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Nadine, Is fixation a specific trial type that is different from baseline? If not, then you don't need to model fixation as it becomes the implicit baseline and is the reference for all tasks. I would model correct and incorrect trials for each event type. The reason being is that an incorrect congruent trial is not the same as incorrect incongruent trial. One more cautionary note, for event types that you end up analyzing, you will want at least 30 events in each. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Postdoctoral Research Fellow, GRECC, Bedford VA Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Wed, Jun 15, 2011 at 3:12 PM, Gaab, Nadine < [log in to unmask]> wrote: > Thanks! One follow-up question: If I have 4 conditions (let’s say: > congruent, incongruent, neutral, fixation), do I model 8 (4 conditions x > correct and incorrect) or 5 (four conditions correct plus one with all > incorrect trials)? Thanks, nadine > > > > -- > > "If we knew what it was we were doing, it would not be called research, > would it?" A. Einstein (1879-1955) > > > > Nadine Gaab, PhD > > Assistant Professor of Pediatrics > > Harvard Medical School > > Member of the Faculty of Education > > Harvard Graduate School of Education > > > > Children's Hospital Boston > Department of Medicine > > Division of Developmental Medicine > > Laboratories of Cognitive Neuroscience > Office 611 > 1 Autumn Street, Mailbox # 713 > Boston, MA 02115 > > [log in to unmask] > > phone: (857)-218-3021 > > Main Lab: 617-355-0400 > > fax: 617-730-0518 > > http://www.childrenshospital.org/research/gaab > > or check out: > > http://www.childrenshospital.org/research/gaablab > > > > or take a look at our new study for INFANTS: > > www.babymri.org > > > > *From:* MCLAREN, Donald [mailto:[log in to unmask]] > *Sent:* Wednesday, June 15, 2011 2:21 PM > *To:* Gaab, Nadine > *Cc:* [log in to unmask] > *Subject:* Re: [SPM] regressor versus condition for incorrect responses > > > > Nadine, > > It is recommended that you model the two event separately. You'll have a > correct condition and an incorrect condition. > > The general idea of modelling is to model as much of the variance as > possible in the signal, since you know that you have two types of > conditions, you should model both. > > Best Regards, Donald McLaren > ================= > D.G. McLaren, Ph.D. > Postdoctoral Research Fellow, GRECC, Bedford VA > Research Fellow, Department of Neurology, Massachusetts General Hospital > and > Harvard Medical School > Office: (773) 406-2464 > ===================== > This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED > HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is > intended only for the use of the individual or entity named above. If the > reader of the e-mail is not the intended recipient or the employee or agent > > responsible for delivering it to the intended recipient, you are hereby > notified that you are in possession of confidential and privileged > information. Any unauthorized use, disclosure, copying or the taking of any > > action in reliance on the contents of this information is strictly > prohibited and may be unlawful. If you have received this e-mail > unintentionally, please immediately notify the sender via telephone at > (773) > 406-2464 or email. > > > On Wed, Jun 15, 2011 at 2:15 PM, Gaab, Nadine < > [log in to unmask]> wrote: > > Hi list! We have a quick question. We are analyzing an event-related design > in SPM8 and have correct and incorrect responses. We don’t care about the > incorrect responses and would like to model only the correct responses. Do > people recommend doing this via a regressor (with 0 for incorrect and 1 for > correct responses) or by modeling the incorrect and correct responses as > separate conditions (but ignore the incorrect responses in the contrasts)? > > Thanks > > Nadine > > > > -- > > "If we knew what it was we were doing, it would not be called research, > would it?" A. Einstein (1879-1955) > > > > Nadine Gaab, PhD > > Assistant Professor of Pediatrics > > Harvard Medical School > > Member of the Faculty of Education > > Harvard Graduate School of Education > > > > Children's Hospital Boston > Department of Medicine > > Division of Developmental Medicine > > Laboratories of Cognitive Neuroscience > Office 611 > 1 Autumn Street, Mailbox # 713 > Boston, MA 02115 > > [log in to unmask] > > phone: (857)-218-3021 > > Main Lab: 617-355-0400 > > fax: 617-730-0518 > > http://www.childrenshospital.org/research/gaab > > or check out: > > http://www.childrenshospital.org/research/gaablab > > > > or take a look at our new study for INFANTS: > > www.babymri.org > > > > >