*155OPINION

I. Introduction

Appellant Sarah Jean Clement appeals her conviction for driving while intoxicated. A jury found her guilty of the offense, and the trial court sentenced her to ninety days’ confinement and assessed a $750 fine, suspended imposition of the sentence, and placed Clement on community supervision for eighteen months. In four issues, Clement argues that the trial court erred by compelling her to submit to a field-sobriety test in front of the jury, by overruling her objection to the prosecutor’s “scientific statements” that were made in front of the jury,-by overruling her objection to the arresting officer’s testimony about his physical ailments, and by denying her motion for new trial. For the reasons set forth below, we will affirm the trial court’s judgment.

II. Factual Background

At approximately 1:30 a.m. on September 23, 2011,' a motorist named Michael Cohen was traveling westbound on 1-20 in Fort Worth when he observed a pickup truck driving erratically. Cohen was a member of “Code Blue,” a volunteer citizen’s organization that reports crimé to the police. After following the pickup for a distance and determining that the erratic driving was not an isolated instance, Cohen called 9-1-1. A recording of this call was admitted into evidence and played for the jury. Cohen testified that he followed behind the pickup, reported its location, and recited that the pickup was slowing down to twenty miles per hour and then speeding up to travel fifty miles per hour; had hit. the highway embankment or guardrail, causing sparks to fly; and after exiting the highway, was pulling U-tums on the roadway. After police officers had stopped the pickup, Cohen was directed by dispatch to stop at the scene; he did so, and'he provided officers with his contact information.

Fort Worth Police Officer Dale McCoy testified that on September 23, 2011, at approximately 1:30 a.m., he was on patrol when the dispatcher reported a possible DWI near Officer McCoy’s location. When Officer McCoy arrived at the scene, another Fort Worth police officer had already pulled over the suspected drunk driver for a defective tail lamp. When Officer McCoy approached the pickup, Clement was inside. Cohen was at the scene as well, and the other officer was speaking to Cohen. When Officer McCoy asked Clement to exit the vehicle, her pants were unzipped. Officer McCoy smelled an odor of. alcohol on Clement’s breath. Officer McCoy had Clement perform field-sobriety tests, and the results were that she exhibited six clues on the HGN test, three clues on the walk-and-turn test, and zero clues on the one-leg-stand test. Officer McCoy testified that under the totality of the circumstances he observed at the scene, he determined.that Clement was intoxicated.

A VHS tape recording of Officer McCoy’s roadside administration of the field-sobriety tests on Clement, of Clement’s transport to jail, and of Officer Martinez’s administration of field-sobriety tests on Clement in the Intoxilyzer room at the jail, was admitted into evidence and played for the jury. On the tape,,when Officer McCoy asks Clement, whether she has been drinking, she says that she drank two beers. On the tape of the events in the Intoxilyzer room, Clement agrees to submit a breath specimen, but ultimately no breath specimen was obtained.

At trial, Officer McCoy testified that he had mistakenly checked the box' on his report that indicated Clement had resting nystagmus; persons with resting nystag-*156mus are. not candidates for the HGN test. He agreed that he did not ask Clement the required predicate questions prior to performing the HGN test on her. He also testified that despite Cohen’s report during his 9-1-1 call that the pickup had hit an embankment or a guardrail, there was no damage to Clement’s vehicle and agreed that this was “bizarre.” He also agreed that Officer Martinez, the officer in the Intoxilyzer room with Clement, was not certified to administer field-sobriety tests although he had administered them to Clement. And Officer McCoy agreed that he did not tell Clement that she had the right to a blood test.

Following a particular segment of cross-examination of Officer McCoy, the State asked for permission to “have the witness [Officer McCoy] step down and check for resting nystagmus on this defendant.” Defense counsel objected, stating that “if she [Clement] had resting nystagmus in 2011 [at the time of her arrest], that doesn’t necessarily mean she has it now. That’s over three years ago.” The prosecutor responded, “If she had resting nystagmus three years ago, she absolutely would have it today. It’s not something that just goes away. It’s something that you have or you do not.” Defense counsel then asserted a Fifth-Amendment objection and objected that neither counsel for the prosecution nor Officer McCoy were “qualified to talk about when someone has resting nystag-mus, when it goes away, what causes it, how long it lasts.” The trial court overruled Clement’s objections, Officer McCoy performed an in-court HGN test on Clement, and he commented that “[r]ight now she would have resting nystagmus.11 don’t see any resting nystagmus.”

