Mark A. Stellmack

An Assessment of Reliability and Validity of a Rubric for Grading APA-Style Introductions

This article describes the empirical evaluation of the reliability and validity of a grading rubric for grading APA-style introductions of undergraduate students. Levels of interrater agreement and intrarater agreement were not extremely high but were similar to values reported in the literature for comparably structured rubrics. Rank-order correlations between graders who used the rubric and an experienced instructor who ranked the papers separately and holistically provided evidence for the rubrics validity. Although this rubric has utility as an instructional tool, the data underscore the seemingly unavoidable subjectivity inherent in grading student writing. Instructors are cautioned that merely using an explicit, carefully developed rubric does not guarantee high reliability.

Observer weighting of interaural delays in source and echo clicks

A correlational analysis was used to assess the relative weight given to the interaural differences of time (IDTs) of source and echo clicks for echo delays ranging from 1-256 ms. In three different experimental conditions, listeners were instructed to discriminate the IDT of the source, the IDT of the echo, or the difference between the IDTs of the source and echo. The IDT of the target click was chosen randomly and independently from trial-to-trial from a Gaussian distribution (mu = 0 microsecond, sigma = 100 microseconds). The IDT of the nontarget click was either fixed at 0 microsecond or varied in the same manner as the IDT of the target. The data show that for echo delays of 8 ms or less, greater weight was given to the IDT of the source than to that of the echo in all experimental conditions. For echo delays from 16-64 ms, the IDT of the echo was weighted slightly more than that of the source and the weights accounted for a greater proportion of the responses when the echo was the target, indicating that the binaural information in the echo was dominant over the binaural information in the source. The data suggested the possibility that for echo delays from 8-32 ms, listeners were unable to resolve the temporal order of the source and echo IDTs. Listeners were able to weight the binaural information in the source and echo appropriately for a given task only when the echo delay was 128 ms or greater.

Review, Revise, and Resubmit The Effects of Self-Critique, Peer Review, and Instructor Feedback on Student Writing

These experiments examined the common practice of allowing students to revise and resubmit papers after receiving feedback. Blind graders evaluated students’ first and second drafts of an introduction in American Psychological Association (APA) format. Across experiments, just over 50% of students’ scores improved across drafts when evaluated by blind graders compared to over 80% improvement for the scores assigned by the graduate student lab instructors. In examining the effects of the source of feedback on first drafts, no difference between self-critique, peer review, and feedback from the lab instructor was found in blind graders’ scores. The results suggest that high scores obtained through the review–revise–resubmit procedure do not reflect good writing in an objective sense, but rather an ability to satisfy a particular reviewer.

Monaural and interaural temporal modulation transfer functions measured with 5-kHz carriers

Temporal modulation transfer functions (TMTFs) were measured for detection of monaural sinusoidal amplitude modulation and dynamically varying interaural level differences for a single set of listeners. For the interaural TMTFs, thresholds are the modulation depths at which listeners can just discriminate interaural envelope-phase differences of 0 and 180 degrees. A 5-kHz pure tone and narrowband noises, 30- and 300-Hz wide centered at 5 kHz, were used as carriers. In the interaural conditions, the noise carriers were either diotic or interaurally uncorrelated. The interaural TMTFs with tonal and diotic noise carriers exhibited a low-pass characteristic but the cutoff frequencies changed nonmonotonically with increasing bandwidth. The interaural TMTFs for the tonal carrier began rolling off approximately a half-octave lower than the tonal monaural TMTF (approximately 80 Hz vs approximately 120 Hz). Monaural TMTFs obtained with noise carriers showed effects attributable to masking of the signal modulation by intrinsic fluctuations of the carrier. In the interaural task with dichotic noise carriers, similar masking due to the interaural carrier fluctuations was observed. Although the mechanisms responsible for differences between the monaural and interaural TMTFs are unknown, the lower binaural TMTF cutoff frequency suggests that binaural processing exhibits greater temporal limitation than monaural processing.

The reduction of binaural interference by the temporal nonoverlap of components

Threshold interaural delays were measured for a single interaurally delayed 753-Hz target component presented against a background of six diotic distractor components (453, 553, 653, 853, 953, and 1053 Hz). In one set of conditions, all components were gated on simultaneously, but 200-ms after their onset the distractors were turned off for 10, 25, 50, 100, or 200 ms, then turned on again for the remainder of the 500-ms listening interval. In a second set of conditions, the target component was present only during the temporal notch in the distractors for notch durations of 50, 100, and 200 ms. Threshold interaural delays were also measured for the target component in isolation at durations of 50, 100, 200, and 500 ms. In both sets of conditions in which the distractors were present, it was observed that a brief isolated presentation of the target reduced threshold interaural differences of time to nearly the level of thresholds for the target presented in total isolation, while thresholds were many times higher when the distractors had no temporal notch. Possible sources of binaural interference are discussed and the evidence supporting each is evaluated.

