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

Abstract

To what extent are shifts of attention driven by encoding of , associated with useful locations, or by encoding of environmental cues that act as, 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 ("") encoding; while attentional effects driven by the symbolic identity of cues may be driven by ventral stream ("") 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

Illuminating the Neural Circuits Underlying Orienting of Attention

“…A recent paper from Lambert et al [6] identified two forms of orienting of attention. One form, landmark cuing, involves a rapid shift and uses the dorsal pathway through the parietal lobe.…”

Accident Vulnerability and Vision for Action: A Pilot Investigation

“…Although not without critics [9], dual-stream characterisations of visual functioning have been supported by an impressive array of findings from research with animal [10] as well as human [2,11] participants, including neuropsychological, behavioural and neuroimaging [12,13] studies. In extending this framework, Lambert et al [14] noted that shifts of attention, both overt and covert, can be considered visually guided actions, and presented evidence in support of the proposal that rapid shifts of attention are associated with dorsal stream encoding of visual input (see also [15,16]). Viewed from this dual-stream perspective, it seems likely that vision-for-action (including the ability to shift attention rapidly in response to new visual information), rather than vision-for-perception, is likely to be the aspect of visual functioning most closely associated with accident vulnerability.…”

“…However, if one accepts the dual-stream framework just described, it is clear that comprehensive assessment of visual functioning requires the development of alternative approaches, which assess the efficiency of non-conscious visual processing by the dorsal stream [17]. In the current study, we met this challenge by embracing Milner and Goodale's [1,2] description of dorsal stream function in terms of vision-for-action, and assessed the efficiency with which participants could perform a specific kind of visually guided action-moving the eyes in response to a peripherally presented landmark stimulus (see [14]). We predicted that individual differences in vision for action would be related to accident vulnerability, independently of a conventional measure of vision for perception-the Freiburg Vision Test [18], which assesses visual acuity.…”

“…This novel test incorporates design features that target dorsal visual stream processing. Its structure is based on the landmark cueing procedure [14,15,19,20] which combines elements of the attentional cueing techniques devised by Michael Posner and colleagues [4,21] and the landmark learning procedure described by Ungerleider and Mishkin [10]. In landmark cueing, participants shift attention towards a peripheral target object, which is preceded by bilateral cue stimuli.…”

“…Evidence from a number of studies indicates that the dorsal visual stream plays a key role in the featural encoding that drives rapid attention-shifting in response to landmark cues. These include: (1) studies showing that behavioural characteristics of orienting in response to landmark cues correspond with known physiological characteristics of the dorsal visual stream, including sensitivity to low contrast edges, representation of the visual periphery and insensitivity to isoluminant stimuli [14,20,22]; (2) high-density EEG studies, in which source localization has indicated early activation of dorsal stream structures following presentation of landmark cues [15,16,19]; and (3) neuropsychological studies showing that a patient (DF), with bilateral damage to the ventral stream and dense visual-form agnosia was able to shift attention in response to landmark cues, despite being unable to discriminate consciously between alternative cue stimuli [16]. In contrast, a patient with a dorsal stream (parietal-occipital) lesion and optic ataxia was unable to shift attention in response to landmark cues but retained the ability to shift attention in response to symbolic cues [23].…”