The Effectiveness of Visual vs. Auditory Presentation of Information on Memory

This research project aimed to determine whether it was easier for individuals to memorize and recall words when being presented with a visual presentation than with an auditory presentation. Method: To gather data, an online survey was designed and conducted to test participants more sufficiently. This study consisted of individuals that were 18 years or older and who have good visual and auditory abilities. This study was conducted using two lists of 10 words that contained six letters, three syllables, and were nouns. Half of my participants were presented with 10 words visually whereas the other half of the participants were shown the 10 words auditorily. Specifically, half of the participants received List A either visually or auditorily while the other half received List B either visually or auditorily. Each participant only received one list of words during the trial, presented in different ways. After collecting the data, the difference between the two groups of subjects and the number of words correctly recalled were compared using an independent samples t-test. Results: The analysis then revealed which presentation, visual or auditory, was easier to memorize and recall. Discussion: Thus, I hypothesized that it would be more challenging to memorize and recall a list of words when presented auditorily than visually

A magnocellular contribution to conscious perception via temporal object segmentation

The human visual system is continuously confronted with dynamic visual input. One challenge that the visual system must solve, therefore, is recognizing when two distinct objects have appeared at a given location despite their brief presentation and rapid succession, that is, temporal object segmentation. Here we examined the role of magnocellular neurons in this process. We measured temporal object segmentation via object substitution masking (OSM), which reflects the failure to distinguish the target and mask as distinct objects through time. We isolated the selective role of magnocellular neurons by comparing performance under conditions of pulsed luminance pedestals, which are designed to saturate the magnocellular response, with that in a steady-pedestal condition that leaves both magnocellular and parvocellular channels available to process the target. Across two experiments, we found that OSM magnitude was enhanced under pulsed-pedestal conditions, in which the magnocellular response was impaired. This indicates that magnocellular neurons contribute to temporal object segmentation. Given that temporal object segmentation has consequences for which stimuli are consciously perceived, this demonstrates a functional mechanism via which magnocellular neurons contribute to determining the contents conscious perception. Implications for models of specialization of dorsal and ventral cortical streams are discussed.Discovery Early Career Researcher Award - Grant ID: DE140101734 [ 2014 - 2016

Personality and its fitness consequences in the Seychelles warbler (Acrocephalus sechellensis)

In this thesis, I investigate whether differences in behaviour among individuals, termed personality, are genetically determined and/or shaped by state and whether personality influences reproductive success and strategy. Using the Cousin Island population of Seychelles warbler (Acrocephalus sechellensis), I measured five personality traits: exploration of a novel object, exploration of a novel environment, obstinacy, stress response and escape response. I estimated the repeatability of each trait, the heritability of the repeatable traits and tested for correlations among repeatable traits. I found that exploration of a novel environment and object were repeatable and correlated, and novel environment exploration was heritable, suggesting that it may be under selection in the population. I then used a candidate gene approach to further investigate the genetic variation associated with personality, specifically targeting SERT and DRD4. I found no genetic variation in DRD4, but identified four polymorphisms in SERT that did not correlate with the novel environment or novel object exploration. These results suggest there was no association between these behaviours and variation in the candidate genes tested in this population, and that a genome-wide study might be beneficial to detect the relevant genes underlying personality. I then looked at how personality is potentially generated and maintained in a social living species by investigating whether personality is social state-dependent or reproductive state-dependent. I found that the novel environment and novel object exploration were not correlated with social status and behavioural consistency was unaffected by social status. Novel object exploration was instead associated with the interaction between insect abundance at year of birth and age (a proxy for reproductive state). Lastly, I investigated the fitness consequences of personality, particularly looking at its influence on reproductive behaviour. I found that disassortative pairs for novel environment exploration were more likely to have females engage in extra pair parentage, and that novel environment and novel object exploration were not associated with the number of offspring sired or the ratio of within to extra group young. Overall my results show that there are consistent among individual differences in behaviour in wild cooperative breeders that may be generated by future fitness potential and are associated with reproductive behaviour within the social pair

