A test of the unified model of vision and attention: Effects of parietal-occipital damage on visual orienting.

Visual orienting was studied in a patient (FM) with parietal-occipital damage due to oligodendroglioma and associated surgery, and in eighteen control participants. The ability of FM and control participants to shift attention in response to spatial landmark cues, and in response to cues that recruit endogenous orienting via encoding of cue identity, were assessed. According to the unified model of vision and attention (Lambert, A. et al., Journal of Experimental Psychology: Human Perception & Performance, 44, 412-432) FM should find it difficult to orient attention in response to spatial landmarks due to impaired functioning of the dorsal visual stream; but shifting attention in response to cue identity, encoded via the ventral visual stream, should be spared. Consistent with these predictions, FM was unable to shift attention in the landmark cueing task, but shifted attention effectively in response to identity cues; and her visual orienting performance differed reliably from controls. These findings complement our earlier observation of preserved orienting towards landmark cues in a patient with bilateral damage to the ventral visual stream, and add to a growing body of evidence in support of the unified model of vision and attention.

Landmark cueing and exogenous (onset) cueing: How are they related?

Attentional consequences of (i) mere onset of a peripheral visual cue, and (ii)encoding spatially predictive, landmark features of that cue were studied in two experiments. Target location was associated with landmark features of peripheral cues. Cue onset elicited both attention capture (Experiment Two) and inhibition of return (Experiment One) effects. In both experiments, attentional effects of landmark features of the cues were observed early in practice, and diminished with time on task. Contrary to hypotheses based on models that liken attention to a moving spotlight or zoom lens, in both experiments attentional effects of landmark features were confined to the location where the cue was presented. To explain this, we enlist the concept of attentional priority maps, and propose that visual encoding causes attentional priorities to be updated via alternative input routes and mechanisms. We suggest that onset cueing effects are associated with retinotectal 'spatial indexing', which registers the location, but not the attributes of new stimuli, while landmark cueing effects are associated with interaction between spatial indexing and dorsal stream visual processing of attentionally relevant landmark features.

Accident Vulnerability and Vision for Action: A Pilot Investigation.

Many accidents, such as those involving collisions or trips, appear to involve failures of vision, but the association between accident risk and vision as conventionally assessed is weak or absent. We addressed this conundrum by embracing the distinction inspired by neuroscientific research, between vision for perception and vision for action. A dual-process perspective predicts that accident vulnerability will be associated more strongly with vision for action than vision for perception. In this preliminary investigation, older and younger adults, with relatively high and relatively low self-reported accident vulnerability (Accident Proneness Questionnaire), completed three behavioural assessments targeting vision for perception (Freiburg Visual Acuity Test); vision for action (Vision for Action Test-VAT); and the ability to perform physical actions involving balance, walking and standing (Short Physical Performance Battery). Accident vulnerability was not associated with visual acuity or with performance of physical actions but was associated with VAT performance. VAT assesses the ability to link visual input with a specific action-launching a saccadic eye movement as rapidly as possible, in response to shapes presented in peripheral vision. The predictive relationship between VAT performance and accident vulnerability was independent of age, visual acuity and physical performance scores. Applied implications of these findings are considered.

Sub-threshold cuing: Saccadic responses to low-contrast, peripheral, transient visual landmark cues.

Dorsal stream visual encoding was studied in three experiments, by examining effects of peripheral landmark cues on eye movements. Stimulus features and task structure were tailored to physiological and functional characterisations of the dorsal visual stream. Sub-discriminable peripheral stimuli served as landmark cue stimuli. In Experiments 1 and 2, orienting behaviour in response to cues and targets differed for participants with relatively low and relatively high peripheral contrast thresholds. In Experiment 1, low, but not high-threshold participants oriented towards landmark cues that could not be discriminated consciously. However, in Experiment 3, high-, but not low-threshold participants oriented towards near threshold cues. Hence, under appropriate conditions both groups of participants oriented in response to brief, low-contrast, peripheral information. We propose that landmark cueing may provide a useful tool for measuring individual differences in dorsal stream processing and dynamic aspects of visual functioning and awareness.

Viewing Landscapes Is More Stimulating Than Scrambled Images After a Stressor: A Cross-disciplinary Approach.

Research has demonstrated that nature is beneficial for many aspects of one's health. This pilot study aimed to investigate whether viewing landscape artworks, as a form of representational nature, could improve psychological and physiological recovery from a laboratory stressor. A sample of 30 participants was randomized to one of two conditions: landscape and scrambled. After a laboratory stress task, participants in the landscape condition viewed a series of landscape paintings for 30 min; participants in the scrambled condition viewed digitally scrambled versions of these artworks as a control condition. Pupil size was measured while viewing the images using an eye tracker. Affect, drowsiness and fatigue, and the salivary stress biomarkers, cortisol, and alpha-amylase were measured at baseline, after the stressor, and after the artwork viewing period. After the viewing period, the scrambled condition had increased reports of low negative affect (which contains the variables of sleepy, dull, and sluggish) (p = 0.045, η p 2 = 0.12) and increased reports of drowsiness (p = 0.038, η p 2 = 0.12). Salivary cortisol levels decreased more rapidly while viewing the scrambled images compared to the landscape artworks (p = 0.027, η p 2 = 0.62). Lastly, pupil size while viewing the landscape artworks was larger than when viewing a blank screen (p = 0.025, η p 2 = 0.33), an effect not seen in the scrambled condition. This pilot study suggests that viewing landscape artworks was more stimulating and reduced drowsiness after stress when compared to viewing scrambled images.

Forget about the future: effects of thought suppression on memory for imaginary emotional episodes.

Whether intentional suppression of an unpleasant or unwanted memory reduces the ability to recall that memory subsequently is a contested issue in contemporary memory research. Building on findings that similar processes are recruited when individuals remember the past and imagine the future, we measured the effects of thought suppression on memory for imagined future scenarios. Thought suppression reduced the ability to recall emotionally negative scenarios, but not those that were emotionally positive. This finding suggests that intentionally avoiding thoughts about emotionally negative episodes may inhibit representations of those memories, progressively reducing their availability to recall.

Towards a unified model of vision and attention: Effects of visual landmarks and identity cues on covert and overt attention movements.

To what extent are shifts of attention driven by encoding of visual-spatial landmarks, associated with useful locations, or by encoding of environmental cues that act as symbolic representations, providing information about where to look next? In Experiment 1 we found that when cues were presented with a long exposure time (300 ms) attention shifts were driven by the symbolic identity of cue stimuli, independently of their visual-spatial (landmark) features; but when cues were exposed very briefly, (66 ms), attention shifts were independent of symbolic information, and were driven instead by visual landmark features. This unexpected finding was interpreted in terms of the transient and sustained response characteristics of the M-cell and P-cell inputs to the dorsal and ventral visual streams, respectively, and informed our theoretical proposal that attentional effects elicited by visual-spatial landmarks may be driven by dorsal stream ("where pathway") encoding; while attentional effects driven by the symbolic identity of cues may be driven by ventral stream ("what pathway") encoding. Detailed predictions derived from this proposal, and based on distinct physiological properties of the 2 visual streams were tested and confirmed in Experiments 2-6. Our results suggest that a 2-process view of attention shifting can be integrated with dual-stream models of vision. According to this unified theory: (a) Landmarks associated with visually useful locations elicit rapid, nonconscious shifts of attention, via nonsemantic, dorsal visual stream encoding of their features and spatial relationships; (b) Slower, endogenous shifts of attention are elicited by ventral visual stream encoding of symbolic-semantic information. (PsycINFO Database Record