Exploring the effect of subliminal single-word and multiple-word primes on working memory performance

This PhD thesis focused on subliminal priming, that is, the presentation of information below conscious awareness (Vernon, 2009), which has been shown to influence both cognitive and affective behaviours. Information can be presented subliminally using both ‘Single-Word’ and ‘Multiple-Word’ written primes, although the two prime types have not yet been compared. Currently there is no reported optimal procedure for the presentation of subliminal stimuli, thus such a comparison could guide future research concerning prime choice. Hence, this thesis empirically compared the effects produced by Single-Word and Multiple-Word primes in a series of experiments. In Experiment 1 96 participants were subliminally stimulated with one of six alternative primes, three Single-Word primes (cognitive: intelligent; affective: one; neutral-control: walking), and three Multiple-Word primes (cognitive: I am intelligent; affective: mommy and I are one; neutral-control: people are walking), and their performance measured on a range of cognitive (e.g., working memory, intelligence, selective attention) andaffective (e.g., mood and state anxiety) tasks. Results of Experiment 1 showed no clear change in participants’ intelligence, selective attention, mood, or state anxiety. However, post hoc analysis found participants’ significantly improved their working memory performance following exposure to all positive (e.g., cognitive and affective) subliminal primes, regardless of prime type (i.e., Single-Word and Multiple-Word). Experiment 2 followed this up by exploring the effect of subliminal priming on working memory performance. Sixty participants were primed with one of the six subliminal stimuli to assess whether the non-differential effect between prime types found in Experiment 1 was due to the varied length of time between the end of subliminal exposure and the onset of the task. Results found all participants’ performance improved regardless of prime type and prime content and thus was concluded to reflect a practice effect. Experiment 3 considered that the absence of any subliminal priming may have been due to participants’ potential lack of motivation to attain the goal of improving working memory. Hence, 106 participants were primed with one of the six subliminal stimuli and their motivation to achieve this goal was enhanced using falsepositive feedback on performance and reading a false article extract highlighting the benefit of a good working memory. Results found, despite increased motivation to improve working memory, that subliminal priming did not have any effect on performance. Experiment 4 considered whether the specific content of the subliminal stimuli, the short prime-target stimulus onset asynchrony (SOA), or the type of task could be accountable for the null results. Thus, in addition to enhancing participant motivation, the content of the stimuli were refined to become more task-relevant, the prime-target SOA was extended from 14ms to 514ms to allow more time for unconscious processing. Eighty-three participants were primed with one of four subliminal stimuli; two Single-Word primes (memory-specific: remember; neutralcontrol: walking) and two Multiple-Word primes (memory-specific: I can remember well; neutral-control: people are walking), and performance was measured using two working memory tasks. Results found all participants’ performance improved on both working memory tasks regardless of prime type and prime content and was concluded to reflect a practice effect. Finally, a meta-analysis conducted on the data from the Conceptual Span Task from all four experiments confirmed an improvement on performance over time but no evidence of any subliminal priming effects. Overall, this thesis found it was not possible to establish a difference between the two prime types, although findings indicate that subliminal priming may not be able to improve performance of the phonological loop component of working memory

X-ray spectral complexity in narrow-line Seyfert 1 galaxies

We present a systematic analysis of the X-ray spectral properties of a sample of 22 ``narrow-line'' Seyfert 1 galaxies for which data are available from the ASCA public archive. Many of these sources, which were selected on the basis of their relatively narrow H-beta line width (FWHM <= 2000 km/s), show significant spectral complexity in the X-ray band. Their measured hard power-law continua have photon indices spanning the range 1.6 - 2.5 with a mean of 2.1, which is only slightly steeper than the norm for ``broad-line'' Seyfert 1s. All but four of the sources exhibit a soft excess, which can be modelled as blackbody emission (T_{bb} ~ 100 - 300 eV) superposed on the underlying power-law. This soft component is often so strong that, even in the relatively hard bandpass of ASCA, it contains a significant fraction, if not the bulk, of the X-ray luminosity, apparently ruling out models in which the soft excess is produced entirely through reprocessing of the hard continuum. Most notably, 6 of the 22 objects show evidence for a broad absorption feature centred in the energy range 1.1 - 1.4 keV, which could be the signature of resonance absorption in highly ionized material. A further 3 sources exhibit ``warm absorption'' edges in the 0.7 - 0.9 keV bandpass. Remarkably, all 9 ``absorbed'' sources have H-beta line widths below 1000 km/s, which is less than the median value for the sample taken as a whole. This tendency for very narrow line widths to correlate with the presence of ionized absorption features in the soft X-ray spectra of NLS1s, if confirmed in larger samples, may provide a further clue in the puzzle of active galactic nuclei.Comment: 13 pages, 5 figures, accepted for publication in MNRA