Officer Martinez testified that Clement had a strong odor of alcohol on her and exhibited four of eight clues on the walk- and-turn test and three of four clues on the one-leg-stand test that he administered to her at the jail in the Intoxilyzer room.2 Officer Martinez said that the “decision point” for intoxication on both tests was exhibiting two clues. Officer Martinez testified that although Clement blew into the Intoxilyzer twice, no breath sample was obtained from her because of her failure to blow with sufficient pressure. Officer Martinez testified that he had no doubt that Clement was intoxicated on the night in question.

III. Issue 1: the In-court Nystagmus Test

In her first issue, Clement argues that the trial court erred by compelling her to submit to an in-court nystag-mus test in violation of her rights under the Fifth Amendment to the United States Constitution and article 1, section 10 of the Texas constitution and that the trial court’s error was compounded by Officer McCoy’s comment about her performance on the test. “The privilege against self-incrimination as contained in both the Fifth Amendment to the United States Constitution and Article I, § 10 of the Texas [constitution protects only testimonial communications.” Adams v. State, 969 S.W.2d 106, 113 (Tex.App.—Dallas 1998, *157no pet.); see also Williams v. State, 116 S.W.3d 788, 791 (Tex.Crim.App. 2003) (explaining that Fifth Amendment applies only to “testimonial communications that are incriminating”). Consequently, requiring a defendant in a criminal case to provide a voice exemplar “does not, without more, compel him to provide a testimonial response.” Williams, 116 S.W.3d at 792. Requiring a DWI defendant to recite the alphabet or count backwards does not violate the Fifth Amendment. See Gassaway v. State, 957 S.W.2d 48, 51 (Tex.Crim.App. 1997). Likewise, a video recording of a DWI suspect performing sobriety tests is not testimonial evidence under the Fifth Amendment. Miffleton v. State, 777 S.W.2d 76, 80 (Tex.Crim.App. 1989). And HGN test results constitute nontestimonial evidence. See Campbell v. State, 325 S.W.3d 223, 233 (Tex.App.—Fort Worth 2010, no pet.). Ac cordingly, because Officer McCoy’s in-court nystagmus testing of Clement did not elicit testimonial communications, the testing did not implicate Clement’s rights under the Fifth Amendment to the United States Constitution or article 1, section 10 of the Texas constitution. See Gassaway, 957 S.W.2d at 51; Miffleton, 777 S.W.2d at 80. And because Clement’s performance during the nystagmus testing was not testimonial in nature, neither was Officer McCoy’s comment regarding her performance. See Youens v. State, 988 S.W.2d 404, 407 (Tex.App.—Houston [1st Dist.] 1999, no pet.) (holding that because appellant’s performance during sobriety tests was not testimonial in nature, trial court did not abuse its discretion by admitting trooper’s testimony concerning manner in which appellant performed sobriety tests); see also Campbell, 325 S.W.3d at 233. We overrule Clement’s first issue.

IV. Issue 2: the Prosecutor’s Statement and the Officer’s Comment

In her second issue, Clement complains that the trial court “erred in overruling defense counsel’s objection to the relevance of improperly admitted scientific testimony!,]” specifically, by overruling her objections to the prosecutor’s statement in front of the jury that “if she [Clement] had resting nystagmus three years ago, she absolutely would have it today. It’s not something that just goes away” and to Officer McCoy’s comment that if Clement had resting nystagmus in 2011, then “[r]ight now she would have resting nystagmus.” Because we are not prepared to hold that the trial court did not err, we address whether such error is harmless.3 See Tex. R. App. P. 44.2(b). Under rule 44.2(b), we review nonconstitu-tional error to determine whether the error affected the substantial rights of Clement. See Tex. R. App. P. 44.2(b). A substantial right is affected when the error had a substantial and injurious effect *158or influence in determining the jury’s verdict. See King v. State, 953 S.W.2d 266, 271 (Tex.Crim.App. 1997) (citing Kotteakos v. United States, 328 U.S. 750, 776, 66 S.Ct. 1239, 1253, 90 L.Ed. 1557 (1946)). Conversely, an error does not affect a substantial right if we have “fair assurance that the error did not influence the jury, or had but a slight effect.” Solomon v. State, 49 S.W.3d 356, 365 (Tex.Crim.App. 2001). In making this determination, we review the record as a whole, including any testimony or physical evidence, the nature of the evidence supporting the verdict, the character of the alleged error and how it might be considered in connection with the other evidence, the jury instructions, the State’s theory and any defensive theories, whether the State emphasized the error, closing arguments, and even voir dire if applicable. See Motilla v. State, 78 S.W.3d 352, 355 (Tex.Crim.App. 2002).

