The Time-Course of Attentional Bias to Symptom-Related Words in Functional Gastrointestinal Disorders: An EEG Study

This item is only available electronically.Research has highlighted the role of psychological processes in functional gastrointestinal disorders (FGIDs). The presence of potentially unconscious attentional bias toward gastrointestinal symptom-related words might attest to the contribution of psychological factors in FGIDs, but few studies have addressed attentional bias in FGID-sufferers, specifically. This study aimed to use electroencephalography to examine unconscious and conscious attentional bias to symptom-related nouns in FGID-sufferers and explore how EEG indices of attention correlate with symptom severity and health anxiety. Thirty FGIDsufferers and 30 controls completed a fast-presentation task using an oddball paradigm to measure unconscious attention, a silent reading task measuring unconscious and conscious attention, and scales measuring health-related and psychosocial states. A series of symptomrelated, negative, and neutral nouns were used in both EEG tasks. One-way t-tests, comparing the signal-to-noise ratio to 1.6, were used to analyse the fast presentation task data, while mixed ANOVAs were performed on event-related potentials indicative of unconscious attention (P100 and early posterior negativity) and conscious attention (N400 and late posterior positivity) in the silent reading task. An unconscious attentional bias was not observed in either EEG task. However, vigilance for negative nouns, followed by avoidance of negative and sustained processing of symptom-related nouns was observed across groups in the silent reading task, and the strength of this vigilance-avoidance pattern correlated with health anxiety. Conversely, symptom severity did not correlate with attentional bias. A deeper understanding of the time-course of attentional bias in FGID-sufferers could inform the design and application of psychological interventions aimed at treating FGIDs.Thesis (B.PsychSc(Hons)) -- University of Adelaide, School of Psychology, 202

Achieving innovation and global competitiveness through research and development tax incentives: lessons for Australia from the UK

Paper presented at 24th Annual Conference of the Australasian Tax Teachers Association, 16-17 January 2012, University of Sydney. Final version published in Australian Tax Foru

Human Choices Between Variable and Fixed Rewards in Hypothetical Variable-Delay and Double-Reward Discounting Procedures

Prior research has shown that nonhumans show an extreme preference for variable- over fixed-delays to reinforcement. This well-established preference for variability occurs because a reinforcer’s strength or “value” decreases according to a curvilinear function as its delay increases. The purpose of the present experiments was to investigate whether this preference for variability occurs with human participants making hypothetical choices. In three experiments, participants recruited from Amazon Mechanical Turk made choices between variable and fixed monetary rewards. In a variable-delay procedure, participants repeatedly chose between a reward delivered either immediately or after a delay (with equal probability) and a reward after a fixed delay (Experiments 1 and 2). In a double-reward procedure, participants made choices between an alternative consisting of two rewards, one delivered immediately and one after a delay, and a second alternative consisting of a single reward delivered after a delay (Experiments 1 and 3). Finally, all participants completed a standard delay-discounting task. Although we observed both curvilinear discounting and magnitude effects in the standard discounting task, we found no consistent evidence of a preference for variability—as predicted by two prominent models of curvilinear discounting (i.e., a simple hyperbola and a hyperboloid)—in our variable-delay and double-reward procedures. This failure to observe a preference for variability may be attributed to the hypothetical, rule-governed nature of choices in the present study. In such contexts, participants may adopt relatively simple strategies for making more complex choices

Tests of an Indifference Rule in Variable-Delay and Double-Reward Choice Procedures with Humans

Four-hundred and fifty participants were recruited from Amazon Mechanical Turk across three experiments to test the predictions of a hyperbolic discounting equation in accounting for human choices involving variable delays or multiple rewards (Mazur, 1984, 1986). In Experiment 1, participants made hypothetical choices between two monetary alternatives, one consisting of a fixed delay and another consisting of two delays of equal probability (i.e., a variable-delay procedure). In Experiment 2, participants made hypothetical monetary choices between a single, immediate reward and two rewards, one immediate and one delayed (i.e., a double-reward procedure). Experiment 3 also used a double-reward procedure, but with two delayed rewards. Participants in all three experiments also completed a standard delay-discounting task. Finally, three reward amounts were tested in each type of task ($100,$1000, and $5000). In the double-reward conditions (Experiments 2 and 3), the results were in good qualitative and quantitative agreement with Mazur’s model (1984, 1986). In contrast, when participants made choices involving variable delays (Experiment 1), there was relatively poor qualitative and quantitative agreement with this model. These results, along with our previous findings, suggest the structure of questions in hypothetical tasks with humans can be a strong determinant of the choice pattern

Systematic Evaluation of Variables that Contribute to Noncompliance: A Replication and Extension

