Aging effects on contrast sensitivity in visual pathways: A pilot study on flicker adaptation

Contrast sensitivity is reduced in older adults and is often measured at an overall perceptual level. Recent human psychophysical studies have provided paradigms to measure contrast sensitivity independently in the magnocellular (MC) and parvocellular (PC) visual pathways and have reported desensitization in the MC pathway after flicker adaptation. The current study investigates the influence of aging on contrast sensitivity and on the desensitization effect in the two visual pathways. The steady- and pulsed-pedestal paradigms were used to measure contrast sensitivity under two adaptation conditions in 45 observers. In the non-flicker adaptation condition, observers adapted to a pedestal array of four 1°×1° squares presented with a steady luminance; in the flicker adaptation condition, observers adapted to a square-wave modulated luminance flicker of 7.5 Hz and 50% contrast. Results showed significant age-related contrast sensitivity reductions in the MC and PC pathways, with a significantly larger decrease of contrast sensitivity for individuals older than 50 years of age in the MC pathway but not in the PC pathway. These results are consistent with the hypothesis that sensitivity reduction observed at the overall perceptual level likely comes from both the MC and PC visual pathways, with a more dramatic reduction resulting from the MC pathway for adults >50 years of age. In addition, a similar desensitization effect from flicker adaptation was observed in the MC pathway for all ages, which suggests that aging may not affect the process of visual adaptation to rapid luminance flicker.

I promessi sposi: entre o cânone e a adaptação parodística na televisão italiana

RESUMO: Para discutir as questões subjacentes à adaptação de um texto clássico para as mídias, tomamos como objeto de estudo uma adaptação em formato de paródia para a televisão. I promessi sposi secondo il trio é uma minissérie em 5 episódios, realizada pela RAI, dirigida e protagonizada pelo trio Lopez-Marchesini-Solenghi, em 1990, que ganhou grande notoriedade nacional, exatamente pelo tom cômico que imprimiu à narrativa manzoniana. Neste trabalho, buscamos identificar as estratégias utilizadas na adaptação do clássico para a paródia e para tal, aplicamos ao texto televisivo parodístico o modelo prático-analítico de Robert Stam (2006), que concebe a adaptação audiovisual em dois níveis: estrutural e contextual. A partir dessa aplicação, utilizamos as categorias propostas pelo autor em todos os níveis de análise, a saber: autoria, personagens, narratologia, ordem, frequência e contexto. Os resultados demonstraram que as ressignificações proporcionadas pela adaptação televisiva ampliaram as possibilidades de interpretação do texto literário, além de consolidarem um processo de atualização de tal obra.Palavras-chave: I promessi sposi. Literatura italiana. Televisão. Adaptação. Paródia. ABSTRACT: Per discutere le questioni alla base dell'adattamento di un testo classico per i media, è stato preso come oggetto di studio un adattamento in parodia per la televisione. I promessi sposi secondo il trio è una mini-serie in 5 episodi, realizzata dalla RAI, diretta e interpretata dal trio Lopez-Marchesini-Solenghi nel 1990, la quale ha acquisito una grande notorietà nazionale proprio per il tono comico che ha impresso alla narrazione manzoniana. Il presente articolo ha cercato di individuare le strategie utilizzate nell'adattamento del classico in parodia, e, a tal fine, è stato applicato al testo televisivo parodistico il modello pratico-analitico di Robert Stam (2006), il quale concepisce l'adattamento audio-visivo in due livelli: strutturale e contestuale. Partendo da questa applicazione, si sono utilizzate le categorie proposte dall'autore in tutti i livelli di analisi, ovvero: paternità, personaggi, narratologia, ordine, frequenza e contesto. I risultati hanno dimostrato come i nuovi significati ottenuti attraverso l’adattamento televisivo abbiano ampliato le possibilità di interpretazione del testo letterario, oltre a consolidare un processo di aggiornamento di quest’ultimo.Parole-chiave: I promessi sposi. Letteratura italiana. Televisione. Adattamento. Parodia. ABSTRACT: In order to discuss the issues underlying the adaptation for the visual media of a classic text, the object of study of the hereby article has been an adaptation, in the format of a parody for the television. I promessi sposi secondo il trio is a mini TV-series consisting of 5 episodes, created by the RAI, directed and interpreted by the trio Lopez-Marchesini-Solenghi in 1990, which gained great national notoriety precisely because of the comedy tone it imprinted on Manzoni’s narrative.The hereby research has tried to identify the strategies used to adapt the classic novel into a parody and, in order to do so, the practical-analytic model by Robert Stam (2006) have been applied to the TV parody text. Such model conceives audio-visual adaptation in two levels: structural and contextual, and applying it, the categories proposed by the author, which are: authorship, characters, narratology, order, frequency and context, have been used in all the levels of the analysis. The results proved how the new meanings obtained through the TV adaptation have widened the possibilities of interpretation of the written text, and have also consolidated a process of updating the novel.Keywords: I promessi sposi. Italian Literature. Television. Adaptation. Parody.

Dynamics of Visual Adaptation With Simultaneous Stimulation of Two Visual Pathways

Primates’ retinal ganglion cells in different visual pathways have been shown to adapt independently (Current Biology 22 (2012) 220–224). However, the manner in which adaptation occurs under simultaneous stimulation of two visual pathways has not yet been explored. In this study, the dynamics of color afterimages were measured while stimulating one or two visual pathway using a time-varying afterimage paradigm. The dynamics of adaptation was approximately equivalent among the three primary visual pathways, but adaptation was slower for simultaneous stimulation of two visual pathways compared to the stimulation of one visual pathway. In addition, we found that the speed of adaptation also depends upon which two pathways are combined. We developed a two-stage adaptation model, both with the same dynamics, to account for the results with simultaneous stimulation of two pathways.

An observer model of tilt perception, sensitivity and confidence

Humans experience levels of confidence in perceptual decisions that tend to scale with the precision of their judgements; but not always. Sometimes precision can be held constant while confidence changes—leading researchers to assume precision and confidence are shaped by different types of information (e.g. perceptual and decisional). To assess this, we examined how visual adaptation to oriented inputs changes tilt perception, perceptual sensitivity and confidence. Some adaptors had a greater detrimental impact on measures of confidence than on precision. We could account for this using an observer model, where precision and confidence rely on different magnitudes of sensory information. These data show that differences in perceptual sensitivity and confidence can therefore emerge, not because these factors rely on different types of information, but because they rely on different magnitudes of sensory information.