Examining the record as a whole, it reflects that at the close of trial, the trial court admonished the jury orally (when it read the court’s charge to the jury) and in writing (in the court’s charge) to not refer to or discuss anything they had heard about Clement or the case “other than from what you have heard from the witness stand during the trial.” These instructions reduced the likelihood that any error stemming from the prosecutor’s comment influenced the jury. See, e.g., Casanova v. State, 383 S.W.3d 530, 543 (Tex.Crim.App. 2012) (recognizing presumption on appeal that Jurors follow trial court’s instructions). And Officer McCoy’s “[rjight now she would have resting nystagmus” comment, taken in context, was fairly cryptic; the State did not ask for elaboration or further mention the in-court nystagmus test during trial. The State did not mention HGN or resting nystagmus during closing argument, and defense counsel mentioned it only briefly-^pointing out that three years after Officer McCoy stated in his report that Clement had resting nystagmus, he claimed at trial that “it was a mistake.” Defense counsel also mentioned in closing that Officer McCoy had conceded that he had not asked Clement the proper predicate questions before performing the HGN test on her, including whether Clement wore contacts or had head trauma. Thus, defense counsel successfully undermined the reliability of the results of the HGN test performed on Clement on the night of her arrest—regardless of whether the results were also invalid because Clement had resting nys-tagmus. Because admitted evidence undermined the results of the HGN test, performed on Clement on the night of her arrest, the error alleged by Clement concerning the resting nystagmus comments was unlikely to have, significantly - influenced the jury. See Robison v. State, 461 S.W.3d 194, 201-02 (Tex.App.—Houston [14th Dist.] 2015, pet. ref'd) (assuming error in exclusion of evidence and holding it harmless because other evidence that was admitted served the same purpose).

Looking to Clement’s defensive theories, she asserted that she was not intoxicated. She pointed out that she was pulled over because her tail lamp was not working, and she emphasized her perfect performance of the one-leg-stand test and her good performance on the walk-and-turn test as reflected in the State’s video of the roadside field-sobriety tests. In light of Clement’s other stronger defensive theories— i.e., that she was not intoxicated—the alleged error impacting Clement’s defensive theory that she had resting nystagmus on the evening of her arrest likely had but a slight effect on the jury. Accord Villarreal v. State, 453 S.W.3d 429, 440-41 (Tex.Crim.App. 2015) (holding, in charge-error harm analysis, that erroneous omission of defensive instruction was not egregious *159when instruction went to only alternative defense raised by defendant).

And considering the character of the alleged error and the nature of the evidence supporting the verdict, we note that eyewitness testimony from Cohen supports the jury’s verdict. The audio recording of Cohen’s 9-1-1 call was played for the jury, and Cohen testified in person at trial, providing the jury with the opportunity to gauge his credibility. See Garcia v. State, 367 S.W.3d 683, 687 (Tex.Crim.App. 2012) (recognizing that jury, as factfinder, is sole judge of witnesses’ credibility and weight to be given to witnesses’ testimony); Hooper v. State, 214 S.W.3d 9, 13 (Tex.Crim.App. 2007) (recognizing appellate court must defer to jury’s resolution of conflicts in testimony, weight of evidence, and inferences drawn from evidence).4 Given the eyewitness testimony, which, if believed by the jury, established Clement’s erratic driving for an extended period of time— including failing to maintain her lane, slowing down and speeding up, hitting an embankment or guardrail, and making multiple U-turns at 1:30 a.m.—and Clement’s own videotaped statement that she had consumed two beers, the character of the alleged error juxtaposed with the evidence of guilt that the jury could have believed provides us with assurance that the alleged error did not influence the jury or had but a slight effect. See Motilla, 78 S.W.3d at 366 (explaining strong evidence of guilt may provide assurance that error had but slight effect). Because, after reviewing the entire record, we have fair assurance that the alleged error did not influence the jury or had but a slight effect, we overrule Clement’s second issue. See Tex. R. App. P. 44.2(b); Solomon, 49 S.W.3d at 365.

