underlying mechanisms