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Individual differences in responsiveness to caffeine occur even within a caffeine-consuming population, but the factors that mediate differential responsiveness remain unclear.
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Rationale: The relative contributions of different dopamine receptor subtypes to the discriminative stimulus effects of cocaine may be influenced by the training dose of cocaine. Substitution tests with dopamine receptor agonists ...
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Rationale: The relative contributions of different dopamine receptor subtypes to the discriminative stimulus effects of cocaine may be influenced by the training dose of cocaine. Substitution tests with dopamine receptor agonists have suggested that the role of dopamine D2-like receptors is diminished relative to that of D1-like receptors at a training dose of 3 mg/kg cocaine compared with a training dose of 10 mg/kg. Objectives: To test whether dopamine D2-like receptor antagonists were differentially effective at attenuating cocaine's discriminative stimulus effects at different training doses, and to test for the first time an antagonist that is selective for the dopamine D2 receptor within the D2-like receptor subfamily. Methods: Rats were trained to press one lever after receiving cocaine and another after receiving saline (maintaining >95% drug-appropriate responding). Three dopamine D2-like receptor antagonists (haloperidol, raclopride and L-741,626) were tested in rats trained at 3 mg/kg or 10 mg/kg cocaine. At the lower training dose, the D1-like receptor antagonist SCH 39166 was also tested. Results: The antagonists were not differentially effective between training groups: they all produced parallel, rightward shifts in cocaine's dose-effect function, indicating surmountable antagonism. Conclusions: The results demonstrate that D2-like receptor antagonists with different affinities for the various D2-like receptors can antagonise the discriminative stimulus effects of cocaine at two training doses. Importantly, antagonism by L-741,626 implies that stimulation of D2 receptors alone (not D3 or D4 receptors) is sufficient to mediate cocaine's discriminative stimulus effects. Finally, the claim that D1-like receptors are preferentially involved at low training doses of cocaine is only consistent with the current findings if indirect stimulation of D2 receptors by low doses of cocaine remains necessary for the expression of the D1-like receptor-mediated effect.
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Expected liking is an important determinant of food choice and there is some suggestion that liking expectations are stable over time. Here we examine the impact that a recent "disappointing" hedonic experience has on expected lik...
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Expected liking is an important determinant of food choice and there is some suggestion that liking expectations are stable over time. Here we examine the impact that a recent "disappointing" hedonic experience has on expected liking. In Study 1, we examine if a disappointing experience results in changes to expected liking one day after tasting and one week after tasting. In Study 2, we examine whether past frequency of eating a food determines whether a disappointing hedonic experience results in changes to expected liking. In Study 1, expected liking for a food was reduced 1 day after a disappointing experience, but not 1 week afterwards. In Study 2, past frequency of eating moderated whether expected liking for a food was reduced 1 week after a disappointing experience: expected liking of a infrequently eaten food was reduced, but not expected liking of a frequently eaten food. Liking expectations can be influenced by disconfirmatory hedonic experiences with a food product, but these effects are dependent upon the recency of the experience and the past frequency with which the food is eaten
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Novel ways to increase liking and intake of food are needed to encourage acceptance of healthier food. How enjoyable we remember food to have been is likely to be a significant predictor of food choice. Two studies examined whethe...
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Novel ways to increase liking and intake of food are needed to encourage acceptance of healthier food. How enjoyable we remember food to have been is likely to be a significant predictor of food choice. Two studies examined whether remembered enjoyment of eating a food can be increased and whether this makes individuals more likely to eat that food in the future. In Study One, a simple manipulation of instructing participants to rehearse what they found enjoyable about a food immediately after eating it was used to increase remembered enjoyment (relative to controls). In a separate study; Study Two, the effect of increasing remembered enjoyment on food choice was tested by examining whether the manipulation to increase remembered enjoyment resulted in participants choosing to eat more of a food as part of a later buffet lunch. The experimental manipulation increased remembered enjoyment for the food (Study One). A change in remembered enjoyment was shown to have a significant effect on the amount of a food participants chose to eat the following day for lunch (Study Two). The present studies suggest that remembered enjoyment can be increased via a simple act of rehearsal, resulting in a later increase in the amount of food chosen and eaten. Interventions based on altering remembered enjoyment of healthy food choices warrant further investigation. Copyright copyright The Authors 2011.
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Predictions about enjoyment of future experiences are influenced by recalling similar past experiences. However, little is known about the relationship between hedonic memories of past eating episodes and future eating behavior. W...
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Predictions about enjoyment of future experiences are influenced by recalling similar past experiences. However, little is known about the relationship between hedonic memories of past eating episodes and future eating behavior. We investigated recall of previous experiences of eating vegetables and the effect of recall on future predicted liking for and consumption of vegetables. British University undergraduate students were asked to retrieve memories of previous occasions when they ate vegetables and were asked to rate how enjoyable those experiences were (Study 1, n=54). The effect of different types of memory recall (including vegetable eating recall) and visualization of someone else eating vegetables (to control for priming effects) on predicted likelihood of choosing vegetables and predicted enjoyment of eating vegetables was examined (Study 2, n=95). Finally, the effect of recalling vegetable eating memories on actual food choice from a buffet was assessed (Study 3, n=63). It is reported that people recall positive memories of past vegetable consumption (P<0.05) and that reminding people of these experiences results in higher predicted future liking for vegetables (P<0.05) and choice of a larger portion size of vegetables (P<0.05) compared with recall of a personal nonfood memory, a nonvegetable food memory, or visualization of someone else enjoying eating vegetables (increase of approximately 70% in vegetable portion size compared to controls). The results suggest that recall of previous eating experiences could be a potential strategy for altering food choices. Copyright Copyright 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.
