Davidson, Graeme
(2015)
Motivational dynamics: the interaction of motivational and affective systems on
implicit processing of food stimuli.
PhD thesis, University of Liverpool.
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Abstract
The studies reported here were intended to examine how affective and motivational factors influence attentional processing of goal objects, such as food, by exploiting modified versions of an Emotional Blink of Attention (EBA) task originally reported by Piech, Pastorino & Zald (2010). Attentional capture by food distractors presented within a rapid serial visual stream (RSVP) was measured by the extent to which they induced an attentional blink and prevented the correct identification of a subsequently presented, specific visual target. Initially, we explored temporal changes in attention to food images in relation to spontaneous changes in appetite that naturally occur before and after a sandwich lunch. Replicating earlier reports that fasting-induced hunger increases attention to food images, we found that attention to food depended on the level of appetite: increasing pre-prandially as hunger increased, and falling to a minimum after satiation. Moreover, changes in attention to food were seen to reflect subjective ratings of food pleasantness associated with the phenomenon of sensory-specific satiety. Notably, images of the consumed food became less distracting after lunch than images of non-consumed foods belonging to the same sandwich category or, more particularly, those representing very different food types. The EBA data also demonstrated that attentional bias for images of highly palatable, highcalorie desserts was largely immune to changing levels of appetite. Subsequent experiments confirmed that high palatability/high calorie foods with high intrinsic incentive value (cheesecake) potently capture attention even after being eaten to satiety. By contrast, satiation on palatable, sweet fruits did produce sensory-specific changes in attentional bias to fruit images in the EBA. These findings indicate that attention to food images is dependent, via separate processes, on the motivational salience and incentive value of food stimuli. It was noted that affective state (measured using PANAS) varied with appetite level: satiety was associated with a reduction in negative affect and increased positive affect. The relationship between affect, eating motivation and attention were explored further using an ‘Affective EBA’ paradigm, in which neutral filler images within the RSVP were substituted by images of faces displaying positive or negative emotions. Positive affective priming using this technique resulted in an enhancement of attentional bias to food distractors (but not to neutral or romantic distractors). Negative priming, by contrast had no effect. A final experiment explored whether the ability of positive affective priming to increase attentional bias to food might attenuate the previously noted, food-specific, postprandial decline in attentional capture by food stimuli. We found that in sated individuals, positive priming did produce a general increase in attention to food which was in opposition to the expected, satiety-related decline in attentional bias. Overall, the present findings strongly support a key role for attentional mechanisms in the processes that mediate the influence of motivational and incentive salience in energizing and directing goal-related behaviours, such as food seeking and consumption.
| Item Type: | Thesis (PhD) |
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| Additional Information: | Date: 2015-11 (completed) |
| Divisions: | Faculty of Health and Life Sciences > Tech, Infrastructure and Environmental Directorate |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 01 Sep 2016 11:44 |
| Last Modified: | 17 Dec 2022 02:10 |
| DOI: | 10.17638/02002240 |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/2002240 |
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