Numerous studies have looked at cognitive processing, more specifically attention, and its important role in various dynamic and static movements. Research on attentional demands in sport is an expanding area with studies now being done on athletes revealing the role of cognitive factors in the execution of motor movements in sports. Objective: the purpose of this study was to determine the attentional demands of a delivery in curling using a classic probe technique with a verbal response time and by measuring numerous performance variables. Subjects: ten healthy skilled curling players and nine healthy novice curling players undertook an auditory probe reaction time concurrently with a delivery in curling. Method: Sixty shots were executed with ten shots for each of the three phases of the shot, in all 30 take outs and 30 draws were done by each participant. The first phase when the player comes out of the “hack”, the second phase of the throw was when the player slid across the “t-line”. The third phase is when the player arrives near the line of Hog and releases the stone. Results: results revealed that reaction times were longer at phase 1 of the delivery for all subjects. The attentional demands for the draw and take out were highest at the phase one of the delivery, furthermore, compared to the draw, a significant rise of RT was seen in phase 3 of the take out shot. Significant differences were also found between the two experimental groups, with the most notable ones being that expert had a better shot success and a slower delivery time than the novice group. Conclusion: These results will lead to a better understanding of the attentional demands of two key shots in the sport of Curling and help curling coaches and teachers, as well as the players of the sport to know more about the attentional demands of the execution movement of the sport. This study also opens a new and interesting perspective on the importance of attention while performing motor tasks that are more complex and demanding.

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No / PURPOSE. This study examined the influence of stimulus chromaticity on simple reaction times (RTs) to determine the stage of chromatic processing that is most influential in their generation. METHODS. Simple RTs were measured in response to the cosinusoidally ramped onset of small, equiluminant, colored Gaussian spots. The chromaticity of these stimuli was varied, to modulate along a series of vectors in color space that included red-green (L-M) and blue-yellow (S-[L+M]) opponent axes. RESULTS. RTs are highly sensitive to small departures from subjective equiluminance. They are also dependent on stimulus chromaticity. The longest RTs are generated in response to equiluminant stimuli that isolate S-cone activity, whereas the shortest are generated by stimuli that modulate the L-M opponent axis. However, temporal processing differences are highly dependent on how the chromatic stimuli are scaled in relation to one another. The differences are reduced when scaling is based on detection threshold. The relationship between chromatic contrast and RT can be described by the modified Piéron equation RT = RT0 + k · C-1. CONCLUSIONS. Simple RTs generated in this study conform to the idea that they are largely determined by cone-opponency mechanisms. The use of cone contrast as a metric for scaling chromatic stimuli exaggerates differences between the temporal responsiveness of L-M and S-(L+M) opponency mechanisms.

Strobe lights have been used successfully in many transportation applications to increase conspicuity. It was hoped that a strobe signal could also be applied to more effectively warn distracted drivers of an unexpected rear end conflict. This "proof of concept study" used a 2 x 2 between-subjects design using thirty-three subjects (16 subjects in the strobe condition, 17 subjects in the no strobe condition) who were divided into two age groups: younger (25-35) and older (60-70). The driver unexpectedly encountered a stopped "surrogate" vehicle in the roadway (with or without a rear-facing strobe light) in a controlled on-road study at the Smart Road located at the Virginia Tech Transportation Institute (VTTI). Results suggested that younger subjects' perception times improved as a result of being exposed to the strobe signal. Faster perception of the situation allowed more time to initiate a brake response. Older subjects perception and response times remained unchanged by the strobe signal. More severe initial steering rate and subjective responses indicated that the strobe conveyed a sense of urgency irrespective of age. Visual distraction of subjects proved difficult. Hence, the impact of the strobe on attracting the attention of a visually distracted driver to the stimulus could not be as fully investigated as originally hoped. The formulation of a more difficult distraction task was suggested for future research to truly assess the ability of the strobe light at alerting visually distracted drivers. / Master of Science

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Possible connection between latent toxoplasmosis and schizophrenia is a very interesting and medically important topic. In this thesis I tried to map current state of knowledge in the interdisciplinary research of schizophrenia and Toxoplasma gondii and their possible connections as well as to show differences in responses between Toxoplasma-positive and Toxoplasma-negative subjects using simple computer-administered tests of prepulse inhibition of startle reaction (PPI). Such differences would suggest another similarity between schizophrenia patients and subjects with latent toxoplasmosis as the sensorimotor gating responsible for PPI was found to be disrupted in schizophrenia patients. Side goal of the study was to test newly developed PC software for testing PPI and to determine its applicability in further research. Subjects for the tests were recruited among adepts of professional military service; 409 subjects completed the test of acoustic PPI and 276 subjects completed the test of visual PPI. All the subjects were tested on presence of specific anti-Toxoplasma IgG in their blood serum. Both tests revealed significant (p<0.001) differences between responses on prepulse-preceded stimuli and plain stimuli without prepulse, no significant results were, however, gained for the effects of latent...