Limaria hians (Mollusca : Limacea): a neglected reef-forming keystone species

1. A key component of physical habitat along braided river systems is the exposed riverine sediment within the active zone. The relatively unmanaged, gravel-bed Fiume Tagliamento, Italy, provides the focus for exploring two ecologically important properties of exposed riverine sediments: their within-patch and between-patch variability in calibre. 2. To characterize between-patch variation in exposed riverine sediments, replicate (within-patch) samples were obtained from three geomorphologically distinct locations along 130 km of the river: bar heads along the margin of the low-flow channel, the heads of major bars across the exposed surface of the active zone, and floodplain surfaces. A photographic technique enabled rapid and consistent field sampling of the coarse sediments at bar heads along the low-flow channel margin and on major bars across the dry bed. 3. A downstream decrease in particle size and an increase in within-patch heterogeneity in sediment size were observed within bar head sediments along the margin of the low-flow channel. Comparisons between major bar and low-flow channel samples revealed greatest within-patch variability in individual sediment size indices (D50, A- and B-axes of the larger particles) at headwater sites, greatest between-patch variability in the three measured indices in the central reaches, and lowest between-patch variability at downstream sites. However, there was a distinct increase in the overall heterogeneity in particle size, which was sustained across all patches, in a downstream direction. 4. There was a clear downstream decrease in the size of floodplain sediments in the headwaters, but thereafter there was no distinct downstream trend in any of the calculated particle size indices. 5. The geomorphological controls on the observed patterns and the potential ecological significance of the patterns, particularly for plant establishment, are discussed in relation to the relative relief of the active zone, and the highly variable hydrological and climatic regime along the river

Two objects or one? similarity rather than complexity determines objecthood when resolving dynamic input

The human brain is continuously confronted with dynamic visual input, and from this it must infer whether input belongs to a single versus multiple object identities across time. Object substitution masking (OSM), in which perception of a target stimulus is impaired by a temporally trailing 4-dot mask, reflects a failure to segment the target and mask as discrete objects. According to Bouvier and Treisman (2010), OSM only occurs for targets that require binding multiple separate features (e.g., color and orientation) to be identified. In contrast, a target that represents a unique feature is thought to be impervious to masking. Here, however, we show that a single orientation target (a Gabor) is susceptible to masking with an orientation-discrimination task, but only when the mask is similar in orientation to the target. That is, target-mask similarity, rather than target complexity determines masking. A reexamination of Bouvier and Treisman’s (2010) results show that they can be explained within this target-mask similarity perspective. This means that the similarity of 2 objects determines whether they will be integrated or segmented across time, rather than the complexity of 1 of the objects in isolation.The research was supported by an Australian Research Council grant: arc ID:de140101734

Exploration is dependent on reproductive state, not social state, in a cooperatively breeding bird

Personality is an intriguing phenomenon in populations because it constrains behavioral flexibility. One theory suggests that personality could be generated and maintained if dependent on asset protection. It is predicted that trade-offs with fitness expectations and survival probability encourage consistent behavioral differences among individuals (personality). Although not mutually exclusive, the social niche specialization hypothesis suggests that a group of individuals that repeatedly interact will develop personality to avoid costly social conflict. The point at which behavioral consistency originates in the social niche hypothesis is still unclear, with predictions for development after a change in social status. In the facultative cooperatively breeding Seychelles warbler (Acrocephalus sechellensis), residing on Cousin Island, breeding vacancies are limited and this forces individuals into different social roles. We used this system to test whether reproductive and social state predicted among-individual differences in exploration. We had 2 predictions. First, that an individual’s start in life can predict personality, whereby young individuals with a good start to life (associated with early age reproduction and earlier onset survival senescence) are fast explorers, suggesting reproductive state-dependence. Second, that an individual’s social status can predict personality, whereby dominant individuals will be fast explorers, suggesting that the behavior is social state-dependent. Neither of the behaviors was associated with social state and social state did not affect behavioral consistency. However, novel object exploration was associated with a proxy of reproductive state. Our results provide further support for state being a mechanism for generating individual differences in behavior