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The behavior of bees is modulated by the presence of other bees and potentially by the visual information transmitted by the different body positions of bees while visiting flowers. We tested whether bee body position promoted the attraction and/or antagonistic behavior of con- and hetero-specific bees that interacted on prickly pear flowers of Opuntia huajuapensis. To test this, we placed dummy model bees of Apis mellifera and the native Lithurgus littoralis in flowers in three common body positions: alert, feeding, and horizontal. The results showed that dummy model bees in feeding and horizontal body positions attracted A. mellifera bees, while the alert position attracted native male L. littoralis. Male L. littoralis bees spent more time attacking model bees in horizontal and alert positions. The position of dummy bees also influenced response times. Bees of A. mellifera responded fastest to L. littoralis in the alert and horizontal position, male L. littoralis responded fastest to con-specific bees in the alert and feeding position, and female L. littoralis responded fastest to A. mellifera bees in the feeding position. A. mellifera reacted fastest to their con-specific bees in the alert and horizontal body positions. Our results demonstrate, for the first time in bees, that the position of individuals on a floral resource provides important visual information that modulates bee behavior, and illuminates aspects that likely have implications for bees in access to floral resources.

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We compared the effect of visual information on the dominant upper limb position sense of children with diplegic cerebral palsy (n = 10) and normally developing children (n = 10). An isokinetic dynamometer passively moved the dominant forearm in 120° of elbow flexion/extension until the volunteers stopped the machine to indicate that the elbow joint was positioned in the predetermined target angle. Participants performed this task five times in sequence with and without visual feedback of the elbow angle. We calculated the absolute and the relative position errors related to the final elbow position and the target angle. In both groups, absolute error was significantly higher when vision was occluded. Relative error was not affected by cerebral palsy or visual feedback. When vision was occluded, accuracy on this task was similarly impaired in both groups and precision was not disturbed.

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Nós investigamos o efeito da informação visual irrelevante (IVI) na recuperação da informação na memória de trabalho. Os participantes realizaram uma tarefa de reconhecimento visual. Em metade das provas, uma dica retroativa espacial foi apresentada no intervalo de retenção. A IVI, um flicker cromático, com frequências de 1,0 Hz, 7,3 Hz e 15,3 Hz, foi apresentada no intervalo entre dica e teste. A dica melhorou a acurácia e a rapidez na tarefa de reconhecimento. O flicker não afetou o desempenho. A dica retroativa pode permitir a recuperação da informação para um estado ativo e pode tê-la protegido da interferência do flicker.

We investigated the effect of irrelevant visual information (IVI) on retrieving information from working memory. Participants performed a visual recognition task. In half of the trials, a retroactive spatial cue was presented in the retention interval. The IVI, a chromatic flicker, with frequencies of 1.0 Hz, 7.3 Hz, and 15.3 Hz, was presented in the interval between cue and test. The cue improved the accuracy and speed of the recognition task. The flicker did not affect performance. The retroactive cue may allow the retrieval of information to an active state and may have protected it from the flicker interference.

Nosotros investigamos el efecto de la información visual irrelevante (IVI) en la recuperación de información de la memoria operativa. Los participantes realizaron una tarea de reconocimiento visual. En mitad de las pruebas, se presentó una pista espacial retroactiva en el intervalo de retención. El IVI, un flicker cromático, con frecuencias de 1,0 Hz, 7,3 Hz y 15,3 Hz, se presentó en el intervalo entre pista y prueba. La pista mejoró la precisión y la velocidad de la tarea de reconocimiento. El flicker no afectó el performance. La pista puede permitir la recuperación de la información a un estado activo y puede haberla protegido de la interferencia del flicker.

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The aim of this study was to analyze the motor and visual strategies used when walking around (circumvention) an obstacle in patients with Parkinson's disease (PD), in addition to the effects of dopaminergic medication on these strategies. To answer the study question, people with PD (15) and neurologically healthy individuals (15 - CG) performed the task of obstacle circumvention during walking (5 trials of unobstructed walking and obstacle circumvention). The following parameters were analyzed: body clearance (longer mediolateral distance during obstacle circumvention of the center of mass -CoM- to the obstacle), horizontal distance (distance of the CoM at the beginning of obstacle circumvention to the obstacle), circumvention strategy ("lead-out" or "lead-in" strategy), spatial-temporal of each step, and number of fixations, the mean duration of the fixations and time of fixations according to areas of interest. In addition, the variability of each parameter was calculated. The results indicated that people with PD and the CG presented similar obstacle circumvention strategies (no differences between groups for body clearance, horizontal distance to obstacle, or obstacle circumvention strategy), but the groups used different adjustments to perform these strategies (people with PD performed adjustments during both the approach and circumvention steps and presented greater visual dependence on the obstacle; the CG adjusted only the final step before obstacle circumvention). Moreover, without dopaminergic medication, people with PD reduced body clearance and increased the use of a "lead-out" strategy, variability in spatial-temporal parameters, and dependency on obstacle information, increasing the risk of contact with the obstacle during circumvention.

