Testing the unified model of vision and attention: Effects of landmark features, stimulus identity and visual eccentricity on visual orienting and conscious discrimination

ABSTRACT

The unified model of vision and attention (Lambert, A. J., Wilkie, J., Greenwood, A., Ryckman, N., Sciberras-Lim, E., Booker, L.-J., & Tahara-Eckl, L. [2018]. Towards a unified model of vision and attention: Effects of visual landmarks and identity cues on covert and overt attention movements. Journal of Experimental Psychology: Human Perception and Performance, 44, 412–432) was tested by examining effects of centrally and peripherally presented landmark and identity cues on attentional orienting. When presented centrally, both kinds of cue influenced attention; but, when presented peripherally, landmark cues affected attention, but identity cues did not. Effects of peripheral landmark cues on saccadic latencies and manual response times for discriminating between target stimuli were as large as those associated with central landmark cues. Because the dorsal stream represents peripheral vision quite well, whereas the ventral stream does not, these findings are consistent with our proposal that landmark cues tend to recruit dorsal stream encoding, while identity cues rely on ventral stream encoding. When participants discriminated consciously between stimuli employed as cues in the attentional orienting task, centrally presented stimuli were discriminated more rapidly than peripheral stimuli, regardless of cue type. This is consistent with the view that conscious discrimination of the stimuli used as landmark and identity cues in the orienting task, requires vision for perception and recruits ventral stream encoding.

KEYWORDS:

• Attention
• orienting
• perception
• consciousness
• landmarks

Data availability statement

The data that support the findings of this study are openly available in Mendeley at DOI: 10.17632/t2cjrnhcy9.2.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Anthony J. Lambert http://orcid.org/0000-0001-5715-8245

Notes

1 The slightly higher mean error rate in the central identity valid condition, relative to central identity invalid, raises the possibility that within this condition, validity effects in the manual latency data may simply reflect a speed-accuracy trade-off – see Figure 2, upper-left panel. That is, accuracy may have been sacrificed for speed, in the central identity valid condition. This does not appear to be the case. In the sample as a whole, error rates in the central identity valid condition were equal to or better than error rates in the central identity invalid condition for 14 participants. The latency advantage for central identity valid compared to central identity invalid trials was statistically reliable for these participants (t(13) = 2.12, p = .027, one-tailed) and did not differ from the validity effect observed for the remaining sixteen participants, F < 1.

2 Although manual responses quicker than 150 ms and slower than 1500 ms were excluded from our analyses, it is possible that this procedure failed to effectively exclude outliers, raising the possibility that the pattern of results described above and illustrated in the upper panels of Figure 2 may have been influenced and potentially distorted by outliers. To rule out this possibility a more stringent outlier exclusion procedure was applied, which excluded long responses greater than three standard deviations from the mean for that participant, and short responses less than 150 ms or less than three standard deviations from the mean for that participant. An identical pattern of statistically reliable findings was obtained.

3 Cue encoding will, of course, involve simultaneous processing by the dorsal and ventral visual streams, and in the latter case cue stimuli are likely to access the so-called visual word form area (VWFA) in the mid-fusiform gyrus. VWFA is known to be recruited for processing of letters and other symbolic stimuli such as numbers (Hannagan, Amedi, Cohen, Dehaene-Lambertz, & Dehaene, 2015). However, symbolic encoding of letters does not appear to be within the processing repertoire of the dorsal stream (Milner & Goodale, 2006; Peelen & Caramazza, 2012). Therefore, we contend that the dorsal-stream encoding that drives attentional orienting in the Landmark condition relies on featural rather than semantic/symbolic distinctions between the cue stimuli (see Lambert et al., 2018 for detailed discussion). Consistent with this interpretation, similar findings have been obtained from studies employing simple, non-symbolic stimuli, such as lines varying in orientation, as landmark cues (Lambert, Naikar, McLachlan, & Aitken, 1999).

Additional information

Funding

This research was supported by the Royal Society of New Zealand Marsden Fund [Project Number: 3711736].