Marchetti’s Attention-Based Theory

Theorist Giorgio Marchetti maintains, following Damasio (1998), that the phenomenal aspect of consciousness (PAC) provides the agent with a sense of self and with information about how its own operations affect its self. The PAC, Marchetti argues, is produced by attentional activity, which modulates the energy level of the neural substrate—namely, the organ of attention—that underpins this activity. The hypothesis that attentional activity produces such modulation is based on observations of the extreme consequences it can bring about. One example is the sensation of pain, which primarily consists of an interruption in the normal flow of attention (Marchetti, 2010, 2018, 2022).

Marchetti builds on the model of attention that he says best aligns with the conception of an organ of attention, developed by Tamber-Rosenau & Marois (2016). They conceptualize attention as a structured mechanism composed of multiple levels and parts, each with distinct functional roles: a central level for abstract, cognitive processes; a mid-level containing priority maps that bias competition across representational formats and sensory modalities; and a peripheral level for sensory processes. According to this model, the organ of attention can be conceived as being structured across various levels and parts, each underpinning one of these distinct roles.

Phenomenal Aspect of Consciousness

Marchetti’s PAC is characterized by five dimensions:

1. Qualitative: the what-it-feels-like of an experience (e.g., what it feels like “to see red” vs. “to smell garlic”);
2. Quantitative: the intensity of an experience;
3. Hedonic: the pleasantness, unpleasantness, or neutrality of an experience;
4. Temporal: the duration of an experience;
5. Spatial: the egocentric perspective in which an experience is embedded.

Each dimension of the PAC can be explained by a specific aspect of the modulation of the energy level of the organ of attention:

1. The qualitative dimension is defined by the specific area of the organ of attention that underpins and is consequently modulated by attentional activity.
2. The quantitative dimension is defined by the amplitude of the modulation.
3. The hedonic dimension is defined by the direction of the modulation—that is, whether the energy level moves toward or away from the set-point at which it is set. In this view, pleasant and unpleasant experiences occur when the energy level moves toward or away from the set-point, respectively.
4. The temporal dimension is determined by the periodic nature of attentional activity—a nature that limits the duration of the modulation and, consequently, of any conscious experience. This limit is primarily with the support of working memory.
5. The spatial dimension is determined by the egocentric spatial nature of attention. Attention originates from a single point located inside the body and is directed toward something. The path attention takes is reflected in the path of the modulation within the organ of attention.

Self and Its Features

According to Marchetti, the sense of self supplied by the PAC is characterized by several fundamental features, the main ones being:

1. The sense of being an entity differentiated from other entities, which provides the agent with a sense of mineness or ownership;
2. The point of view or perspective from which any content is experienced;
3. The feeling of continuity—that is, the experience of an uninterrupted flow;
4. The feeling of unity, or a “single voice,” meaning the sense of being an organism composed of multiple interconnected parts functioning in a unified way.

These features do not always have to be present simultaneously. Depending on the state of arousal—e.g., conscious wakefulness, REM sleep, vegetative state, near-death experience—and the mode of self-consciousness—e.g., spatial, bodily, or cognitive—some of these features may be altered or even entirely absent.

Each of the main features of the self is shaped by one or more of the five dimensions of the PAC:

• The sense of being an entity differentiated from others is primarily enabled by the hedonic dimension;

• Perspective is shaped by the spatial dimension;

• The feeling of continuity by the temporal dimension;

• The feeling of unity by the concurrent support of the qualitative, quantitative, temporal, and spatial dimensions.

Information about how the agent’s self is affected by the agent’s own operations can be conveyed by any of the five PAC dimensions. The most relevant information is provided by the hedonic dimension, as it indicates the extent to which the energy level of the organ of attention deviates from its set-point, thereby signaling what is and what is not under the agent’s control.

Implications of the Theory

Marchetti says that some implications of his attention-based theory of consciousness are:

1. Attention is necessary for consciousness—there can be no consciousness without attention (Marchetti, 2012);
2. Conscious experience always implies at least a minimal level or form of self, even if some of the self’s features may be absent (Marchetti, 2024);
3. The self is not simply given, but must be learned and achieved through a continuous process of differentiation—primarily fostered by conscious experience—between the agent and other entities. Conversely, the ongoing development of the self leads to changes in how the individual experiences the same event or object.
4. Consciousness also accounts for major symbolic domains of human activity, such as language and art (Marchetti, 2023).