1.Introduced plant species modify the environment and alter ecological interactions in communities, often to the detriment of native fauna, but the causes driving negative effects on fauna are rarely examined. We used native Australian scincid lizards Carlia munda and Carlia pectoralis and the introduced weed rubber vine Cryptostegia grandiflora as a model system to determine the possible underlying mechanisms driving habitat selection by native fauna in an environment invaded by weeds. 2. Lizards were allowed to select between rubber vine and native eucalypt leaf litter in semi-natural enclosures. To determine the mechanisms of habitat preference, we examined differences in temperature, prey (arthropod) availability and composition, and leaf shape of naturally occurring rubber vine and native vegetation. 3. Lizards discriminated between leaf litter types: 85% of Carlia pectoralis and 80% of Carlia munda chose native leaf litter over rubber vine, clearly indicating a preference for native habitat. 4. In the field, rubber vine leaf litter was cooler at the surface than native leaf litter, and during peak lizard activity was below the temperature range of Carlia . Rubber vine also contained significantly fewer arthropod taxa and a significantly different composition of arthropod taxa, with fewer preferred prey items of Carlia than native vegetation. 5. Finally, rubber vine leaves were significantly shorter than native leaves and the lizards themselves. The shape of rubber vine leaves was different from that of the lizards, potentially making the lizards more obvious on rubber vine litter. This may increase the susceptibility of the lizards to detection by predators. 6. Synthesis and applications . In comparison with native habitat, rubber vine provided a suboptimal environment for litter-dwelling lizards because of the lower ambient temperatures, reduced availability of prey and a reduction in camouflage from predators (dissimilar leaf and lizard shapes). Our study has identified three possible mechanisms by which an introduced plant species can alter the availability of resources in an environment, making it less attractive to native fauna. Our results highlight the importance of understanding how alien plants alter the environment and further emphasize the critical need for management of plants that replace native habitat with a suboptimal environment.

Creating a visual representation of an item through drawing affords that item a substantive memory benefit, relative to several control tasks. Recent findings demonstrate the robustness of this drawing effect across several stimulus classes, irrespective of encoding time, setting, age group, or memory measure. The advantage for drawn information has been attributed to the integrated contributions of at least three components of visual production through drawing, which can independently facilitate memory: elaborative, motoric, and pictorial. In the current work, we investigated the importance of the elaborative process one must engage in while preparing to draw, and directly tested whether this generative period alone was sufficient to improve memory. Participants were prompted to either draw or write out presented words, and were provided with a 1- or 2-s preparatory period prior to completing the prompted task. Critically, on a subset of the trials, participants were prevented from completing the prompted task. There was strong evidence in support of better memory for drawn items, which replicates the drawing effect commonly observed in prior work. Interestingly, following prompts to draw, there was also a reliable memory benefit of the preparatory period alone. In other words, simply engaging in the elaborative process of preparing to draw (i.e., without completing the drawing) was enough to produce a reliable increase in later memory relative to actually writing.

Countless experiments have been devoted to understanding techniques through which memory might be improved. Many strategies uncovered in the literature are thought to act via the integration of contextual information from multiple distinct codes. However, the mnemonic benefits of these strategies often do not remain when there is no clear link between a word and its multisensory referent (e.g., in abstract words). To test the importance of this link, we asked participants to encode target words (ranging from concrete to abstract) either by drawing them, an encoding strategy recently proven to be reliable in improving memory, or writing them. Drawing provides a compelling test case because while other strategies (e.g., production, generation) shift focus to existing aspects of to-be-remembered information, drawing may forge a link with novel multisensory information, circumventing shortcomings of other memory techniques. Results indicated that while drawing's benefit was slightly larger for concrete stimuli, the effect was present across the spectrum from abstract to concrete. These findings demonstrate that even for highly abstract concepts without a clear link to a visual referent, memory is reliably improved through drawing. An exploratory analysis using a deep convolutional neural network also provided preliminary evidence that in abstract words, drawings that were most distinctive were more likely to be remembered, whereas concrete items benefited from prototypicality. Together, these results indicate that while the advantageous effects of drawing exist across all levels of concreteness, the memory benefit is larger when words are concrete, suggesting a tight coupling between the drawing benefit and visual code.

Several recent studies have reported enhanced memory when retrieval is preceded by repetitive horizontal eye movements, relative to vertical or no eye movements. The reported memory boost has been referred to as the Saccade-Induced Retrieval Enhancement (SIRE) effect. Across two experiments, memory performance was compared following repetitive horizontal or vertical eye movements, as well as following a control condition of no eye movements. In Experiment 1, we conceptually replicated Christman and colleagues' seminal study, finding a statistically significant SIRE effect, albeit with weak Bayesian evidence. We therefore sought to conduct another close extension. In Experiment 2, horizontal and vertical eye movement conditions were manipulated separately, and sample size was increased. No evidence of a SIRE effect was found: Bayesian statistical analyses demonstrated significant evidence for a null effect. Taken together, these experiments suggest that the SIRE effect is inconsistent. The current experiments call into question the generalizability of the SIRE effect and suggest that its presence is very sensitive to experimental design. Future work should further assess the robustness of the effect before exploring related theories or underlying mechanisms. OPEN ACCESSCitation: Roberts BRT, Fernandes MA, MacLeod CM (2020) Re-evaluating whether bilateral eye movements influence memory retrieval. PLoS ONE 15(1): e0227790. https://doi.org/10.

The enactment effect is the phenomenon that physically performing an action represented by a word or phrase (e.g., clap, clap your hands) results in better memory than does simply reading it. We examined data from three different methodological approaches to provide a comprehensive review of the enactment effect across 145 behavioral, 7 neuroimaging, and 31 neurological patient studies. Boosts in memory performance following execution of a physical action were compared to those produced by reading words or phrases, by watching an experimenter perform actions, or by engaging in self-generated imagery. Across the behavioral studies, we employed random-effects meta-regression with robust variance estimation (RVE) to reveal an average enactment effect size of g = 1.23. Further meta-analyses revealed that variations in study design and comparison task reliably influence the size of the enactment effect, whereas four other experiment factorstest format, learning instruction type, retention interval, and the presence of objects during encoding-likely do not influence the effect. Neuroimaging studies demonstrated enactment-related activation to be prevalent in the motor cortex and inferior parietal lobule. Patient studies indicated that, regardless of whether impairments of memory (e.g., Alzheimer's) or of motor capability (e.g., Parkinson's) were present, patients were able to benefit from enactment. The findings of this systematic review and meta-analysis highlight two components accounting for the memory benefit from enactment: a primary mental contribution relating to planning the action and a secondary physical contribution of the action itself. Public Significance StatementThe enactment effect is the finding that physically performing an action represented by a word or phrase leads to enhanced memory for that information relative to simply reading it. This review integrates evidence from behavioral, neuroimaging, and patient studies to highlight the utility of encoding multiple facets of an item or an event to enhance its retention. Enactment was found to be a reliable and effective mnemonic tool for both neurotypical and patient populations.