The effects of time-out and escape extinction were examined with 2 preschoolers after we identified variables that may have resulted in noncompliance. Results of a functional analysis showed that noncompliance was highest in the escape condition for both participants. During the treatment evaluation, escape extinction resulted in greater reductions in noncompliance relative to time-out

Effects of Reward Magnitude Frames on Measures of Delay Discounting in a Hypothetical Money Scenario

The current study analyzed the effects of three frames of reward magnitude – quantity, volume, and duration – on the rate at which college students discounted hypothetical, delayed monetary rewards. Hypothetical scenarios were presented using the fill-in-the-blank discounting questionnaire and participants made choices between immediate and delayed hypothetical monetary rewards. Scenarios framed the monetary choices as (a) quantity of dollar bills, (b) height (inches) of a stack of dollar bills, and (c) duration of time spent in a hypothetical cash machine to collect dollar bills. For each scenario, participants’ subjective values were used to calculate the area under the curve (AuC). Framing resulted in a moderate effect size: the duration frame yielded significantly smaller AuC values compared to the quantity and volume frames. Thus, the framing of reward magnitude was a significant variable in controlling discounting rates for hypothetical, delayed monetary rewards. Subsequent investigations should be aware of the independent effects of the reward magnitude frames on delay discounting rates

Findings on the impact of self assessment on the compliance behaviour of individual taxpayers in Malaysia: a case study approach

Article published in Journal of Australian Taxation by Monash University, Department of Business Law and TaxationThis article presents research findings based on the conduct of 74 case studies with individual taxpayers at the time that self assessment was introduced in Malaysia. Generally, it was found that subjects now exercised more care when filing their income tax returns to ensure that they only paid the tax required and that penalties were not imposed for non-compliance

On the Scaling Interpretation of Exponents in Hyperboloid Models of Delay and Probability Discounting

Previously, we (McKerchar et al., 2009) showed that two-parameter hyperboloid models (Green and Myerson, 2004; Rachlin, 2006) provide significantly better fits to delay discounting data than simple, one-parameter hyperbolic and exponential models. Here, we extend this effort by comparing fits of the two-parameter hyperboloid models to data from a larger sample of participants (N= 171) who discounted probabilistic as well as delayed rewards. In particular, we examined the effects of amount on the exponents in the two hyperboloid models of delay and probability discounting in order to evaluate key theoretical predictions of the standard psychophysical scaling interpretation of these exponents. Both the Rachlin model and the Green and Myerson model provided very good fits to delay and probability discounting of both small and large amounts at both the group and individual levels (all R2s \u3e .97 at the group level; all median R2s \u3e .92 at the individual level). For delay discounting, the exponent in both models did not vary as a function of delayed amount, consistent with the psychophysical scaling interpretation. For probability discounting, however, the exponent in both models increased as the probabilistic amount increased—a finding inconsistent with the scaling interpretatio

Re-Interpreting Melton’s Study of Gallery Density and Visitor Attention

The works of Edward Robinson and Arthur Melton conducted in the 1920s and 1930s are often cited, but rarely read. The focus of this article is on one of Melton’s (1935) classic visitor studies, re-examined in terms of several explanatory mechanisms including a decision-making model of visitor attention. Melton varied the number of paintings in a gallery from 6 to 36 in increments of 6. As the number of paintings increased, the proportion of paintings actually viewed decreased; however, the average viewing time per painting remained constant. Melton’s findings of decreased attention are discussed in terms of four possible explanations: perceptual distraction, selective choice, object satiation, and fatigue. While fatigue, satiation, and distraction have all been frequently discussed in the visitor literature, selective choice has not. The implications of the attention-value model for selective choice is described in light of Melton’s study

Hyperboloid Discounting of Delayed Outcomes: Magnitude Effects and the Gain-Loss Asymmetry

For more than 20 years, a plethora of research has been conducted on the discounting of delayed rewards. In contrast, there has been relatively little research on the discounting of delayed aversive outcomes (e.g., monetary losses). The present study examined the discounting of delayed hypothetical gains and losses by 55 college undergraduates at two monetary amounts, $1,000 and$25,000. A simple hyperbola generally provided very poor fits to the data. In contrast, a hyperboloid provided much better fits to the discounting of all outcomes, and its exponent was frequently less than unity. Although the rate of discounting was greater for the small gain than for the large gain (i.e., a magnitude effect), the rate of discounting the small and large loss was not significantly different. This differential effect of amount resulted in a gain-loss asymmetry at the small amount (i.e., small gains discounted more than small losses), but not at the large amount (i.e., large gains discounted similarly to large losses). Collectively, these findings suggest that similar, but separate processes underlie the discounting of delayed gains and losses