Several researchers have hypothesized that implicit memory remains stable across the lifespan. Empirical support with children has been difficult to interpret due to methodological weaknesses including baseline variation, floor and ceiling effects, and lack of experimental dissociations. A new measure of repetition priming, the picture fragment completion task, was developed to account for these weaknesses while being appropriate for both children and adults. Adults and children aged 4, 6, and 8 (N = 156) completed either the picture fragment completion task or an explicit memory test made from same materials. Subjects of all ages performed equally on the priming test while performance increased with age on the explicit memory test. For all ages, the levels of processing manipulation affected only the explicit memory test. Thus, subjects were not using effortful strategies on the priming test. These results form a solid foundation for studying other developmental issues in implicit memory.

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Apolipoprotein E-knockout (apoEKO) mice were characterized behaviorally to evaluate the impact of apolipoprotein E deficiency on spatial learning and memory function at different ages. Wild type and knockout mice were tested in two tasks assessing spatial memory function, Morris water maze (MWM) and Radial arm maze (RAM). Both young and aged apoEKO mice backcrossed six generations displayed deficits in the MWM. However, young and aged 10th generation apoEKO mice did not display any deficits in the MWM or the RAM when spatial cues that could be used to solve these tasks were provided. Removal of spatial cues after training had occurred also did not result in an impairment. In contrast, apoEKO mice were impaired when spatial cues were removed from the beginning of training. This result suggests that these mice are less able to utilize non-spatial cues to solve these tasks. The impairments observed in the MWM and RAM were not the result of impaired reference memory function, but rather appeared to arise from a dysfunction in working memory. Additional tests assessing sensorimotor gating function (Prepulse inhibition), and emotionality (the Open field, the Elevated plus maze) suggested that these cognitive deficits did not arise from alterations in sensorimotor gating function or emotionality, as both young and aged apoEKO mice performed at levels similar to those observed in their aged C57BL/6J control groups.

No description available.

It is a tenable theory that there are marked individual differences in the facility with which people apprehend novel and enigmatic features in their perceptual fields and invest these data with probable or plausible meanings. [...]

<p> Research on social judgment typically emphasizes one of three processes that enable unequivocal understanding of events with ambiguous causality. In the <i>social influence perspective</i>, people are susceptible to the interpretations offered by others. In the <i>explicit attitudes perspective</i>, people interpret events in line with their consciously held attitudes and values. In the <i>implicit attitudes perspective</i>, people interpret events in line with unconscious biases. The model investigated in the present study assumes that these processes vary in salience depending on people&rsquo;s mindset. When an event is encoded in high-level terms (i.e., its consequences), people&rsquo;s judgments reflect their explicit attitudes. When encoded in low-level terms (i.e., its details), however, such attitudes are less accessible, rendering people susceptible to social influence. In the absence of social influence, people with a lower-level mindset form judgments that reflect their relevant implicit attitudes. These hypotheses were tested in the context of an altercation between an African-American and a White male for which responsibility could reasonably be allocated to either party. Participants with low versus high implicit racial bias toward Blacks read a narrative concerning this altercation under either a low-level or a high-level mindset and then read a summary that blamed one of the parties or they did not read a summary. As predicted, low-level participants allocated responsibility to the African-American if they had a high implicit racial bias and to the White if they had a low implicit racial bias, regardless of the summary manipulation. Contrary to prediction, however, high-level participants&rsquo; allocation of responsibility did not reflect their explicit prejudicial attitudes. Instead, they corrected for their implicit biases in their trait inferences and affective reactions, in line with research suggesting that a high-level mindset promotes self-regulatory processes in social judgment.</p>

<p> Few studies have examined differences between online and offline gamblers, with no study to date enlisting the participation of online gamblers in a laboratory-based study. Moreover, research indicates that there is a link between escape and problem gambling, however, no study to date has examined this relationship in online gamblers using an experimental design. The current study is the first to address these gaps in the literature. All 420 participants participated in the non-experimental phase of the study, and 50 participants participated in the experimental phase. All participants completed a demographics form, SOGS, PGSI, GFA-R, BDI-SF, discounting task, and a gambling motivations questionnaire. In the experimental phase, participants' mood state was manipulated using hypothetical scenarios before gambling. The results indicated that online gamblers had a higher rate of problem-gambling severity than offline gamblers, and that online gamblers have used gambling to escape to a greater degree than offline gamblers. In terms of differences in the gambling behavior of online and offline gamblers, online gamblers were found to have played more hands and committed more errors than offline gamblers. No statistically significant results were found across mood conditions, or when the interaction between participants' gambler status and mood condition was examined, although trends in the hypothesized direction were observed. No statistically significant group differences were observed when online gamblers' rate of discounting certain outcomes was compared to offline gamblers' rates. Taken together, these results suggest that some of the differences between online and offline gamblers may help explain the higher prevalence of problem gambling among online gamblers. Although gambling to escape was found to be positively correlated with problem-gambling severity, the experimental results did not support this finding. Future studies should investigate the relationship between escape and problem gambling in online gamblers by using a different manipulation. A more knowledgeable understanding of the differences between online and offline gamblers will lead to better treatment outcomes for individuals who suffer from a gambling addiction.</p>

These analyses test the hypothesis that contour integration is distinct from simple, non-random pattern recognition, and that it can be studied fruitfully using a novel combination of methodologies. Real, human observers and ideal observers perform a classification task in which the two stimulus patterns are systematically corrupted by noise to determine the effect of that noise on observers' responses. This technique, response classification, is used to determine how observers use the available information in an array of line elements to discriminate between an aligned contour and a non-random (orthogonal) pattern. The comparison between performance of several ideal observers and the human observers reveals that template-matching models might not account entirely for the human observers' responses. Beyond showing that human observers perform the task using the local relations between neighboring elements, we also determine the circumstances under which grouped pairs of elements are integrated perceptually into more extended contours. These circumstances are related theoretically to co-occurrence statistics derived from natural images between pairs of small line elements using the parameters of distance, orientation difference, and direction. The complete set of analyses further our understanding of how humans perceive visual contour.

Duration is a fundamental characteristic of events, intervals, and episodes. Its estimation is affected by a multitude of non-temporal factors such as whether the duration interval is filled or empty, its modality, and cognition during the interval. The central question addressed in this dissertation is whether the estimated duration of a stimulus varies with its pitch and, if so, whether the relation depends on the type of the stimulus, its duration, and of its degree of change. The range effect: the phenomenon that for the same duration sounds with larger pitch range are estimated longer than sounds with smaller pitch range, was explored in a series of ten experiments. The range effect was smaller for small durations and increased as duration increased up to 900 ms, then decreased. The effect was larger for ascending than for descending sounds and for glides than for staircase and discrete sounds. Furthermore, it was demonstrated with both magnitude estimation and comparison. These results have implications for time perception models such as Block's attentional-gate model.

I report five experiments in an exploratory study to investigate the perceptual grouping processes by better understanding how a simple pattern of dots comes to be represented in visual memory. Subjects were briefly shown a random set of point-like dots which were then masked and subsequently reappeared with a possible added or deleted dot. Subjects detected changes to peripheral dots more reliably than changes to interior dots, even those much closer to fixation. The most peripheral points appear to be objectized in a process that might be analogized as shrink wrapping. The circumscribed shape was memorable and easily recalled despite brief presentations. These data suggest a preattentive perceptual process beginning in the periphery and proceeding inward toward fixation as the visual system records the shape of the pattern.