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There are consistent correlations between mathematics achievement, attitudes, and anxiety, but the longitudinal relations among these constructs are not well understood nor are sex differences in these relations. To address this gap, mathematics achievement, attitudes, and anxiety were longitudinally assessed for 342 (169 boys) adolescents from seventh to ninth grade, inclusive, and latent growth curve models (LGCM) were used to assess the relations among these traits and developmental change in them. Spatial abilities (seventh and eighth grades) and trait anxiety (eighth and ninth grades) were also assessed and used to control for sex differences in these traits. Overall, boys had stronger spatial abilities and more positive mathematics attitudes and were less anxious than girls, but there were no sex differences in mathematics achievement. Across grades, mathematics achievement improved, attitudes became less positive, and anxiety increased for both boys and girls. Higher than average cross-grade growth in mathematics achievement mitigated boys' developmental declines in mathematics attitudes and increases in anxiety. Girls with strong spatial abilities had lower mathematics anxiety, but girls overall maintained higher mathematics anxiety and less positive mathematics attitudes relative to boys, even when they showed strong cross-grade gains in mathematics achievement. The study demonstrated that longitudinal gains in mathematics are associated with cross-grade changes in attitudes and anxiety but with several different developmental patterns for boys and girls.

Assessing the time course under which underlying memory representations can be formed is an important question for understanding memory. Several studies assessing item memory have shown that gist representations of items are laid out more rapidly than verbatim representations. However, for associations among items/components, which form the core of episodic memory, it is unclear whether gist representations form more quickly than, or at least in parallel with, verbatim representations, as fuzzy-trace theory predicts, or whether gist is extracted more slowly from inferring the meaning of verbatim representations, as in gist macroprocessor theories. To test these contrasting possibilities, we used a novel associative recognition task in which participants studied face-scene pairs for 0.75, 1.5, or 4 seconds each, and were later tested on their ability to discriminate intact pairs from foils which varied in how similar they were to originally studied pairs. Across 2 experiments, we found that verbatim memory for associations, measured using a multinomial-processing-tree model, improved from 0.75 to 1.5 to 4 seconds of presentation time. Paralleling these effects of encoding time on verbatim memory, for gist memory, there were improvements from 0.75 seconds to 1.5 seconds in both experiment 1 and 2, while improvements from 1.5 seconds to 4 seconds were only evident when the retention interval between study and test was increased (experiment 2). These results provide strong support for the parallel processing framework of fuzzy-trace theory over the slow gist extraction framework of an alternative gist macroprocessor theory.

In the traditional conception of working memory for word lists, phonological codes are used primarily, and semantic codes are often discarded or ignored. Yet, other evidence indicates an important role for semantic codes. We carried out a preplanned set of four experiments to determine whether phonological and semantic codes are used similarly or differently. In each trial, random lists of one, two, three, four, six, or eight words were followed by a probe to be judged present in the list or absent from it. Sometimes, a probe was absent from the list but rhymed with a list item (in Experiments 1 and 2) or was a synonym of a list item (in Experiments 3 and 4). A probe that was similar to a list item was to be rejected just like other nontarget probes, a reject-similar use (in Experiments 1 and 3), or it was to be placed in the same category as list items, an accept-similar use (in Experiments 2 and 4). The results were comparable in the accept-similar use of both phonological and semantic codes. However, the reject-similar use was interestingly different. Rejecting rhyming items was more difficult than rejecting control words, as expected, whereas rejecting synonyms was easier than rejecting control words, presumably due to a recall-to-reject process. This effect increased with memory load. We discuss theoretically important differences between the use of phonology and semantics in working memory.

Dividing attention (DA) between a memory task and a secondary task results in deficits in memory performance across a wide array of memory tasks, but these effects are larger when DA occurs at encoding than at retrieval. Although some research suggests the effects of DA are equal for item and associative memory, thereby suggesting that DA disrupts all components of an episode to the same extent, there have been relatively few studies directly examining the effects of DA on multiple features of the same episode. In addition, no studies have examined how DA may affect the stochastic dependency between multiple source dimensions of a given episode, which is central to theories of source memory, and episodic memory in general. Thus, in two experiments, we used a multidimensional source memory task--examining memory for items and multiple source features--and separately investigated how DA at encoding or at retrieval affects item memory, source memory, and joint source retrieval. DA was manipulated at encoding in Experiment 1 and at retrieval in Experiment 2. Whereas DA at encoding disrupted item memory, as well as source memory and source-source binding, though to a lesser extent, DA at retrieval did not affect any of these outcomes. Results are discussed in terms of levels of binding and the role of attention in encoding and retrieval of bounded episodic representations.

