Principles of Sensory Science Final Free Essay

Sensory physiology is a field that has received overlapping topics studied by a variety of fields including; cognitive psychology (cognitive science), philosophy of perception, neuroscience among others (Altner et al 2012). Sensory physiology refers to the study of biological processes underlying sensation. Sensory physiology is concerned with how cells convert real-world signals of taste, touch, light, sound, and pain etc. into neural signals. Sensory physiology is concerned with how these sensory receptors work to relay information about stimuli to the nervous system (Altner et al 2012).

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A sense is defined as a physical capacity of organisms that provides data for perception (Martens 1999). The most acceptable definition of a sense across the various fields is "A system that consists of a group of sensory cell types that responds to a specific physical phenomenon and that corresponds to a particular group of regions within the brain where the signals are received and interpreted" (Anderson et al. 2012). Sensory physiology scholars agree that senses can be definitively divided into interoceptive and exteroceptive senses. Interoceptive senses refer to sense that perceives sensations in internal organs while exteroceptive senses, on the other hand, are senses that perceive the body's own position, state, and motion commonly referred to as proprioceptive senses. External senses include hearing, touch smell, taste, sight, and thermoception. Proprioceptive senses include proprioception i.e. a sense of the movement and the position of the body, nociception (pain), and equilibrioception senses (balance). There are five 'traditional' senses which are viewed as our connection to the world. These include sight, hearing, sound, taste, smell, and touch. These senses send messages to our brain which in turn interprets the messages and perceives what is around us. It is important to note that a majority of the information that our senses transfer to the brain is never recognized by our brain (Altner et al 2012). What the brain interprets among the thousands of stimuli received by our senses is determined by an individual's experiences, beliefs, and culture. Through the information gathered by the five senses, the brain interprets and perceives the world around us creating our experience of life.

Sight sense also known as vision is the ability of the eyes to distinguish and identify images. This happens when the retina, a part of the eye, creates electrical nerve impulses for the different colors, brightness, and hues (Gunturkun 2000). Rods and cones are the two types of photoreceptors. Cones are responsible for distinguishing between the different colors while rods are sensitive to light unlike cones (Gunturkun 2000). Hearing, on the other hand, is the sense of sound perception (Plack 2018). This sense is all about vibrations created by motion. Motion is turned by mechanoreceptors into electrical nerve pulses which are in located in the inner ear. Hearing is a mechanical sense as a sound is a vibration which is propagated through media such as air, liquid or solid. The vibrations are then mechanically conducted from the eardrum to hair-like fibers in the inner ear through a series of tiny bones. The hair-like fibers detect mechanical motion of the fibers within a range of 20 to 20,000 hertz (Plack 2018). A sense of smell, on the other hand, refers to a sense whereby olfactory receptors are stimulated by chemical molecules suspended in the air when one breathes (Anderson et al. 2012). The messages are then sent to the olfactory bulb at the base of the brain.

Touch sense also referred to as tactician or mechanoreception refers to a perception resulting from activation of neural receptors in the skin, throat, tongue, and mucosa. Lastly, the sense of taste refers to the capability to detect the taste of substances such as certain minerals, food, and poisons among others (Goody 2002). The human body receives tastes through sensory organs called taste buds also known as gustatory calyculi which are concentrated on the upper surface of the tongue (Goody 2002).

Sensory physiology has been applied in different aspects and researches to investigate and study the reaction of human beings to different substances and stimuli in the world. This essay seeks to discuss sensory physiology in relation to food. In particular, this essay seeks to discuss the statement 'The Human body is a finely tuned instrument that uses its five senses to detect, perceive and recognize signals in food'. In order to achieve this discussion will consider the argument that flavor profiles of food are built in the brain through multimodal interaction of senses.

Sensory evaluation (Sensory analysis) refers to a scientific discipline that applies principles of experimental design and statistical analysis to the use of human senses for the purposes of evaluating consumer products (Cheng & Engelen 2012). This scientific method is used to evoke, measure analyze and interpret human responses to products as perceived through the senses. As a field sensory evaluation emerged in the 1940s and has since then developed as an exciting, dynamic, constantly evolving discipline recognized as a scientific field by its own right.

Sensory evaluation can be subdivided into three sub-sections which include analytical testing (dealing with objective facts about products), perception (the biochemical and psychological aspects of sensation) and effective testing (dealing with subjective facts such as preferences). The main categories of sensory evaluation testing include subjective and objective testing (Cheng & Engelen 2012). Subjective testing involves the evaluation of the reactions of consumers to a product's sensory properties while objective testing, on the other hand, involves evaluating the sensory attributes by a selected or trained panel.

