No description available.

No description available.

Contemporary theories of causal induction have focussed largely on the question of how evidence in the form of covariations between causes and effects is used to compute measures of causal strength. A very important precursor enabling such computations is that the reasoner notices that a cause and effect have co-occurred. Standard laboratory experiments have usually bypassed this problem by presenting participants directly with covariational information. As a result, relatively little is known about how humans identify causal relations in real time. What evidence exists, however, paints a rather unflattering picture of human causal induction and converges to the conclusion that humans cannot identify causal relations if cause and effect are separated by more than a few seconds. Associative learning theory has interpreted these findings to indicate that temporal contiguity is essential to causal inference. I argue instead that contiguity is not essential, but that the influence of time in causal inference is crucially dependent on people's beliefs and expectations about the timeframe of the causal relation in question. First I demonstrate that humans are capable of dissociating temporal contiguity from causal strength; more specifically, they can learn that a given event exerts a stronger causal influence when it is temporally separated from the effect than when it is contiguous with it. Then I re-investigate a paradigm commonly used to study the effects of delay on human causal induction. My experiments employed one crucial additional manipulation regarding participants' awareness of potential delays. This manipulation was sufficient to reduce the detrimental effects of delay. Three other experiments employed a similar strategy, but relied on implicit instructions about the timeframe of the causal relation in question. Overall, results support the hypothesis that knowledge mediates the timeframe of covariation assessment in human causal induction. Implications for associative learning and causal power theories are discussed.

No description available.

No description available.

The central purpose of this study is to ascertain the function of immediate verbal feedback after each response on learning a paired associative task with normal and retarded subjects.

<p>Human learning and memory relies on a broad network of neural substrates, and is sensitive to a range of environmental factors and behaviors. The present studies are designed to investigate the modulation of active exploration behaviors in humans. In the current work, we operationalize exploration in two ways: participants’ spatial navigation (using a computer mouse) in environments containing rewarding and informative stimuli, and participants’ eyegaze activity while viewing images on a computer screen. The study described in Study 1 investigates the relationship between spatial exploration and reward, using participants’ reported anxiety levels to predict between-subject variability in vigor and information-seeking. The study described in Study 2 investigates the relationship between cue-outcome predictive validity and eyegaze behavior during learning; additionally, we test the extent to which differing states of expectation drive differences in eyegaze behavior to novel images. The study described in Study 3 expands on the questions raised in Study 2: using functional imaging and eyetracking, we investigate the relationship between predictive validity, gaze, and the neural systems supporting active exploration. Taken together, the findings in the present study suggest that emerging certainty in reward outcomes, rather than uncertainty, drives exploration and associative learning for events and their outcomes as well as encoding into long-term memory.</p> / Dissertation

Recent research has found that subjects learning a list of paired-associates under conditions requiring one-trial learning are capable of learning a list of paired items in as few a number of trials as subject learning similar lists of paired-associates under a condition using repetition.

We review some computational aspects of motor control. The problem of trajectory control is phrased in terms of an efficient representation of the operator connecting joint angles to joint torques. Efficient look-up table solutions of the inverse dynamics are related to some results on the decomposition of function of many variables. In a biological perspective, we emphasize the importance of the constraints coming from the properties of the biological hardware for determining the solution to the inverse dynamic problem.

Increased impulsivity and alterations in reward sensitivity co-occur in many psychiatric disorders. Moreover, individuals reporting more impulsive traits are less efficient in learning stimulus-reward associations. This suggests that impulsivity and reward sensitivity may be linked, consistent with evidence that the orbital frontal cortex (OFC) is implicated in both processes. This study examined the relationship between impulsive traits, assessed by the Barratt Impulsiveness Scale (BIS) and the Eysenck (EIQ), and performance on three behavioral tasks that measure impulsivity and reward sensitivity. The tasks included a Conditioned Pattern Preference (CPP) task, which measures the preference for abstract visual cues as an index of implicit emotional learning, a Probabilistic Reversal Learning (PRL) task that assessed the ability to alter behaviour when reward contingencies change and an Emotional Stroop task which assessed attentional control in response to emotionally salient stimuli. This study provided novel information on the relationship between processes that mediate impulsivity and reward sensitivity. In brief, subjects that were considered to have some explicit knowledge of experimental conditions showed a higher preference formation for the pattern paired with the reward on 90% of the conditioning trials. Although there was no overall effect of impulsivity, the medium impulsive group displayed the strongest preference formation (highest score for the 90% pattern and lowest score for the 10% pattern) compared to the low and high groups. Furthermore, there was an overall effect of Word Category in that participants made more errors for the emotional words (positive and negative) than the neutral words. There was no overall effect of Impulsivity on Stroop performance in this sample. Finally, for the PRL task more participants in the high impulsive group did not meet criterion for the Acquisition stage while more low impulsive subjects did not meet reversal criterion. Furthermore, high impulsive subjects made more overall errors in the Acquisition stage but not Reversal stage. In brief, low and high impulsive subjects performed sub-optimally on the CPP and PRL tasks but not on the Stroop task. This pattern reflects an inverted-U shaped relationship of the effects of impulsivity on associative learning. / Thesis (Master, Psychology) -- Queen's University, 2010-02-05 13:33:27.076