The relation between an individual's memory accuracy and reported confidence in their memories can indicate self-awareness of memory strengths and weaknesses. We provide a lifespan perspective on this confidence-accuracy relation, based on two previously published experiments with 320 participants, including children aged 6-13, young adults aged 18-27, and older adults aged 65-77, across tests of working memory (WM) and long-term memory (LTM). Participants studied visual items in arrays of varying set sizes and completed item recognition tests featuring 6-point confidence ratings either immediately after studying each array (WM tests) or following a long period of study events (LTM tests). Confidence-accuracy characteristic analyses showed that accuracy improved with increasing confidence for all age groups and in both WM and LTM tests. These findings reflect a universal ability across the lifespan to use awareness of the strengths and limitations of one's memories to adjust reported confidence. Despite this age invariance in the confidence-accuracy relation, however, young children were more prone to high-confidence memory errors than other groups in tests of WM, whereas older adults were more susceptible to high-confidence false alarms in tests of LTM. Thus, although participants of all ages can assess when their memories are weaker or stronger, individuals with generally weaker memories are less adept at this confidence-accuracy calibration. Findings also speak to potential different sources of high-confidence memory errors for young children and older adults, relative to young adults. [ABSTRACT FROM AUTHOR]

A two-axis solar tracker and its interactive kiosk were designed by an interdisciplinary team of students and faculty. The objective was to develop a publicly accessible kiosk that would facilitate the study of energy usage and production on campus. Tracking is accomplished by an open-loop algorithm, microcontroller, and ham radio rotator. Solar panel output is monitored in real time and displayed to the public with lights and digits that can be read by the casual passersby. While maximum power point tracking is the most accurate means of quantifying the output power of a photovoltaic panel, simplicity and design constraints dictated the use of short-circuit current as a proxy for power. A touchscreen display allows kiosk visitors to compare two solar panels, an automatic tracker that faces the sun, and an identical panel whose elevation and azimuth can be controlled with a virtual joystick. This project was a capstone experience for students in physics/engineering, computer science, and instructional technology. We discuss technical challenges and design choices, as well as the educational goals of the kiosk.

Force probes are versatile tools in the physics lab, but their internal workings can introduce artifacts when measuring rapidly changing forces. The Dual-Range Force Sensor by Vernier uses strain gage technology to measure force, based on the bending of a beam. Strain gages along the length of the beam change resistance as the beam bends. The elasticity of the beam leads to oscillations that persist after being excited by an impulsive force. How quickly the force probe freely returns to zero is thus related to the rigidity of the beam and the total mass attached to it. By varying the added mass and measuring the resulting frequency of the probe's internal free oscillations, the effective mass and spring constant of the probe's moveable parts can be found. Weighing of the probe parts and conducting a Hooke's law experiment provide static verification of these parameters. Study of the force sensor's behavior helps students to learn about damped harmonic motion, mathematical modeling, and the limitations of measuring devices.

Students can learn the Bernoulli principle of fluid pressure by looking at the mechanisms that operated the shut-off sensor in the nozzle of a gas pump.

An experiment to find out the energy changes between the plates of capacitor, under different conditions of constant charge and constant voltage are examined by using energy flow diagrams.

The history of the candela, which is one of the seven SI base units, its measurement techniques and its relation to the lumen are discussed. To find out the relationship, the luminous properties of incandescent and fluorescent lamps are compared.

The flow of water in a garden hose can help illustrate Isaac Newton's second law of motion. When both ends of the hose are stationary and water is flowing, moving the hose in the direction of the flow decreases flow rate, while moving the hose against the flow increases the flow rate. Scientific analysis of this phenomenon illustrates important physics principles.

The manner in which several light bulbs light up in a series circuit are examined, focusing on how lights burn at different brightness and illuminate at different times. Topics include the nature of a non-ohmic conductor and power dissipation within different resistors.