Perceptual Integrity

Definition

Perceptual Integrity is the condition under which a subject's observation of a given region of the Tower remains consistent with itself across successive viewings. It is the operational baseline against which Perceptual Fade, perceptual lacunae, and Perceptual Contamination are measured, and the standard that Perceptual Safeguarding exists to restore. The term is used loosely in field correspondence and precisely in the Manual of Perceptual Hygiene, which defines it in clause 12 as "the state in which a region, being observed twice, yields one region." The measurement of integrity is expressed as a percentage of concordant readings, maintained by the Office of Perceptual Assurance through its district surveyors. A reading of 100% has never been recorded on any floor above 40. Readings between 94% and 99% are considered unremarkable and are entered in the log without comment.

Contested Status

The prevailing theoretical account, developed at the Academy of Perceptual Absences, holds that Perceptual Integrity is not a property of the observed region but of the relationship between observer and region. On this model, a floor does not "lose" its integrity; rather, the correspondence between successive observations degrades, and the Academy treats this correspondence as the primary object of study. The Academy's model remains the prevailing one, though it has been amended four times since first promulgated. Dissenting accounts are numerous. The school associated with the lower scriptoria argues that integrity belongs to the floor itself and that observers merely report its condition; on this view the Academy's framework mistakes the instrument for the phenomenon. The dispute has never been resolved, and both readings appear in current editions of the Manual without reconciliation, a state of affairs that has been described by the Calibration Schism authorities as "sufficient for working purposes and insufficient for any other."

Decline and Thresholds

Integrity decline is catalogued under Perceptual Ell Measure and reported against fixed thresholds. A region falling below 88% is placed under Type-C containment protocols pending survey. Below 76%, the region is entered as a Perceptual Paradox and closed to unscripped traffic. Below 50%, the region is recorded once, sealed, and not re-entered; three such seals have been broken in the last century, each against written advice. The relationship between integrity and dilation remains disputed. Dilation events frequently precede integrity loss by 40 to 60 hours, but a substantial minority of logged dilations resolve with no measurable decline. The Academy treats the correlation as indicative; the dissenting school treats it as incidental and points to the floor-11 case of the winter of 91, where integrity held at 97% through eleven consecutive dilation entries before collapsing to 61% in a single afternoon.

Regulatory Instruments

Integrity maintenance falls under the Manual of Perceptual Hygiene, which is administered by the Office of Perceptual Assurance. Subjects working in affected zones are issued Perceptual Scrip, which carries a stated integrity floor; exceeding that floor voids the scrip without notice. Scrip-holders are entitled to a replacement on presentation of a voided stub, provided the stub itself retains legible integrity. Regional integrity figures are published quarterly in the annexe to the Concordance and are the only Tower statistics that are formally audited. Audits are conducted by surveyors who do not hold scrip for the region they audit, a separation that has been the subject of at least two Concordance amendments and one long-running grievance by the clerks obliged to enforce it. Where integrity loss coincides with visible physical change — displacement of shelving, alteration of stair geometry, appearance or disappearance of doors — the residue left behind is catalogued as Energetic/Perceptual Residual and separately assessed. Residual readings are not counted toward integrity percentages, a rule that has produced repeated confusion among first-year surveyors and is the subject of a standing note in the field manual reminding them of it.

Notable Readings

The lowest integrity reading ever taken and formally entered is 11%, recorded by Surveyor-Prime Elara Vance on a sealed gallery whose number is omitted from the published annexe. The highest is 99.8%, recorded on floor 4 during a period of no particular distinction. Between these figures lie the entire working literature of the discipline. Integrity is not considered a property that can be repaired in place. Regions are not "restored" to a former reading; they are re-surveyed, and the new reading is entered alongside the old, with both retained. The convention of keeping superseded readings visible in the margin is older than the current Manual and predates the office that administers it.