“多少”概念发展的研究

采用数量判定任务,分别用2～30和5～100范围内点子图为刺激,研究个体“多”和“少”概念的发展。结果发现：在5～100点子条件下,随年龄的增长,个体“多”概念的判断值、“少”概念的判断值、“多”“少”概念的临界值均显著增大;7～9岁是个体“多少”概念发展的转折期;个体对“多少”概念的认知具有相对性;在本实验的两种条件下,随年龄增长,个体“多”概念的判断值、“少”概念的判断值、“多”“少”概念的临界值逐渐趋于刺激点子数最大值的2/3、1/3、1/2,“多”概念与“少”概念判断的不确定距离逐渐趋于刺激点子数最大变化范围的1/3或略小于1/3。     

Likable co-witnesses increase eyewitness accuracy and decrease suggestibility

This study examines the impact of likability on memory accuracy and memory conformity between two previously unacquainted individuals. After viewing a crime, eyewitnesses often talk to one another and may find each other likable or dislikable. One hundred twenty-seven undergraduate students arrived at the laboratory with an unknown confederate and were assigned to a likability condition (i.e., control, likable or dislikable). Together, the pair viewed pictures and was then tested on their memory for those pictures in such a way that the participant knew the confederate's response. Thus, the participant's response could be influenced both by his or her own memory and by the answers of the confederate. Participants in the likable condition were more accurate and less influenced by the confederate, compared with the other conditions. Results are discussed in relation to research that shows people are more influenced by friends than strangers and in relation to establishing positive rapport in forensic interviewing.     

How do we convert a number into a finger trajectory?

How do we understand two-digit numbers such as 42? Models of multi-digit number comprehension differ widely. Some postulate that the decades and units digits are processed separately and possibly serially. Others hypothesize a holistic process which maps the entire 2-digit string onto a magnitude, represented as a position on a number line. In educated adults, the number line is thought to be linear, but the “number sense” hypothesis proposes that a logarithmic scale underlies our intuitions of number size, and that this compressive representation may still be dormant in the adult brain. We investigated these issues by asking adults to point to the location of two-digit numbers on a number line while their finger location was continuously monitored. Finger trajectories revealed a linear scale, yet with a transient logarithmic effect suggesting the activation of a compressive and holistic quantity representation. Units and decades digits were processed in parallel, without any difference in left-to-right vs. right-to-left readers. The late part of the trajectory was influenced by spatial reference points placed at the left end, middle, and right end of the line. Altogether, finger trajectory analysis provides a precise cognitive decomposition of the sequence of stages used in converting a number to a quantity and then a position.     

Numerical approximation abilities correlate with and predict informal but not formal mathematics abilities

Previous research has found a relationship between individual differences in children’s precision when nonverbally approximating quantities and their school mathematics performance. School mathematics performance emerges from both informal (e.g., counting) and formal (e.g., knowledge of mathematics facts) abilities. It remains unknown whether approximation precision relates to both of these types of mathematics abilities. In the current study, we assessed the precision of numerical approximation in 85 3- to 7-year-old children four times over a span of 2 years. In addition, at the final time point, we tested children’s informal and formal mathematics abilities using the Test of Early Mathematics Ability (TEMA-3). We found that children’s numerical approximation precision correlated with and predicted their informal, but not formal, mathematics abilities when controlling for age and IQ. These results add to our growing understanding of the relationship between an unlearned nonsymbolic system of quantity representation and the system of mathematics reasoning that children come to master through instruction.     

Force Control Is Greater in the Upper Compared With the Lower Extremity

The authors investigated whether force control is similar between the upper and lower limbs and between contractions that involve 1 or 2 joints. Six volunteers (27.5 ± 11.2 years of age) attempted to produce consistent discrete rapid force responses of 30, 60, and 90 N by using 6 different body postures, 3 with the upper and 3 with the lower limb. One of the postures for each limb involved 2 joints. The standard deviation of peak force and impulse (aggregate of the force-time curve) was significantly greater (?25%) for the lower limb than for the upper limb (p < .01). Contractions that involved 1 or 2 joints within a limb had similar variability. Therefore, the upper limb might have better control of force than the lower limb because of its extensive use in fine motor tasks in daily activities.     

