Report
Teaser, summary, work performed and final results
Periodic Reporting for period 1 - PtoACons (Going from Phenomenal to Access Consciousness: Neurobehavioural correlates of visual consciousness development and its underlying cognitive procesess.)
Teaser
\"Over the past decades, neuroscientists have devoted substantial effort to understand what visual consciousness is, and which are the neural correlates underlying its content. A critical contribution to consciousness research distinguishes between two concepts of...
Summary
\"Over the past decades, neuroscientists have devoted substantial effort to understand what visual consciousness is, and which are the neural correlates underlying its content. A critical contribution to consciousness research distinguishes between two concepts of consciousness: phenomenal and access consciousness. According to Block (1996), phenomenal or P-consciousness represents the experiential properties of our perceptions (e.g., sensations, feelings). On the other hand, access or A-consciousness refers to the process by which a phenomenally conscious perception is made available to other cognitive mechanisms (e.g., memory, reasoning). Interestingly, Lamme (2003) proposed a model in which these two types of consciousness are related to different processing stages of the information. At a first stage after a visual stimulus reaches our senses, many visual representations are available in P-consciousness, which is implemented by local recurrent activations between the early visual areas of our brain (Figure 1 yellow lines). The content of P-consciousness has been commonly associated with measures of iconic memory, which is a sort of \"\"snapshot\"\" of what we are perceiving (Figure 1a). Subsequently, the activations in the early visual areas feed-forward to higher level visual areas; however, as time passes, these activations lose strength causing a reduction of the high-resolution phenomenal representations created in first stages, giving place to fragile short-term memory content (Sligte, Vandenbroucke, Scholte & Lamme, 2010; Figure 1b). At this stage, the competition between representations increases, and only those engaging in global recurrent activations from visual areas to the frontal part of our brain (Figure 1 red lines) evolve in A-consciousness. At this stage, only part of the original phenomenal experience gains access to higher cognitive processes. The content of A-consciousness has been related to working memory (Figure 1c).
The route from P- to A- consciousness involves several cognitive processes, such as attention, memory, decision-making and metacognition, which are intermingled and spatiotemporally overlaped.
Due to this complex overlap, the study of visual consciousness needs to be carried out in a comprehensive framework. Therefore, the present project pursues two general aims: 1) To dissociate the behavioural responses and neurofunctional correlates of P- and A- consciousness, distinguishing between objective and subjective measures. 2) To elucidate how the cognitive processes of attention, (iconic and working) memory and their interactions are involved in the development of the conscious content. Better understanding of the neural basis of attention, visual consciousness, and metacognition may aid in developing solutions for societal problems by, for example, implementing new devices of road safety and programs of interventions aimed at improving academic success.\"
Work performed
During this first period, we have performed three behavioural experiments, whose main goal was to investigate how the modulation of different types of attention affects visual awareness.
At this aim, we used a change-detection paradigm (see Figure 2) in which participants had to indicate whether a probed item (a letter) was the same or different to the item shown at that corresponding location in the memory array. Afterwards, participants were asked to rate their confidence about their response. The cue-probe indicating the location of the probed item was presented at different latencies to test different stages of information processing (iconic, fragile visual short-term and visual working memory; see Vandenbroucke et al.2011).
Two types of measures have been collected in each memory condition: 1) sensitivity measures (d’) as objective measures and 2) mean confidence ratings as subjective measures.
Attention before the memory array presentation was manipulated in three different ways: by asking participants to voluntary direct their spatial attention to a specific location; by automatically attracting participant’s spatial attention to a specific location by the presentation of a salient stimulus; and by asking participants to perform the change detection task alone (no load condition) or while trying to simultaneously carrying out a calculation problem (high load condition; double task).
Results.
When attention was voluntarily directed, the impact of attention on sensitivity changed depending on the memory condition, with larger attentional modulations at later stages (working memory) than at earlier stages (iconic memory) of information storage. When participants voluntarily direct their attention, they were able to accurately judge their performance.
When attention was automatically captured by a salient stimulus, attentional modulations on sensitivity were the same independently of the memory condition. Interestingly, the effect of attention on confidence ratings depended on the condition of memory. Despite sensitivity at attended locations was significantly higher for iconic memory than for working memory, participants were not aware about it.
The reduction of attentional control due to the engagement in a double-task, produced a decrease of sensitivity, which was independent of the memory condition. Interestingly confidence ratings were not modulated by the attentional load: even though participants’ sensitivity was higher in the no-load than in the high-load condition, their confidence in their response was the same, suggesting that they were not conscious about the reduction of their memory performance.
Final results
The present study is framed within the field of research concerning the relation between attention and consciousness. Recently, some authors have claimed that attention and consciousness can be completely dissociated, thus questioning the traditionally accepted view conceiving consciousness and attention as inextricably related processes. According to these authors (e.g Lamme 2006), consciousness arises as a result of recurrent processing, while attention is dependent on the depth of processing. The prediction is that when recurrent processing is local and involves only visual areas, the representations are phenomenally conscious, meaning that phenomenal or P-consciousness is independent of attentional modulations. However, our results seem to suggest exactly the opposite, by showing that all stages of information processing are reliably affected by the distribution of attentional resources. The fact that iconic memory was reliably modulated by attention, suggests that also phenomenal consciousness, as access consciousness, might depend on attentional system.
Moreover, we observed that different ways of directing our spatial attention can give place to different outputs in metacognition. In particular, our results suggest that when we attend to a specific location in a voluntary fashion, we are more precise in judging our own memory performance. Contrariwise, attention automatically captured by salient stimuli can lead to metacognition errors leading us to erroneously believe that we remember more than we are effectively able to remember. This last result, which will need to be replicated in future studies, could be particularly interesting for developing new educational training programs in which the use of voluntary attentional strategies is promoted as a means to improve metacognitive skills.