V. Issue 3: Officer Mccoy’s Physical Ailments Testimony

In her third issue, Clement asserts that the trial court abused its discretion by permitting Officer McCoy to testify about his own physical ailments over her relevancy objection.- On cross-examination, defense counsel elicited testimony from Officer McCoy that performance on the field-sobriety tests could be impacted by a performer’s physical ailments and established that Officer McCoy had not asked Clement whether she suffered from any physical limitations. On redirect of Officer McCoy, the State pointed out that Officer McCoy had physically demonstrated for Clement how she was to perform the field-sobriety tests and then questioned Officer McCoy about his own physical ailments. Officer McCoy testified that he had lupus, a herniated disc, and sciatica.

Evidence that is otherwise inadmissible may become admissible when a party opens the door to such evidence. Williams v. State, 301 S.W.3d 675, 687 (Tex.Crim.App. 2009), cert. denied, 560 U.S. 966, 130 S.Ct. 3411, 177 L.Ed.2d 326 (2010). A party opens the door by leaving a false impression with the jury that invites the other side to respond. Hayden v. State, 296 S.W.3d 549, 554 (Tex.Crim.App. 2009); Daggett v. State, 187 S.W.3d 444, 452 (Tex.Crim.App. 2005).

Defense counsel’s questioning of Officer McCoy left the jury with the impression that, due to the degree of physical agility and coordination required to perform the field-sobriety tests, anyone with a physical ailment or injury would not be able to properly perform the tests. Because of this false impression created concerning the physicality required to properly perform *160the field-sobriety tests, we hold that the trial court did not abuse its discretion by overruling Clement’s relevancy objection to Officer McCoy’s testimony about his own physical limitations. The State cleared up the false impression by eliciting Officer McCoy’s testimony regarding his physical ailments, which did not hinder his performance of abbreviated versions of the field-sobriety tests and his performance was captured on video at the scene. See Williams, 301 S.W.3d at 687 (assuming evidence of extraneous murders was inadmissible under rule 404(b), and holding no abuse of discretion because appellant opened the door by deliberately choosing to question prosecutor about them); Jordy v. State, 413 S.W.3d 227, 231-32 (Tex.App.—Fort Worth 2013, no pet.) (holding trial court did not abuse its discretion by allowing State to clear up false impression regarding the correlation between the HGN and alcohol concentration). We overrule Clement’s third issue.

VI. Issue 4: Denial of Motion for New Trial

In her fourth issue, Clement argues that the trial court abused its discretion by denying her motion for new trial following a hearing because her right to a fair trial was substantially affected by the admission of the in-court nystagmus test and by Officer McCoy’s comment regarding her performance on that test. We analyzed these arguments above and held that neither the in-court nystagmus test nor the results of that test were testimonial in nature, that they did not implicate Clement’s privilege against self-incrimination, and that the trial court did not abuse its discretion by permitting the in-court test over Clement’s Fifth Amendment objection. Concerning Officer McCoy’s comment that Clement would have resting nystag-mus “[r]ight now” if she had it in 2011, we held that any error stemming from the comment was harmless. Thus, Clement’s right to a fair trial was not substantially affected by the admission of the nontesti-monial in-court resting nystagmus test, by comments concerning Clement’s performance on that test, or by Officer McCoy’s comment concerning resting nystagmus. See Gassaway, 957 S.W.2d at 51. Accordingly, we hold that the trial court did not abuse its discretion by denying Clement’s motion for new trial. See Tex. R. App. P. 21.3 (setting forth nonexhaustive list of grounds that require granting a new trial); Colyer v. State, 428 S.W.3d 117, 122 (Tex.Crim.App. 2014) (stating that abuse-of-discretion standard is used for denial of a motion for new trial); Wyatt v. State, 23 S.W.3d 18, 30 (Tex.Crim.App. 2000) (rejecting appellant’s argument that cumulative effect of errors at trial denied him right to a fair trial when the court had previously rejected each of appellant’s individual arguments); see also Wright v. State, 178 S.W.3d 905, 929 (Tex.App.—Houston [14th Dist.] 2005, pet. ref'd) (holding that trial court did not abuse its discretion by denying hearing on motion for hearing and new trial regarding whether in-court demonstration was based on speculation). We overrule Clement’s fourth issue.