Eye-Hand Coordination in Rhythmical Pointing

The authors investigated the relation between hand kinematics and eye movements in 2 variants of a rhythmical Fitts's task in which eye movements were necessary or not necessary. P. M. Fitts's (1954) law held in both conditions with similar slope and marginal differences in hand-kinematic patterns and movement continuity. Movement continuity and eye—hand synchronization were more directly related to movement time than to task index of difficulty. When movement time was decreased to fewer than 350 ms, eye—hand synchronization switched from continuous monitoring to intermittent control. The 1:1 frequency ratio with stable π/6 relative phase changed for 1:3 and 1:5 frequency ratios with less stable phase relations. The authors conclude that eye and hand movements in a rhythmical Fitts's task are dynamically synchronized to produce the best behavioral performance.     

Decision Strategies and the Confidence–Accuracy Relationship in Face Recognition

The decision strategy used to select a choice set from an array of alternative options is known to affect the composition of the final choice set. Specifically, individuals incorporate more answers into their choice set when it is created by eliminating implausible items than when the set is created through the inclusion of plausible options. This difference is accounted for in a decision framework that posits a general reluctance to change the status quo (i.e., actively include or exclude an item). We extended this work to investigate, not only the decisions themselves, but also metacognitive judgments (i.e., confidence in the accuracy of the choice set). In two face recognition experiments, we tested the impact of decision strategy (Experiment 1) and confidence judgment strategy (Experiment 2) on the confidence–accuracy relationship. In Experiment 1, participants completed two blocks of recognition trials, one under inclusion (marking previously seen faces) and one under elimination (marking previously unseen faces) instructions. We observed superior resolution (i.e., discrimination between correct and incorrect) for inclusion trials, but only when they were completed prior to use of the elimination strategy. In Experiment 2, all participants completed face recognition trials under inclusion instructions, but we manipulated the strategy used to assess confidence. Again, we observed a significant impact of strategy on confidence–accuracy resolution. Thus, we observed that both the strategy employed to reach a decision and that employed to assess confidence affected the confidence–accuracy relationship. We discuss theoretical and applied (particularly for eyewitness identification and multiple‐choice testing) implications. Copyright © 2012 John Wiley & Sons, Ltd.     

Verbal Memory Deficits in Children with Less than 750 g Birth Weight

Numerous studies have documented memory deficits in very low birthweight (VLBW, &lt; 1500 g) children, yet we know little about the nature of these memory problems. To clarify memory sequelae and examine memory deficits in relation to the degree of low birth weight, we administered the California Verbal Learning Test–Children’s Version (CVLT-C) to a regional sample of 57 &lt; 750 g birthweight children and to groups of 53 750–1499 g birthweight children and 49 term-born controls. Group comparisons revealed significant differences between the &lt; 750 g birthweight group and term-born children on measures of list learning, delayed recall, and inaccurate recall. In addition, the percentage improvement in correct recognitions relative to long-term delayed recall was greater in the &lt; 750 g group than in the term-born controls. Similar differences were observed between VLBW children with and without abnormal neonatal cerebral ultrasounds (high- and low-risk groups). Differences in learning rate between the VLBW and term-born groups, and between high- and low-risk VLBW children, were evident even when vocabulary skill was covaried or when children with neurosensory deficits or IQ &lt; 80 were excluded from analysis. The findings document deficits in verbal memory in the subset of VLBW children at greatest biological risk, and suggest that acquisition processes are selectively impaired.     

对信息源的正向跟随倾向对决策效果的影响*

采用实验研究的方法,检验了二元选择情形下高准确率信息源(准确率x >50%)和低准确率信息源(准确率为1?x)对决策者预测效果的影响。尽管从逻辑上二者从准确率层面具有完全相等的信息价值,然而研究结果显示,决策者更倾向于采用正向跟随而非逆向跟随的方式处理来自信息源的信息。这导致低准确信息源的价值未能得以充分利用。学习和信息源的规范性对该信息处理倾向起到调节作用。     

Temperature-dependent crack surface tension

The fracture surface energy is calculated for a one-dimensional, exactly solvable model of a crack. The temperature dependence of the crack surface tension is determined on the basis of a self-consistent Einstein approach. It is found that lattice vibrations result in a strong reduction in the crack surface tension.