When identifying letters while reading, not only are theretheir shapes picked up but also other features like their colors and surrounding elements. Individual letters are processed serially when spatially conjoined with another letter. The locations of each feature of a letter are not known in advance, even while the letter is in front of the reader. Since the ___location of the letter's features and/or the ___location of the letter is unknown, feature interchanges can occur if one is not attentively focused. This is known as [[lateral masking]], which in this case, refers to a difficulty in separating a letter from the background <ref>Anne Treisman and Garry Gelade (1980). "A feature-integration theory of attention." Cognitive Psychology, Vol. 12, No. 1, pp. 97-136.</ref>.