VII. Conclusion

Having overruled each of Clement’s four issues, we affirm the trial court’s judgment.

DAUPHINOT , J., filed a dissenting opinion.

dissenting

At first blush I agreed with the knowledgeable majority regarding the degree to which the improper statements of Officer McCoy and the prosecutor harmed Appellant. But after closely examining the vid*161eos and record, the conclusion seems, to me, inescapable that the weaknesses of other elements of the State’s case substantially increase the impact of the improper statements. The State’s own case impeached much of its evidence and rendered much of its other evidence suspect. After many hours of closely examining the record, I can only conclude that the visiting trial judge reversibly erred by abandoning her gatekeeping role and allowing the prosecutor and Officer McCoy to make scientific statements in front of the jury over Appellant’s objection regarding the presence or absence of resting nystagmus in her eyes at the time of the offense and at trial, with no evidence of their competence or the competence of their theories, and that the trial court reversibly erred by denying Appellant’s related motion for new trial. The harm from these errors was exacerbated by the magistrate’s denial of a continuance Appellant sought to address untimely disclosed Brady1 information and the visiting trial judge’s denying Appellant any opportunity to proffer expert testimony to contradict the surprise pseudo-scientific expert statements of the prosecutor and Officer McCoy to the jury. Because my colleagues do not agree with me about the extent of the error or join me in concluding that the error is harmful, I must respectfully dissent.

Summary of Facts

Fort Worth police officer Dale McCoy did not make the stop but arrived soon after Appellant was pulled over, and he testified at trial. Officer McCoy stated that Appellant smelled of alcohol and that he decided to conduct field sobriety tests. He testified that Appellant passed the one-leg stand test but failed the HGN test and the walk-and-tum test; she was then arrested for DWI. On direct examination, Officer McCoy testified that Appellant’s walk was “swayed, staggered, and unsteady.” But on cross-examination, he agreed that Appellant had had no - problems with balance when getting out of the car or during the HGN test. Officer McCoy acknowledged that before performing the HGN test, he did not ask Appellant whether she had had any recent head injuries. He also acknowledged that at the police station after her arrest, Appellant stated that she had recently had some head injuries. He further testified that although he checked the box for “yes” on his offense report'in answering whether Appellant had resting nystag-mus, that was a mistake, and he meant to put “no.”

The video of Appellant performing the field sobriety tests shows no unsteadiness, no swaying, and no staggering. Indeed, she performed the tests well. It was impossible, however, to see how she performed on the HGN test because any jerking in the eye is quite subtle and difficult to see, especially when not standing near a person being tested. The only evidence of nystag-mus is Officer McCoy’s testimony.

He further testified that, although his team had a portable breath test device (PDT) to test for the presence of alcohol in a suspect at the scene of the stop, he chose not to use it. Nor did he seek a warrant for a blood test but instead relied on the observations of Cohen. Officer McCoy testified that when he arrived, another officer on the scene told him that Appellant’s pants had been completely off when he first saw her. Officer McCoy testified that Appellant’s pants were on but unzipped.