Transient Relativistically-Shifted Lines as a Probe of Black Hole Systems

X-ray spectra of Seyfert galaxies have revealed a new type of X-ray spectral feature, one which appears to offer important new insight into the black hole system. XMM/Chandra revealed several narrow emission lines redward of Fe Kalpha in NGC 3516. Since that discovery the phenomenon has been observed in other Seyfert galaxies, e.g. NGC 7314 and ESO 198-G24. We present new evidence for a redshifted Fe line in XMM spectra of Mrk 766. These data reveal the first evidence for a significant shift in the energy of such a line, occurring over a few tens of kiloseconds. This shift may be interpreted as deceleration of an ejected blob of gas traveling close to the escape velocity.Comment: 13 pages, 5 figures (4 color) accepted by Ap

Probing the cool ISM in galaxies via 21cm HI absorption

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm absorption profiles often show two distinct spectral-line components: narrow, deep lines arising from cold gas in the extended disc of the galaxy, and broad, shallow lines from cold gas close to the AGN (e.g. Morganti et al. 2011). Here, we present results from a targeted search for associated HI absorption in the youngest and most recently-triggered radio AGN in the local universe (Allison et al. 2012b). So far, by using the recently commissioned Australia Telescope Compact Array Broadband Backend (CABB; Wilson et al. 2011), we have detected two new absorbers and one previously-known system. While two of these show both a broad, shallow component and a narrow, deep component (see Fig. 1), one of the new detections has only a single broad, shallow component. Interestingly, the host galaxies of the first two detections are classified as gas-rich spirals, while the latter is an early-type galaxy. These detections were obtained using a spectral-line finding method, based on Bayesian inference, developed for future large-scale absorption surveys (Allison et al. 2012a).Comment: 1 page, 1 figure, published in Proceedings of IAU Symposium No. 29

Why we need interprofessional education to improve the delivery of safe and effective care

Interprofessional education (IPE) is an activity that involves two or more professions who learn interactively together to improve collaboration and the quality of care. Research has continually revealed that health and social care professionals encounter a range of problems with interprofessional coordination and collaboration which impact on the quality and safety of care. This empirical work resulted in policymakers across health care education and practice to invest in IPE to help resolve this collaborative failures. It is anticipated that IPE will provide health and social care professionals with the abilities required to work together effectively in providing safe high quality care to patients. Through a discussion of a range of key professional, educational and organization issues related to IPE, this paper argues that this form of education is an important strategy to improve the delivery of safe and effective care

The Variable X-ray Spectrum of Markarian 766 - II. Time-Resolved Spectroscopy

CONTEXT: The variable X-ray spectra of AGN systematically show steep power-law high states and hard-spectrum low states. The hard low state has previously been found to be a component with only weak variability. The origin of this component and the relative importance of effects such as absorption and relativistic blurring are currently not clear. AIMS: In a follow-up of previous principal components analysis, we aim to determine the relative importance of scattering and absorption effects on the time-varying X-ray spectrum of the narrow-line Seyfert 1 galaxy Mrk~766. METHODS: Time-resolved spectroscopy, slicing XMM and Suzaku data down to 25 ks elements, is used to investigate whether absorption or scattering components dominate the spectral variations in Mrk 766.Time-resolved spectroscopy confirms that spectral variability in Mrk 766 can be explained by either of two interpretations of principal components analysis. Detailed investigation confirm rapid changes in the relative strengths of scattered and direct emission or rapid changes in absorber covering fraction provide good explanations of most of the spectral variability. However, a strong correlation between the 6.97 keV absorption line and the primary continuum together with rapid opacity changes show that variations in a complex and multi-layered absorber, most likely a disk wind, are the dominant source of spectral variability in Mrk 76