Effects of Toxoplasmosis on Reaction Times and Prepulse Inhibition of Startle Reaction in Humans vi Abstract Toxoplasma gondii, a single-cell coccidia from almost exclusively parasitic phylum Apicomplexa, does not typically cause acute health issues in humans with most exceptions among immunodeficient individuals and pregnant mothers or, more precisely, their offspring. In the latent phase, the bradyzoites in tissue cysts placed most often in neural and muscle tissues can evolve pressure on the host's body both as a collateral effect of the presence of the parasitic organism in host's tissues and as a consequence of adaptive evolution leading to increase in probability of trophic transmission to the final host, a felid. In humans, this can result in slight changes in personality profiles, deterioration of psychomotor and cognitive functions, and development of serious mental disorders. The thesis focuses predominantly on one of the aspects of the changes, namely the effect of latent toxoplasmosis on the processing of startle signals themselves and when modified by a preceding low-intensity signal; this processing may be connected with the development of schizophrenia in predisposed individuals. Studies conducted within the project framework found changes int the speed of signal processing in...

The Stroop effect is the delay in reaction times due to interference. Since the original experiments of 1935, it has been used primarily in linguistic context. Language is a complex skill unique to humans, which involves a large part of the cerebral cortex and many subcortical regions. It is perceived primarily in auditory form (spoken) and secondarily in visual form (written), but it is also always perceived in representational form (natural sounds, images, smells, etc). Auditory signals are processed much faster than visual signals, and the language processing centres are closer to the primary auditory cortex than the primary visual cortex, but due to the integration of stimuli and the role of the executive functions, we are able to perceive both simultaneously and coherently. However, auditory signals are still processed faster, and this study focused on establishing how auditory and visual, linguistic and representational stimuli interact with each other and affect reaction times in four Stroop tasks with four archetypal mammals (dog, cat, mouse and pig): a written word against an image, a spoken word against an image, a written word against a natural sound and a spoken word against a natural sound. Four hypotheses were tested: in all tasks reaction times would be faster when the stimuli were congruent (Stroop Hypothesis); reaction times would be faster when both stimuli are auditory than when they are visual (Audiovisual Hypothesis); reaction times would be similar in the tasks where one stimulus is auditory and the other visual (Similarity Hypothesis); finally, reaction times would be slower when stimuli come from two sources than when they come from one source (Attention Hypothesis). Twelve native speakers of Swedish between the ages of 22 and 40 participated. The experiment took place in the EEG lab of the Linguistics Department of Stockholm University. The same researcher (the author) and equipment was used for all participants. The results confirmed the Stroop Hypothesis, did not confirm the Audiovisual and Similarity Hypothesis, and the results of the Attention Hypothesis were mixed. The somewhat controversial results were mostly attributed to a false initial assumption, namely that having two different auditory stimuli (one on each ear) was considered one source of stimuli, and possibly the poor quality of some natural sounds. With this additional consideration, the results seemed to be in accord with previous research. Future research could focus on more efficient ways to test the reaction times of Stroop tasks involving auditory and visual stimuli, as well as different populations, especially neurodiverse and bilingual populations.

Il lavoro di tesi si è focalizzato sullo studio dell’arousal come indice psicofisiologico di attivazione e sull’applicazione della metodica di stimolazione elettrica transcranica (tES) non invasiva con lo scopo di modulare tale indice. L’obiettivo è stato quello di indagare se, applicando la tES, fosse possibile migliorare la performance di soggetti giovani sani in compiti di tipo cognitivo. Il progetto di ricerca si è sviluppato in 2 studi principali per un totale di 4 esperimenti. Tali studi hanno previsto l’acquisizione e la successiva analisi sia di dati comportamentali (tempi di reazione, accuratezza), che di indici psicofisiologici (conduttanza cutanea, diametro pupillare). I risultati hanno evidenziato che è possibile modulare l’arousal con dei “bursts” di stimolazione elettrica transcranica, somministrati in concomitanza di stimoli salienti per il soggetto. Tale modulazione si è manifestata con una riduzione dei tempi di reazione ed un contemporaneo aumento della risposta di conduttanza cutanea. Questi dati supportano la possibilità di utilizzare questo protocollo in pazienti con difficoltà di attenzione o altri problemi cognitivi per aumentare l’efficacia di interventi di riabilitazione. / The thesis analyzed the role of the arousal as a psychophysiological index of activation, and the application of non-invasive transcranial electrical stimulation (tES) technique with the aim to modulate this index. In this work we investigated if the application of tES could increase the performance of healthy young subjects during cognitive tasks. The thesis is based on 2 main studies for a total of 4 experiments with the recording of behavioural (reaction times, accuracy) and psychophysiological (skin conductance, pupil diameter) indeces. The results showed that it is possible to modulate arousal with bursts of tES, administered during the presentation of salient stimuli for the subject. This modulation resulted in a reduction of reaction times and an increase of the skin conductance response. These data support the possibility to use this protocol of stimulation with patients with attentional and other cognitive deficits in a rehabilitative context.