In the State’s redirect examination at trial, the prosecutor asked Officer McCoy to step down and check Appellant for resting nystagmus. Appellant’s attorney objected, “I’m not tendering [Appellant] as a witness, Your Honor,” and pointed out that *162“if she had resting nystagmus in 2011, that doesn’t necessarily mean she has it now.” The prosecutor responded, “If she had resting nystagmus three years ago, she absolutely would have it today. It’s not something that just goes away.” The prosecutor further argued that “this is non-testimonial in nature, and he’s able to, for demonstrative purposes, check if she has resting nystagmus.” Appellant’s attorney countered that neither the prosecutor nor the police officer was “qualified” to “talk ajoout when someone has resting nystag-mus, when it goes away, what causes it, [or] how long it lasts,” The trial court overruled the objections and allowed Officer McCoy to check Appellant for resting nystagmus. Officer McCoy then testified that “[r]ight now she would have resting nystagmus. I don’t see any resting nystag-mus.”

Appellant later moved for a mistrial on the basis of this in-trial resting nystagmus test and argued that performing the test in open court was a violation of her right to remain silent and to not present evidence against herself. She also requested that she be granted a continuance if the mistrial were denied so that she could get her own- expert “and come baek and revisit this” issue. The trial court denied the motion for mistrial as well as the request for a-continuance.

I agree with the majority that the purported resting nystagmus testing was not testimonial. The Texas Court of Criminal Appeals has held that Article I, Section 10 of the Texas Constitution is somehow limited to the scope of the Fifth Amendment to the Constitution of the United States, despite the clearly distinct language of the Texas Constitution guaranteeing that a person accused of a criminal offense may not be compelled to provide evidence against himself or herself.2 Further, this court has held that HGN evidence is non-testimonial in a suppression case.3

Error

Respectfully, this court’s determination that being compelled to perform an in-court nystagmus test does not .violate the Fifth Amendment because it is not testimonial does not vest the testifying officer with expertise either to perform the test or to interpret the results without the State’s laying sufficient predicate to show the officer’s expertise so that the .trial court may perform its gatekeeping mandate, nor does it authorize the attorney eliciting the officer’s testimony to offer scientific opinion before the jury as an expert. The record does not reflect that either the prosecutor or Officer McCoy had been designated as an expert regarding resting nystagmus.41 therefore disagree with the majority that the officer’s testimony regarding the results of the in-trial resting nystagmus test was admissible. Nor do I understand the reluctance of the conscientious majority to provide necessary guidance to the bench and bar by explaining why all the statements were inadmissible rather than merely assuming error, and that in part.

In her second issue, Appellant argues that the trial court reversibly erred by overruling her objection to the prosecutor’s “making scientific statements in front of the jury” and by “overruling defense counsel’s objection to the relevance of im*163properly admitted scientific testimony.” Within this issue, she specifically complains about .the admission of Officer McCoy’s resting, nystagmus testimony, “Right now she would have resting nystag-mus. I don’t see any resting nystagmus.”

As our sister court in Houston has explained,

Application of the Kelly factors is germane to evaluating whether an expert’s opinion will withstand 'scrutiny outside of the courtroom.-Expert testimony that is not grounded in methods and procedures acknowledged by scientists in the particular field of study amount to no more than subjective belief or unsupported speculation. Unreliable ¡evidence is of no assistance to the trier of fact and is therefore inadmissible under Texas Rule of Evidence 702.

The proponent of expert testimony based on á scientific theory must show by clear and convincing evidence that it is: (1) reliable; and (2) relevant to assist the trier of fact in its fact-finding duty. Consequently, the State, as the proponent of the evidence, had the burden of producing evidence of the. underlying scientific theory behind the expert testimony. ... For VGN [vertical gaze nys-tagmus] and resting nystagmus evidence to be admissible, the proponent must present evidence of similar research of the scientific theory underlying those tests. ... Without scientific proof behind this theory, we cannot find the evidence admissible.5

Thus, the proponent of scientific evidence bears the burden of proving reliability by satisfying the criteria set forth in Kelly.6 The trial court must conduct a hearing to determine whether the proponent has established those criteria.7 Neither the prosecutor nor Officer McCoy was qualified as an expert in testing and evaluation of resting nystagmus. Nor was the scientific theory they propounded proved under the Kelly standard.8

Officer McCoy’s testimony that he had mistakenly indicated in his report that Appellant had resting nystagmus is significant because, according to him, a person with resting nystagmus cannot be tested accurately for HGN. Indeed, Officer McCoy testified that had Appellant had resting nystagmus at the time of the DWI arrest, he would not have performed the field sobriety tests. Yet, he testified that he did perform the HGN test before the DWI arrest and that Appellant failed the test, showing signs of HGN that indicated intoxication.