Comparison of Honor Code and Non-Honor Code Classrooms at a Non-Honor Code University

The present paper examines the effects of a classroom honor code at a non-honor code institution by comparing a class with an honor code (HC) to a non-honor code (NHC) class. The HC class had a peer-reporting requirement and unproctored quizzes and exams. The NHC class used traditional methods of enforcing academic honesty. Surveys were distributed to the students in both classes asking for self-reports of cheating and beliefs about the instructors’ attitudes toward academic dishonesty. Despite the increased ease and temptation of engaging in academic dishonesty in the HC classroom, results showed that there was no difference in number of students who reported cheating or in number of students who witnessed cheating in the two classes. A greater proportion of students in the HC classroom than in the NHC classroom perceived the instructor to be trusting and respecting of students, and to hold academic integrity as more important than other instructors. These results suggest a classroom honor code may be a viable mechanism for promoting academic integrity through improvement of the student-instructor relationship.

The effect of distractor frequency on judgments of target laterality based on interaural delays

A two-dimensional stimulus-classification paradigm was used to examine the ability of listeners to judge the laterality of an interaurally delayed low-frequency target component presented concurrently with a distractor component. Of primary interest was the effect on performance of the frequency difference (Delta f) between the target and distractor. In one set of conditions, the target was fixed at 753 Hz and the distractor was 353, 553, 653, 703, 803, 853, 953, or 1153 Hz (fixed within a block of trails). In a second set of conditions, the distractor was fixed at 753 Hz and the target frequency was 353, 553, 653, 703, 803, 953, or 1153 Hz. The listeners were presented with a target component with an interaural delay that varied from trial to trial, taking on one of ten values, five leading to the left ear and five leading to the right. A distractor component was simultaneously presented with an interaural delay that also took on one of the same ten values. Delays ranged from -90 to (+)90 microseconds in 20-microsecond steps. during a block of 100 trials, each of the possible combinations of target and distractor delay was presented once and only once in a random order. Listeners were instructed to make left-right judgments based on the target delay. Each condition was repeated ten times, and the slopes of the best linear boundaries between left and right responses were used to derive the relative weights given to the target and distractor. The duration of the signals was 200 microseconds. Two of the eight listeners weighted the target heavily when the target and distractor were spectrally remote but gave the two components equal weight when the different in frequency was small. These two listeners yielded similar target weights regardless of which component was designated as the target. One listener gave nearly equal weight to the target and the distractor regardless of Delta f. Five of the listeners gave greater weight to the higher of the two frequencies regardless of which was assigned as the target. This high-frequency dominance is explained in terms of cross-correlation functions based on the composite two-tone waveforms.

Discrimination of interaural phase differences in the envelopes of sinusoidally amplitude-modulated 4-kHz tones as a function of modulation depth

Psychometric functions were measured for the discrimination of the interaural phase difference (IPD) of the envelope of a sinusoidally amplitude-modulated (SAM) 4-kHz pure tone for modulation frequencies of 128 and 300 Hz and modulation depths (m) of 0.2, 0.6, 0.9, and 1.0. Contrary to recent modeling assumptions, it was found that a constant change in normalized interaural envelope correlation, with or without additional model stages to simulate peripheral auditory processing, did not produce a constant level of performance. Rather, in some cases, performance could range from chance to near perfect across modulation depths for a given change in normalized interaural envelope correlation. This was also true for the maximum change in normalized interaural envelope correlation computed across the cross-correlation functions for the stimuli to be discriminated. The change in the interaural time difference (ITD) computed from the IPD accounted for discriminability across modulation depths better than the change in normalized interaural envelope correlation, although ITD could not account for all the data, particularly those for lower values of m.

Extracting binaural information from simultaneous targets and distractors: Effects of amplitude modulation and asynchronous envelopes

When different components of a stimulus carry different binaural information, processing of binaural information in a target component is often affected. The present experiments examine whether such interference is affected by amplitude modulation and the relative phase of modulation of the target and distractors. In all experiments, listeners attempted to discriminate interaural time differences of a target stimulus in the presence of distractor stimuli with ITD=0. In Experiment 1, modulation of the distractors but not the target reduced interference between components. In Experiment 2, synthesized musical notes exhibited little binaural interference when there were slight asynchronies between different streams of notes (31 or 62 ms). The remaining experiments suggested that the reduction in binaural interference in the previous experiments was due neither to the complex spectra of the synthesized notes nor to greater detectability of the target in the presence of modulated distractors. These data suggest that this interference is reduced when components are modulated in ways that result in the target appearing briefly in isolation, not because of segregation cues. These data also suggest that modulation and asynchronies between modulators that might be encountered in real-world listening situations are adequate to reduce binaural interference to inconsequential levels.

Discrimination of depth of sinusoidal amplitude modulation with and without roved carrier levels

Thresholds for the discrimination of the depth of sinusoidal amplitude modulation with a broadband noise carrier were measured for three listeners in a two-alternative, forced-choice task for modulation frequencies of 8, 32, and 128 Hz. Thresholds were measured with the spectrum level of the carrier fixed at 20 dB across all trials and, separately, with the carrier spectrum level roved randomly over a 20-dB range (10-30 dB) in each interval. Mean thresholds were equal or slightly lower (but not significantly so) for the fixed conditions relative to the roved conditions, and the differences between thresholds were too small to be explained by assuming that listeners compared instantaneous intensity at corresponding phases of the modulation cycle (for example, in the troughs). Rather, it appears that listeners discriminated modulation depth by extracting an estimate of the modulation depth within each interval that was independent of the overall level. Consequently, models of envelope extraction must include normalization of the envelope fluctuations to the envelope dc.