Humans sensory stimulus

An animal s needs for stimulus diversity are difficult both to define and quantify (Carlstead 1996). Enrichment is often anthropomorphically rather than ecologically relevant (Chamove 1989), and due to human sensory biases we may fail to realize the importance of olfaction to less charismatic species, or those species with lower perceived levels of olfactory awareness (Hancox 1990 Somerville and Broom 1998). 

The lethal oral dose in humans is probably around 100, but doses as low as 16 mg have reportedly been fatal whereas doses of 2 000 mg have been survived. After ingestion, effects usually occur within 10-30 minutes and include stiffness of the face and neck muscles and increased reflex excitability. Strychnine acts by altering nerve impulses in the spinal cord, resulting in a decreased threshold for stimulation, and, hence, a hyperexcitable state. Any sensory stimulus may produce a violent motor response that, in the early stages of intoxication, tends to be a coordinated extensor thrust and, in later stages, may be a tetanic convulsion with opisthotonos anoxia and cyanosis develop rapidly. Between convulsions, muscular relaxation is complete, breathing is resumed, and cyanosis lessens. Because sensation is unaffected, the convulsions are painful and lead to overwhelming fear. As many as 10 convulsions separated by intervals of 10-15 minutes may be experienced, but death often occurs after the second to fifth convulsion, and even the first convulsion may be fatal if sustained death is commonly due to asphyxia.If recovery occurs, it is remarkably prompt and complete despite the violence of the illness muscle soreness may persist for a number of days. ... 

Scharf and Buus, 1986] Scharf, B. and Buus, S. (1986). Stimulus, physiology, thresholds. In K.R. Boff, L. K. and Thomas, J., editors, Handbook of Perception and Human Performance, chapter 14, Basic sensory processes II. Wiley, New York. 

The human inner ear is embedded in the temporal bone and houses the sensory epithelia of the cochlea and vestibular apparatus (Fig. 1). The sensory epithelia contain hair cells which transduce the stimulus of sound or motion into nerve impulses. Hair cells are equipped with an apical mechano-sensitive apparatus made up by three rows of actin-containing stereocilia of increasing length. Displacement of the stereocilia towards the longest row opens (gates) mechano-electrical transduction channels, whereas deflection into the opposing direction closes the channels [12],... 

If human olfaction can discern the filamentous character of scent plumes in air, then a headspace analysis, no matter how complete, might not suffice to reconstruct the fragrance. The distribution of molecules would play a role, as would the rate with which they are replenished after they have been depleted by sniffing. If, on the other hand, olfaction (independent of other sensory inputs) cannot differentiate a heterogeneous stimulus from one that has been well mixed with air, then a complete chemical analysis could serve to archive odors. 

Sensory analysis is concerned with quantifying human responses to stimuli. It is a precise, descriptive and measuring technique that characterizes the stimulus. In this case, the particular concern is to evaluate the odour of a perfume, perfume ingredient or perfumed product. This is an important process in enabling the perfumer to understand and quantify the sensory characteristics of the product, as only then can they be manipulated in a controlled way as part of the creative process. 

A wide range of factors affect how we perceive a product and how we choose one product in preference to another. The human race is inherently variable in its sensitivity to different sensory stimuli, to such an extent that while some of us, for instance, can smell a musky odour quite distinctly while others are completely blind or anosmic to it. Above this, the way that each of us responds to a stimulus depends on our previous experiences and associations so, while one person may find an odour comforting and nostalgic, another person may be completely indifferent to it. 

Tracking task A laboratory apparatus and associated procedures which have proven one of the most versatile means for assessing and studying the human black-box sensory-motor system by providing a continuous record of a subject s response, via some sensor, to any one of a large number of continuous and well-controlled stimulus or target signals. 

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