In her objection, Appellant also challenged the relevance of the in-court test, .stating that whether she showed signs of resting nystagmus at trial was no indication of whether she had shown resting nystagmus three years before when she was arrested. The trial court overruled the objection. Officer McCoy checked Appellant for resting nystagmus and spontaneously testified, apparently in response to the attorneys’ discussion, “Right now she would have resting nystagmus. I don’t see any resting nystagmus.”

Even if we assume that requiring Appellant to submit to a resting nystagmus field sobriety test in front of the jury was not in *164itself error, the record does not reflect that the jury was in any position to see the subtle movements of Appellant’s eyes or the absence of such movement. The trial court allowed Officer McCoy to tell the jury what Appellant’s physiological response allegedly was and further allowed him to explain to the jury the meaning of the response. It is well established that “[f]or testimony concerning a defendant’s performance on the HGN test to be admissible, it must be shown that the witness testifying is qualified as an expert on the HGN test.”9 The same is true for a witness testifying about a defendant’s performance on a resting nystagmus test.10

The State made no effort to lay the necessary Kelly predicate either for Officer McCoy’s testimony regarding the transience or' permanence of resting nystag-mus or for the prosecutor’s opinion. The visiting trial judge abused her discretion by abandoning her gatekeeping obligations and admitting the purported scientific evidence sponsored by the State with no showing of its validity or reliability, in contravention of Kelly.11 Likewise, the trial court abused its discretion by denying Appellant’s motion for new trial based on the admission of the same purported scientific evidence.

Harm

After Officer McCoy’s examination ended and the visiting trial judge called a short recess, Appellant requested a hearing outside the presence of the jury, where she agaiu complained about the test:

I objected to my client being tendered at the request of counsel for the prosecution to have the test for resting nys-tagmus performed on her in open court. [The] Court of Criminal Appeals has said in Emerson that it is, in fact, a scientific test. This is how this officer can even talk about it in the first place. It has to be done correctly. ... Additionally, since it is a scientific test— Well, I would ask for a mistrial based on those grounds.

Secondly, since it is a scientific test, if the Court denies a mistrial, then I would like a continuance to get my own expert and come back and revisit this. I don’t think it’s—for rebuttal testimony.

Counsel for the prosecution said something that, well, once there’s resting nystagmus, there’s always resting nystagmus. She said that in the presence of the jury. Well, that’s just not true. I mean, if you have a concussion, you’re gonna have resting nystagmus. Three years later, if you don’t still have a concussion, you may not still have resting nystagmus. I would ask that the Court .grant the mistrial on those grounds or give me time to get my expert to rebut. .

After the State responded, Appellant continued,

Judge, my argument is that because of Emerson, it is a scientifically valid test, and it can come in through the officer. My argument is that I want my own expert to testify. I wanna know if he did the test for resting nystagmus correctly. I wanna have it videotaped, if I need to, and then submit it to my expert, or at least have time to present an expert for rebuttal testimony.

After the State again responded, Appellant noted that “there [was] no way [she] could have known that the officer was going to say that the resting nystagmus he put in his own report was a mistake until *165he took the stand and testified as such.” The trial court denied both Appellant’s motion for mistrial and her motion for continuance for time to secure an expert to meet and rebut the surprise nystagmus testimony and statements.12

The ability to present expert testimony has long been considered an important element of presenting a defense in a criminal case, but it has also been recognized as an important element of assisting the jury to interpret and judge the validity of the prosecution’s evidence. As the Supreme Court of the United States has explained in considering whether there is an obligation to provide an indigent defendant with funds to pay an expert when the defendant’s mental condition at the time of the offense is at issue,

The private interest in the accuracy of a criminal proceeding that places an individual’s life or liberty at risk is almost uniquely compelling. Indeed, the host of safeguards fashioned by this Court over the years to diminish the risk of erroneous conviction stands as a testament to that concern. The interest of the individual in the outcome of the State’s effort to overcome the presumption of innocence is obvious and weighs heavily in our analysis.

