Editing Ibn al-Haytham (section)

=== Unconscious inference ===
{{Main|Unconscious inference}}
Alhazen basically states the concept of unconscious inference in his discussion of colour before adding that the inferential step between sensing colour and differentiating it is shorter than the time taken between sensing and any other visible characteristic (aside from light), and that "time is so short as not to be clearly apparent to the beholder." Naturally, this suggests that the colour and form are perceived elsewhere. Alhazen goes on to say that information must travel to the central nerve cavity for processing and:<blockquote>the sentient organ does not sense the forms that reach it from the visible objects until
after it has been affected by these forms; thus it does not sense color as color or light as light until after it has been affected by the form of color or light. Now the affectation received by the sentient organ from the form of color or of light is a certain change; and change must take place in time; .....and it is in the time during which the form extends from the sentient organ's surface to the cavity of the common nerve, and in (the time) following that, that the sensitive faculty, which exists in the whole of the sentient body will perceive color as color...Thus the last sentient's perception of color as such and of light as such takes place at a time following that in which the form arrives from the surface of the sentient organ to the cavity of the common nerve.<ref>{{Cite book |last1=Boudrioua |first1=Azzedine |url=https://books.google.com/books?id=WD0PEAAAQBAJ&dq=the+sentient+organ+does+not+sense+the+forms+that+reach+it+from+the+visible+objects+until+after+it+has+been+a&pg=PA76 |title=Light-Based Science: Technology and Sustainable Development, The Legacy of Ibn al-Haytham |last2=Rashed |first2=Roshdi |last3=Lakshminarayanan |first3=Vasudevan |date=2017 |publisher=CRC Press |isbn=978-1-4987-7940-1 |language=en}}</ref></blockquote>