Assessing Omitted Confounder Bias in Multilevel Mediation Models

To draw valid inference about an indirect effect in a mediation model, there must be no omitted confounders. No omitted confounders means that there are no common causes of hypothesized causal relationships. When the no-omitted-confounder assumption is violated, inference about indirect effects can be severely biased and the results potentially misleading. Despite the increasing attention to address confounder bias in single-level mediation, this topic has received little attention in the growing area of multilevel mediation analysis. A formidable challenge is that the no-omitted-confounder assumption is untestable. To address this challenge, we first analytically examined the biasing effects of potential violations of this critical assumption in a two-level mediation model with random intercepts and slopes, in which all the variables are measured at Level 1. Our analytic results show that omitting a Level 1 confounder can yield misleading results about key quantities of interest, such as Level 1 and Level 2 indirect effects. Second, we proposed a sensitivity analysis technique to assess the extent to which potential violation of the no-omitted-confounder assumption might invalidate or alter the conclusions about the indirect effects observed. We illustrated the methods using an empirical study and provided computer code so that researchers can implement the methods discussed.     

Reflective writing: I wouldn’t start from here – examining a professional development initiative to enhance the scholarly activity of English HE in FE lecturers

This paper explores the nature of reflective writing through the experience of the researchers in running a series of writing workshops with a group of higher education practitioners working in a UK further education college. The focus here is on reflective writing, which was chosen to start the sequence of workshops, as it was perceived as a form of writing with which the participants would be familiar, given its role in the education and development of teachers within the sector. Our assumption was that this familiarity would facilitate the writing process and participants would readily respond by engaging in reflective writing. However, in practice this proved not to be the case, despite being introduced to a variety of different forms of writing over a series of workshops, it took the participants longer than we expected to begin to write. This led us to question our assumptions about the starting point for the writing workshops and what they might achieve. The paper draws on field notes made during the writing initiative and data gathered through focus groups and interviews with the participants, as well as extracts of their writing to examine their experiences. Different conceptualisations of reflective writing are identified and their implications are explored in relation to the participants’ engagement with writing and their experience of professional development.     

Teaching and learning the esoteric: an insight into how reflection may be internalised with reference to the occupational therapy profession

This paper is concerned with the ways in which reflective practice is learnt, taught and assessed within the profession of occupational therapy. It utilises individual experiences of reflection of both students and staff members in university and practice placement settings. The discussion places reflection within learning a profession’s way of being and individual learner’s relation to this ‘sense of being’. It concludes that the ‘rote’ way in which reflection is currently used to demonstrate evidence of reflective practice is detrimental to the development of a reflective professional, in this instance, an occupational therapist.     

When Trust Fails: The Relation Between Children’s Trust Beliefs in Peers and their Peer Interactions in a Natural Setting

One hundred and forty-nine 8–11 year-old children (86 males; M?=?9 years - 4 months and SD?=?7 months) from the UK were administered the Trust Beliefs in Peers scale and were observed in the playground over one school year. Quadratic relations were found between trust beliefs in peers and peer interaction, which varied by gender. Compared to girls with the middle range of trust beliefs, girls with very low beliefs and those with very high beliefs (a) were less accepted/more rejected by the peer group (i.e., lower group interaction, and greater negatively received bids), (b) showed greater indirect aggression (engaged in and received), (c) showed greater non-engagement (i.e., being alone), and (d) showed greater concomitant distress. Compared to children with the middle range of trust beliefs, children with those extreme trust beliefs in peers demonstrated greater direct aggression (engaged in and received) and showed passive behavior (for boys only). The findings supported the conclusion that children, primarily girls, who trust peers too little and those who trust too much are at risk for psychosocial maladjustment.     

Retroactive semantic priming in a lexical decision task

The present study reports two experiments that required subjects to name target items preceded by a masked prime. Additionally, and subsequent to the naming task, subjects were required to indicate whether or not the prime was a word, along with a confidence rating of their lexical decision. Experiment 1 demonstrates that the processing of masked primes is facilitated by related targets when such targets are presented either 100 or 200 msec after the onset of the prime. Experiment 2 extends the finding of “retroactive” priming to a 1000=msec separation in prime-target presentation (SOA). The extent of retroactive priming is not dependent on SOA between prime and target, nor is it affected by the prime-mask SOA, which varied from 10 to 180 msec. Priming of targets was also independent of prime-target and prime-mask SOA, providing that primes had been classified as words. For word primes classified as non-words there was no semantic priming on target naming reaction time. Implications of these findings with respect to the nature of retroactive priming and the current controversy concerning subliminal priming effects were discussed.     

Single band amplitude envelope cues as an aid to speechreading

Amplitude envelopes derived from speech have been shown to facilitate speech-reading to varying degrees, depending on how the envelope signals were extracted and presented and on the amount of training given to the subjects. In this study, three parameters related to envelope extraction and presentation were examined using both easy and difficult sentence materials: (1) the bandwidth and centre frequency of the filtered speech signal used to obtain the envelope; (2) the bandwidth of the envelope signal determined by the lowpass filter cutoff frequency used to “smooth” the envelope fluctuations; and (3) the carrier signal used to convey the envelope cues. Results for normal hearing subjects following a brief visual and auditory-visual familiarization/training period showed that (1) the envelope derived from wideband speech does not provide the greatest benefit to speechreading when compared to envelopes derived from selected octave bands of speech; (2) as the bandwidth centred around the carrier frequency increased from 12.5 to 1600 Hz, auditory-visual (AV) performance obtained with difficult sentence materials improved, especially for envelopes derived from high-frequency speech energy; (3) envelope bandwidths below 25 Hz resulted in AV scores that were sometimes equal to or worse than speechreading alone; (4) for each filtering condition tested, there was at least one bandwidth and carrier condition that produced AV scores that were significantly greater than speech-reading alone; (5) low-frequency carriers were better than high-frequency or wideband carriers for envelopes derived from an octave band of speech centred at 500 Hz; and (6) low-frequency carriers were worse than high-frequency or wideband carriers for envelopes derived from an octave band centred at 3150 Hz. These results suggest that amplitude envelope cues can provide a substantial benefit to speechreading for both easy and difficult sentence materials, but that frequency transposition of these signals to regions remote from their “natural” spectral locations may result in reduced performance.