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Previously, it has been shown that synchronising actions with periodic pacing stimuli are unaffected by ageing. However, synchronisation often requires combining evidence across multiple sources of timing information. We have prev...
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Previously, it has been shown that synchronising actions with periodic pacing stimuli are unaffected by ageing. However, synchronisation often requires combining evidence across multiple sources of timing information. We have previously shown the brain integrates multisensory cues to achieve a best estimate of the events in time and subsequently reduces variability in synchronised movements (Elliott et al. in Eur J Neurosci 31(10):1828–1835, 2010). Yet, it is unclear if sensory integration of temporal cues in older adults is degraded and whether this leads to reduced synchronisation performance. Here, we test for age-related changes when synchronising actions to multisensory temporal cues. We compared synchronisation performance between young (N = 15, aged 18–37 years) and older adults (N = 15, aged 63–80 years) using a finger-tapping task to auditory and tactile metronomes presented unimodally and bimodally. We added temporal jitter to the auditory metronome to determine whether participants would integrate auditory and tactile signals, with reduced weighting of the auditory metronome as its reliability decreased under bimodal conditions. We found that older adults matched the performance of young adults when synchronising to an isochronous auditory or tactile metronome. When the temporal regularity of the auditory metronome was reduced, older adults’ performance was degraded to a greater extent than the young adults in both unimodal and bimodal conditions. However, proportionally both groups showed similar improvements in synchronisation performance in bimodal conditions compared with the equivalent, auditory-only conditions. We conclude that while older adults become more variable in synchronising to less regular beats, they do not show any deficit in the integration of multisensory temporal cues, suggesting that using multisensory information may help mitigate any deficits in coordinating actions to complex timing cues.
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Second-order cues are visual stimuli that are detectable by human observers, without eliciting a peak in Fourier energy that corresponds to their perceptual properties. The most commonly studied exemplars of second-order cues are ...
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Second-order cues are visual stimuli that are detectable by human observers, without eliciting a peak in Fourier energy that corresponds to their perceptual properties. The most commonly studied exemplars of second-order cues are those defined by modulation of local contrast (CM). It is widely accepted that such cues are initially detected separately from first-order, luminance modulated (LM), cues. However, after-effects have been shown to transfer between first- and second-order cues (LM and CM, respectively). This suggests the existence of a late link in the mechanisms that subserve their processing. To extend the investigation of the mechanisms for processing second-order cues we consider cues defined by modulations in local orientation (OM). Using a tilt-after-effect (TAE) paradigm, we found partial transfer of adaptation between LM and OM cues, confirming the presence of a link between first and second-order cues. Furthermore, we found a partial transfer of TAE between OM and CM cues. These results suggest that, at or before the site of adaptation, information from all visual cues is combined. However, as transfer of adaptation is below 100% in all cases, this is only a partial integration of information.
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This article discusses four different scenarios to specify increasingly complex mechanisms that enable increasingly flexible social interactions. The key dimension on which these mechanisms differ is the extent to which organisms ...
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This article discusses four different scenarios to specify increasingly complex mechanisms that enable increasingly flexible social interactions. The key dimension on which these mechanisms differ is the extent to which organisms are able to process other organisms' intentions and to keep them apart from their own. Drawing on findings from ecological psychology, scenario 1 focuses on entrainment and simultaneous affordance in ‘intentionally blind’ individuals. Scenario 2 discusses how an interface between perception and action allows observers to simulate intentional action in others. Scenario 3 is concerned with shared perceptions, arising through joint attention and the ability to distinguish between self and other. Scenario 4 illustrates how people could form intentions to act together while simultaneously distinguishing between their own and the other's part of a joint action. The final part focuses on how combining the functionality of the four mechanisms can explain different forms of social interactions. It is proposed that basic interpersonal processes are put to service by more advanced functions that support the type of intentionality required to engage in joint action, cultural learning, and communication.
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Cigarette smoking is highly prevalent in people diagnosed with depression, and depressed smokers are less likely to quit. Examining depressed smokers’ responses to smoking will help determine the role of depression in maintaining...
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Cigarette smoking is highly prevalent in people diagnosed with depression, and depressed smokers are less likely to quit. Examining depressed smokers’ responses to smoking will help determine the role of depression in maintaining cigarette smoking.
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Abstract. We report an experiment in which participants made gender judgments (male or female) to faces. There were three groups of faces: unfamiliar, familiar (celebrities), and a set which had been learned earlier by the partici...
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Abstract. We report an experiment in which participants made gender judgments (male or female) to faces. There were three groups of faces: unfamiliar, familiar (celebrities), and a set which had been learned earlier by the participants during the experimental session. The principal purpose of this study was to establish an indirect measure of assessing whether faces have become familiar through learning that does not require overt recognition. Bruce and Young's (1986 British Journal of Psychology 77 305 - 327) model of face recognition suggests face-processing tasks are independent of one another and so familiarity should have no impact on the time taken to perform gender decisions. However, recent studies have suggested that some face processes are not completely independent. A gender judgment is a simple task which would be useful in face-learning experiments. We examined whether exposure to previously novel faces facilitates a later gender decision to those faces. During a learning stage, participants viewed a set of unfamiliar faces. At test, participants were able to assign gender faster to previously familiar (famous) faces and learned faces than they were to unfamiliar faces. Therefore familiarity can influence the speed at which gender is analysed. We explain our findings with reference to the Burton et al (1990 British Journal of Psychology 81 361 - 380) interactive activation and competition (IAC) model of face recognition and discuss how the gender judgment might be employed as a means of tracking the acquisition of familiarity in face-learning studies.
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