Dual-target search for high and low prevalence X-ray threat targets

Recent studies have shown that the prevalence of target presentation in visual search has an impact on target detection rates, and also that searching for two targets leads to a decrement in performance (the “dual-target cost”). In the present experiments, we added to previous work that has examined the interaction between the prevalence effect and dual-target cost, and also to previous work that has examined a full range of prevalence levels. We found no interaction between the dual-target cost and prevalence effect, though the response criterion in dual-target search did interact with target prevalence in an unexpected manner. Furthermore, we detected anasymmetry in the prevalence effect: It was more marked for high than low prevalence. Implications for real-world tasks are discussed.     

From a fixation on sports to an exploration of mechanism: The past,present, and future of hot hand research

We review the literature on the hot hand fallacy by highlighting the positive and negative aspects of hot hand research over the past 20 years, and suggesting new avenues of research. Many researchers have focused on criticising Gilovich et al.'s claim that the hot hand fallacy exists in basketball and other sports, instead of exploring the general implications of the hot hand fallacy for human cognition and probabilistic reasoning. Noting that researchers have shown that people perceive hot streaks in a gambling domain in which systematic streaks cannot possibly exist, we suggest that researchers have paid too much attention to investigating the independence of outcomes in various sporting domains. Instead, we advocate a domain-general mechanistic approach to understanding the hot hand fallacy, and conclude by suggesting approaches that might refocus the literature on the important general implications of the hot hand fallacy for human probabilistic reasoning.     

Change detection inflates confidence on a subsequent recognition task

A face viewed under good encoding conditions is more likely to be remembered than a face viewed under poor encoding conditions. In four experiments we investigated how encoding conditions affected confidence in recognising faces from line-ups. Participants performed a change detection task followed by a recognition task and then rated how confident they were in their recognition accuracy. In the first two experiments the same faces were repeated across trials. In the final two experiments novel faces were used on each trial. Target-present and target-absent line-ups were utilised. In each experiment participants had greater recognition confidence after change detection than after change blindness. The finding that change detection inflates confidence, even for inaccurate recognitions, indicates recognition certainty can be a product of perceived encoding conditions rather than authentic memory strength.     

Behavior-Based Assessment of the Auditory Abilities of Brushtail Possums

Brushtail possums (Trichosurus vulpecula) were trained to press a right lever when a tone was presented (a tone‐on trial) and a left lever when a tone was not presented (a tone‐off trial) to gain access to food. During training the tone was set at 80 dB(A), with a frequency of 0.88 kH for 3 possums and of 4 kH for the other 2. Once accuracy was over 90% correct across five consecutive sessions, a test session was conducted where the intensity of the tone was reduced by 8 dB(A) over blocks of 20 trials until accuracy over a block fell below 60%. After each test session, training sessions were reintroduced and continued until accuracy was again over 90%, when another test session was conducted. This process continued until there were at least five test sessions at that tone frequency. The same procedure was then used with frequencies of 0.20, 0.88, 2, 4, 10, 12.5, 15, 20, 30, and 35 kHz. Percentage correct and d' decreased approximately linearly for all possums as tone intensity reduced. Both sets of lines were shallowest at the higher frequencies and steepest at the lower frequencies. Hit and false alarm rates mirrored each other at high frequencies but were asymmetric at lower frequencies. Equal d' contours showed that sensitivity increased from 2 to 15 kHz and continued to be high over 20 to 35 kHz. The possums remained sensitive to the 20 to 35 kHz tones even at low intensities. The present study is the first to report the abilities of possum to detect tones over this range of frequencies and its results support the findings of a microelectrode mapping survey of possums' auditory cortex.     

Estimating the growth of internal evidence guiding perceptual decisions

Perceptual decision-making is thought to involve a gradual accrual of noisy evidence. Temporal integration of the evidence reduces the relative contribution of dynamic internal noise to the decision variable, thereby boosting its signal-to-noise ratio. We aimed to estimate the internal evidence guiding perceptual decisions over time, using a novel combination of external noise and the response signal methods. Observers performed orientation discrimination of patterns presented in external noise. We varied the contrast of the patterns and the delay at which observers were forced to signal their decision. Each test stimulus (patterns and noise sample) was presented twice. Across two experiments we varied the availability of the visual stimulus for processing. Observer model analyses of discrimination accuracy and response consistency to two passes of the same stimulus, suggested that there was very little growth in the internal evidence. The improvement in accuracy over time characterised by the speed-accuracy trade-off function predominantly reflected a decreasing proportion of non-visual decisions, or pure guesses. There was no advantage to having the visual patterns visible for longer than 80 ms, indicating that only the visual information in a short window after display onset was used to drive the decisions. The remarkable constancy of the internal evidence over time suggests that temporal integration of the sensory information was very limited. Alternatively, more extended integration of the evidence from memory could have taken place, provided that the dominant source of internal noise limiting performance occurs between-trials, which cannot be reduced by prolonged evidence integration.     

反馈对注意缺损多动障碍儿童错误监控能力的影响

研究选取了注意缺损多动障碍(ADHD)儿童39名,正常儿童40名,采用两项选择任务,考察在无反馈和有反馈的情况下,ADHD儿童的错误监控能力是否存在缺损。结果发现,(1)无论是否提供反馈,与正常儿童相比,ADHD儿童的错误察觉能力正常,但是错误更正能力落后,这可能是由于ADHD儿童动作调节控制能力落后导致的;(2)反馈提高了ADHD儿童和正常儿童的认知加工速度,但同时降低了他们的警醒水平,导致错误监控能力下降。     

Detection of change in shape: an advantage for concavities

Shape representation was studied using a change detection task. Observers viewed two individual shapes in succession, either identical or one a slightly altered version of the other, and reported whether they detected a change. We found a dramatic advantage for concave compared to convex changes of equal magnitude. Observers were more accurate when a concavity along the contour was introduced, or removed, compared to a convexity. This result sheds light on the underlying representation of visual shape, and in particular the central role played by part-boundaries. Moreover, this finding shows how change detection methodology can serve as a useful tool in studying the specific form of visual representations.     

Social-class indicators differentially predict engagement in prevention vs. detection behaviours

Objective: Few systematic studies have examined the contexts in which social-class variables will predict engagement in health-relevant behaviours. The current research examined whether the impact of social-class on health behaviours depends upon how social-class is assessed and the category of health behaviour under consideration.

Method: Our sample was drawn from the Health Information National Trends Survey in 2012 (N = 3959). Participants reported their income and education as well as their engagement in a variety of prevention and detection behaviours.

Results: Consistent with our hypothesised framework, we found that income predicted engagement in a variety of detection behaviours above and beyond education, whereas education predicted engagement in a variety of prevention behaviours above and beyond income.

Conclusions: Our findings suggest that income and education operate on health behaviours via different pathways and have implications for public health policy and intervention.