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Little is known about the ability of blind people to cross obstacles after they have explored haptically their size and position. Long-term absence of vision may affect spatial cognition in the blind while their extensive experience with the use of haptic information for guidance may lead to compensation strategies. Seven blind and 7 sighted participants (with vision available and blindfolded) walked along a flat pathway and crossed an obstacle after a haptic exploration. Blind and blindfolded subjects used different strategies to cross the obstacle. After the first 20 trials the blindfolded subjects reduced the distance between the foot and the obstacle at the toe-off instant, while the blind behaved as the subjects with full vision. Blind and blindfolded participants showed larger foot clearance than participants with vision. At foot landing the hip was more behind the foot in the blindfolded condition, while there were no differences between the blind and the vision conditions. For several parameters of the obstacle crossing task, blind people were more similar to subjects with full vision indicating that the blind subjects were able to compensate for the lack of vision.

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The selection of alternate foot placement is based on visual inputs.

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The selection of alternate foot placement is based on visual inputs. (AU)

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Although impairments in postural control have been reported due to sleep deprivation, the mechanisms underlying such performance decrements still need to be uncovered. The purpose of this study was to investigate the effects of sleep deprivation on the relationship between visual information and body sway in young adults' postural control. Thirty adults who remained awake during one night and 30 adults who slept normally the night before the experiment participated in this study. The moving room paradigm was utilized, manipulating visual information through the movement of a room while the floor remained motionless. Subjects stood upright inside of a moving room during four 60-s trials. In the first trial the room was kept stationary and in the following trials the room moved with a frequency of 0.2Hz, peak velocity of 0.6cm/s and 0.9cm peak-to-peak amplitude. Body sway and room displacement were measured through infrared markers. Results showed larger and faster body sway in sleep deprived subjects with and without visual manipulation. The magnitude with which visual stimulus influenced body sway and its temporal relationship were unaltered in sleep deprived individuals, but they became less coherent and more variable as they had to maintain upright stance during trials. These results indicate that after sleep deprivation adults become less stable and accurate in relating visual information to motor action, and this effect is observed after only a brief period performing postural tasks. The low cognitive load employed in this task suggests that attentional difficulties are not the only factor leading to sensorimotor coupling impairments observed following sleep deprivation.

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O controle visual da freada foi estudado em ciclistas recreacionais através da manipulação da velocidade no início da freada (baixa, média e alta) e da trajetória de aproximação (retilínea e curvilínea) da bicicleta em relação a um obstáculo estacionário. A hipótese foi que o tipo de trajetória da bicicleta, de modo exclusivo ou em interação com a velocidade inicial, afetaria a informação visual de tempo para colisão ("tau" margem) e sua primeira derivada no tempo ("tau-dot"), respectivamente, no início e durante a freada. Os resultados revelaram que a velocidade afetou significativamente "tau" margem, enquanto "tau-dot" manteve-se inalterado independentemente da condição. O tipo de trajetória claramente não afetou o controle visual da freada em ciclistas.

Braking visual control was studied in recreational cyclists through the manipulation of bicycle's velocity at braking initiation (low, medium, and high) and approaching trajectory (straight and curved) with respect to a stationary obstacle. The hypothesis was that the type of trajectory, exclusively or interacting with initial velocity, would affect time to collision visual information (tau margin) and its first derivative in time (tau-dot), respectively, in the onset and during braking. The results revealed that velocity affected significantly tau margin while tau-dot remained unaltered independently of condition. The type of trajectory clearly did not affect the visual control of braking in cyclists.

El control visual de la frenada fue estudiado en ciclistas recreativos mediante la manipulación de la velocidad (baja, media y alta) al principio de la frenada y la trayectoria de aproximación de la bicicleta (rectilínea y curvilínea) en relación con un obstáculo fijo. La hipótesis era que el tipo de trayectoria de la bicicleta, de modo exclusivo o en interacción con la velocidad inicial, afectaría la información visual del momento de la colisión (margen "tau") y su primera derivada en el tiempo ("tau-dot"), respectivamente, al principio y durante la frenada. Los resultados revelaron que la velocidad afectó significativamente el margen "tau", mientras que el "tau-dot" permaneció inalterado independientemente de su condición. El tipo de trayectoria claramente no afectó el control visual de frenado en los ciclistas.

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