Tricky to define.
Here’s an attempt by Wolfe et al (2003) [Changing Your Mind: On the Contributions of Top-Down and Bottom-Up Guidance in Visual Search for Feature Singletons, JEP:HPP, 29, 483-502]:
When you look at Figure 1 [a picture with some shapes and things, in the middle of which is a spiky object], your attention is probably attracted to the spiky diamond. It is a salient item, and, all else being equal, salient items that are different from their neighbors tend to attract attention (Egeth, 1977; Julesz, 1986; Moraglia, 1989). The information that guided your attention to that item can be labeled as bottom-up—meaning that it did not depend on the observer’s knowledge of the stimulus. The stimulus itself provides the guidance.
If you are now asked to find the white vertical lines, you can do this with no particular difficulty. The stimuli did not change when you performed the second task. Instead, you changed your mind in response to the suggestion that you look for white verticals. You can find white verticals by guiding your attention to the intersection of the set of white items and the set of vertical items (Wolfe, Cave, & Franzel, 1989). The information that guided your attention in this case can be labeled top-down—meaning that it depended on the observer’s knowledge.
Not sure I like this. I see what they’re getting at, but it’s as if in one case the outside world is causing something whereas in the other case it’s being caused by the head. In reality, there must be some encoding of knowledge which causes one to view a particular stimulus as more salient than another, even in the absence of a feeling of control.
Another (Hahn et al, 2006 [Neuroanatomical dissociation between bottom–up and top–down processes of visuospatial selective attention, NeuroImage, 32, 842-853]):
Bottom–up or exogenous attentional control is stimulus-driven, i.e., attention is spontaneously oriented towards an oncoming stimulus. Top–down or endogenous attentional control, by contrast, is intentional and cognitively driven, i.e., directed by knowledge, expectation and current goals.
I definitely don’t like this. If you’re using cognitive models then everything is cognitive. Percepts don’t just move directly from world to mind. There must be some goal achieved by orienting to a stimulus, perhaps just not the main goal being processed at a particular time.
Some more [previously] scribbles on Burgess et al’s review of BA10… This stuff builds upon Shallice’s Supervisory Attentional System (SAS), a theory of behavioural organisation in which there are four levels:
- Cognitive/action units (e.g. particular actions like reaching).
- Schemata (groups of cog/action units, tied together if they often appear together)
- Contention scheduling (quick selection of actions in routine behaviours)
- Supervisory Attentional System (the bit that does what feels like deliberation)
Types of cognition, according to the authors:
- Stimulus oriented thought (SOT): provoked by something sensed or oriented towards something sensed
- Stimulus independent (SIT): examples include daydreaming, rumination, introspection.
Many include a mixture of both and there will be continual competition. Again, an attempt to get at top-down versus bottom-up type distinctions. Though this is nicer, I feel.
Here’s a picture of version 2 of their theory (from Burgess et al, 2007).
Paul W. Burgess, Jon S. Simons, Iroise Dumontheil, and Sam J. Gilbert. (2005). The gateway hypothesis of rostral prefrontal cortex (area 10) function. In J. Duncan, L. Phillips, & P. McLeod (eds.), Measuring the Mind: Speed, Control, and Age. Oxford University Press, Oxford. pp. 217-248.
Burgess, P. W., Dumontheil, I., & Gilbert, S. J. (2007). The gateway hypothesis of rostral prefrontal cortex (area 10) function. Trends in Cognitive Sciences, 11, 290-298.