Such “annulation” of effects may explain why DA is less damaging than SA on the long ... on the long-term, especially protective at the psychological level. ...
linkinghub.elsevier.com/retrieve/pii/S0092656607000128
29 Nov 2007 ... a metaphor for psychological annulation. Why is he wearing a wig? sexual ambiguity. Why do we have 2 genders? Why do we have another gender? ...
bloodpixy.this-me.com/.../feedback-from-last-critique-in-graduate-seminar

I think in this context anulación describes a condition, in which the person who uses this defibrillator feels cut out of the reality.

Hope this will help

I could not find any psychology term references to "annulment" in English, but I did find an explanation of the phenomena in Spanish at this link:

http://psicopsi.com/Diccionario-psicologia-letra-A-Anulacion

Específicamente inferido de los actos compulsivos y los ceremoniales obsesivos, en particular los del Hombre de las Ratas, el mecanismo de anulación retroactiva (Ungeschelienmachen) es descrito por Freud en Inhibicion, síntoma y angustia. Supone dos tiempos, el segundo de los cuales consiste en borrar el primero así, por ejemplo, a un acto le sucede otro que lo contradice o tiende a suprimirlo.


The Google translation for anulación is annulment. This is a very different concept from "annulation" from thefreedictionary.com:

an·nu·la·tion (ny-lshn)
n.
1. The act or process of forming rings.
2. A ringlike structure, segment, or part.

There is more to in the link above, but it doesn't sound like denial, withdrawal or undoing either.

One of the defense mechanisms described by Freud is "Anulación", (undoing) meaning the compulsion to reverse acts or feelings which are cause of anxiety by doing the opposite.

It would depend on the whole context, but I'd problably say denial.

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probably :o)

This is the best I can come up with..

Système philosophique, chapitre Conscience
- [ Translate this page ]
L'éveil est le fait pour un sujet de ne pas avoir son activité perceptive diminuée ou annulée (sauf diminution ou annulation de ses capacités perceptives). ...
lucadeparis.free.fr/encyweb/05conscience.htm – Cached

Mind, brain, and the problem of responsibility
by T Szasz - 2000
A hallucinated perception implies a realistic perception from which it devi- ... diminished or annulled, because of mental dis- ease--although that is precisely what the psychia- ... fessional activities--depriving innocent persons of ...
www.springerlink.com/index/BDKLATG2BFV575EL.pdf – Similar

Diccionario de psicologia, letra A, Anulación retroactiva ...
- [ Translate this page ]
Anulación retroactiva (fr. annulatíon rétroactive; ingl. undoing[what has been done]; al. Ungeschehenmachen). Mecanismo de defensa, característico de la ...
psicopsi.com/Diccionario-psicologia-letra-A-Anulacion-retroactiva – Cached

#
Defense Mechanisms
Defense mechanisms are our way of distancing ourselves from a full ... Undoing is the attempt to take back behavior or thoughts that are unacceptable. ...
www.planetpsych.com/...101/defense_mechanisms.htm - Cached - Similar
#
Defense mechanism - New World Encyclopedia
Jump to Undoing‎: The defense mechanism of "undoing" is based on the notion that it is possible to make amends, to correct mistakes made. ...
www.newworldencyclopedia.org/entry/Defense_mechanism - Cached - Similar


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#
It's a Wonderful Life: Mentally Subtracting Positive Events ...
by M Koo - 2008 - Cited by 3 - Related articles
Several studies have examined the affective consequences of mentally undoing negative events, but we are unaware of any that did the same for positive ...
www.ncbi.nlm.nih.gov/pmc/articles/PMC2746912/
# [PDF]
Temporal Uncertainty Time Warp: An Impl

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FEP - Fédération Européenne de Psychanalyse > Glossaire - [ Translate this page ]
Undoing what has been done[en]; tyhjäksitekeminen[fi]; Ungeschehenmachen[de] ... Anulação retroativa[pt]; Anulación retroactiva[es]; 装作未曾发生[zh] ...
www.epf-eu.org/Public/GlossaryList.php?ID=3194&language... - Cached

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Pearson Education - Social Psychology
Social Psychology, Elliot Aronson, Timothy Wilson, Robin Akert. ... Mentally Undoing the Past: Counterfactual Reasoning. Thought Suppression and Ironic ...
www.pearsoned.co.uk › Bookshop - Cached

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http://209.85.229.132/search?q=cache:iSe4bbipc4wJ:www.elpsit...


Entendemos que de esos recursos de la defensa, que no son otros que la anulación y el aislamiento, es posible extraer un hilo conductor que abona el tema que nos ocupa. Así, según Freud, la anulación es una medida precautoria por la que el yo anula el acontecimiento en dos direcciones: se previene para que algo no acontezca o cancela al suceso mismo como si no se hubiese producido, mientras que por medio del aislamiento se "sustrae a una cosa del mundo de todo contacto"establece la pausa que desafectiviza, interrumpiendo tanto los nexos asociativos en el pensamiento, como la detención de la acción hacia los otros.


here's hoping the references are at least useful:)

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http://209.85.229.132/search?q=cache:mlc20uKCxZYJ:www.pptpal...


Freud’s Defense Mechanisms

Freud’s interpretations of how people cope with stresses in their lives
Eleven most common defense mechanisms:
Denial: blocking external events from awareness
Repression: not being able to recall a threatening situation, person, or event
Isolation: involves stripping the emotion from a difficult memory or threatening impulse
Displacement: the redirection of an impulse onto a substitute target
Projection: see your own unacceptable behaviors in other people
Defense Mechanisms (cont.)

Reaction Formation: changing an unacceptable impulse into its opposite
Undoing: gestures or rituals which are meant to cancel out unpleasant thoughts
Introjections/ Identification: copying someone else because you think it is better than yourself
Regression: movement back in psychological time when someone is faced with stress
Rationalization: cognitively distorting the facts to make an event or impulse less threatening to the person
Sublimation: transforming an unacceptable impulse to a productive product