We consider, next, the interest of the State. ... The State’s interest in prevailing at trial—unlike that of a private litigant—is necessarily tempered by its interest in the fair and accurate adjudication of criminal cases. Thus, also unlike a private litigant, a State may not legitimately assert an interest in maintenance of a strategic advantage over the defense, if the result of that advantage is to cast a pall on the accuracy of the verdict obtained. We therefore conclude that the governmental interest in denying Ake the assistance of a psychiatrist is not substantial, in light of the compelling interest of both the State and the individual in accurate dispositions.

Last, we inquire into the probable value of the psychiatric assistance sought, and the risk of error in the proceeding if such assistance is not offered. ... [I]n subsection (e) of the Criminal Justice Act, Congress has provided that indigent defendants shall receive the assistance of all experts “necessary for an adequate defense.” Numerous state statutes guarantee reimbursement for expert services under a like standard.13

The right to assistance of an expert is not exclusive to the indigent defendant; even a defendant in a criminal case who has not claimed indigent status, like Appellant, is entitled to expert assistance in an appropriate case.14

The State argues that Appellant invited the prosecutor’s improper scientific conclusion by lodging her objection to Officer McCoy’s testimony. I cannot understand how Appellant’s objection provided the prosecutor with the experience and expertise to qualify as an expert. In addition to erroneously admitting the purported scientific evidence of Officer McCoy and allowing the prosecutor’s unsworn testimony regarding the permanence and transience of *166resting nystagmus, the visiting trial judge gave Appellant no opportunity for cross-examination of the prosecutor’s unsworn testimony and no opportunity to secure the assistance of a defense expert to meet and rebut either that unsworn testimony or Officer McCoy’s purported scientific evidence.

Further, the evidence at trial conflicted on the issue of intoxication, as shown by this chart:

[[Image here]]

*167[[Image here]]

*168[[Image here]]

Appellant filed a pretrial request for a witness list and a list of experts the State intended to rely on. After trial but before Appellant filed her motion for new trial, Officer Bolling was indicted for manslaughter. In the hearing on her motion for new trial, Appellant argued that because Officer Bolling was the first officer on the scene, she had expected him to testify to explain that he had not completed an accident report because there was no damage to her vehicle. Evidence of the absence of damage from the person who actually examined the vehicle at the scene could have impacted not only the intoxication evidence but also the evidence of the justification for the stop—the alleged defective taillight. Defense counsel stated to the judge in the hearing on the motion for new trial,

Well, since he’s been indicted for manslaughter, I highly doubt that they [the State] would sponsor him now. But I would have subpoenaed him not to discuss his potential criminal case but to testify about the fact that he didn’t complete an accident report because there was no damage to the vehicle.

Like this court, the Overton court was also presented with scientific evidence15 and Brady issues16 that substantially impacted the issue of guilt. As Judge Cochran explained in her concurring opinion, defense counsel may be constitutionally ineffective for not permitting the jury to hear expert testimony contradicting the State’s experts’ theories of criminal liability “and [to] make its own assessment of credibility and scientific reliability.”17 Further, as the Texas Court of Criminal Appeals has noted in the double jeopardy/mistrial context,

*169If the jury’s guilty verdict is significantly influenced by a prosecutor asking legally improper and prejudicial questions, offering inadmissible evidence, or making improper remarks to the jury, that verdict will be reversed on appeal regardless of whether the prosecutor intentionally or recklessly struck a foul blow. As one court put it, “it hurts the defendant just as much to have prejudicial blasts come from the trumpet of the angel Gabriel.”18

Under the specific facts of this case, I believe we are compelled to hold that the trial court’s error in admitting Officer McCoy’s testimony was harmful and therefore requires reversal under rule 44.2(b).19 Because the erroneous admission of Officer McCoy’s testimony about the permanence and transience of resting nystagmus was harmful, I believe we should likewise sustain Appellant’s fourth issue, which complains of the denial of her motion for new trial.

Conclusion

Because the majority does not sustain Appellant’s second or fourth issue, reverse the trial court’s judgment, and remand this case for a new trial, I must respectfully dissent.