The combination of objective and subjective testing in sensory evaluation is realized when two elements are combined to reveal insights into the way in which sensory properties drive consumer acceptance and emotional benefits (Cheng & Engelen 2012). The design of a product is influenced by the ability to link sensory properties of humans to the chemical, physical, formulation and process variables of products. A highly evaluated product delivers optimum consumer benefits (Cheng & Engelen 2012). Sensory evaluation is used to investigate and study the reaction of human beings to different substances and stimuli in the world.

The human body senses/perceives and recognizes food attributes e.g. color, shape, appearance; temperature, hand feel; taste, smell; acoustic properties; texture, mouthfeel etc. multimodal interaction of the human body senses transmits chemical signals to the brain to identify food flavor profiles. The human sensory experience is influenced by everything going around us including taste, smell, touch, sound, and sight. Technically the human sensory experience is a multimodal perception which includes smell, taste, touch, sight and sound senses. The interaction of these senses influences a humans experience with food and beverages. In the human body, taste experience is an accumulation of multiple senses. Philosophers and scientists argue that taste experience in humans refers to a multimodal experience where the stimulation of one sense causes a perception in a different sense (Auvray and Spence 2008). The traditional 'tongue map' which showed the various places where a human felt taste i.e. bitter, sour, sweet and salt has been reduced to a myth by the recent studies in the field of sensory philosophy. Instead, research suggests that we taste, bitter, sour, salt and sweet in many places on the tongue and are influenced by a multimodal stimulation of the five senses (Auvray & Spence 2008).

The chemical sense of taste in human and most animals involves the detection of five basic taste categories of sour, sweet, bitter, salty and umami (Chaudhari & Roper 2010). Tastant molecules bind (either directly or indirectly) to ion channels in the membranes of taste receptor cells in the mouth, which are organized into taste buds (Chandrashekar, Hoon, Ryba & Zuker 2006). From there, the signal is converted and sent to the brain in a process known as transduction (Frank & Hettinger, 1992). However, substances are very rarely delivered into the mouth in the form of pure tastes (Frank & Hettinger, 1992). Most consumption is of foodstuffs that have complex flavors involving not only taste but also texture (Philipsen 1995), temperature (Talavera et al. 2007), other tactile sensations (Cardello 1996) and trigeminal nerve irritation (such as the burning sensation of capsicum pepper or cooling of menthol (Lawless & Stevens 1984). For these reasons flavor is arguably multi-sensory, and it also shows influences from other senses such as olfaction (Small et al. 2004), and vision (Auvray & Spence 2008). The integration of multiple senses when eating appears to be supported anatomically via the orbital frontal cortex (OFC) which is implicated as the site of integration for the components of flavor, and this serves as a "higher-order gustatory cortex" (Small et al. 2007, p. 136).

Different studies have reported a wide range of cross-modal associations relating to the perception of food. These studies tend to measure one modality while manipulating the other. For example, the researcher varying the color of food while eliciting taste/flavor judgments from participants. Researchers in other studies ask participants to make intuitive matches across the senses. For example, asking participants to choose what shape best fits the taste. According to a study conducted by Philipsen et al (1995) a variety of cross-modal influences flavor, taste, and smell of food. The researchers in this study suggested that color affects both smell and taste/flavor of food. In another study conducted by Johnson and Clydesdale (1982), the researchers found out that color affects the evaluation of specific taste components within foods. In a study conducted by Zellner and Durlach (2003) to investigate the impact of color on refreshment level in different beverages, found out that participants rated the almost clear liquids as the most refreshing. This is due to the fact that we have known water for a long time. People will tend to classify a food that has the wrong color as less refreshing compared to properly colored foods.

Smell too influences the flavor of food. Researchers suggest that smell is certainly one of the larger players (senses) in the organoleptic experience (taste). According to Stevenson and Tomiczek (2007), both taste and smell are sent to the brain via different pathways. However, they converge in the orbitofrontal cortex which is located in the front of the brain behind the eyes. The researchers also argue that smells can suppress tastes and at the same time, smells can suppress sour flavors. This means that suppression of flavors is from a perceptual level as opposed to a physiological level. The human body perception of sweetness intensity can be altered by smell and thus the level of sweetness is not altered physically. At the same time, taste can also influence the smell. According to Stevenson and Tomiczek (2007), fats and irritants are some of the categories of smells that can make us taste differently. Other researchers have found out that a menthol smell was reported by participants to be more intense when a sweet taste was added to it (Davidson et al. 1999).